Download HCC Anthropology Lecture Chapter 1

PHYSICAL ANTHROPOLOGY 2301 (SECTIONS 4-6)
TEST 2 MATERIALS
BIOLOGICAL ANTHROPOLOGY AND EVOLUTION? (SECTION 1)—What is?
(Biology and Culture, Variation, Evolution, Adaptation, subfields), Science and
Evolution (Characteristics, theory, evidence for, science and religion (almost 2
chapters in length)
HUMAN GENETICS (SECTION 2)—molecular genetics, Mendelian genetics,
Mutations
EVOLUTIONARY FORCES (SECTION 3)—Population genetics, evolutionary forces
THE ORIGIN AND EVOLUTION OF SPECIES (SECTION 4)—the birth and death
of species, misconceptions about evolution, a brief history of life
THE STUDY OF HUMAN VARIATION (SECTION 5)—measuring human variation,
the racial approach to variation, the evolutionary approach to variation
HUMAN ADAPTATION (SECTION 6)—types of adaptation, climate and human
adaptation, high-altitude adaptation, nutritional adaptation
THE HUMAN SPECIES (SECTION 7)—characteristics of living humans, the human
life cycle, is human behavior unique?
THE BIOLOGY AND BEHAVIOR OF LIVING PRIMATES (SECTION 8)—a
discussion on the biology of primates
HOMINID ORIGINS (SECTION 9)—the first hominids, evolutionary trend
THE EVOLUTION OF GENUS HOMO (SECTION 10)—the origin of genus homo,
homo erectus, archaic humans
THE ORIGIN OF MODERN HUMANS (SECTION 11)—anatomically modern homo
sapiens, recent biological and cultural evolution of homo sapiens
HUMAN BIOLOGY AND CULTURE CHANGE (SECTION 12)—The biological impact
of agriculture, the biological impact of civilization, recent changes
PHYSICAL ANTHROPOLOGY 2301 Lecture
THE ORIGIN AND EVOLUTION OF SPECIES--Section 4
I.
The birth and death of species
A) This section deals with macroevolution or large scale evolutionary changes
especially speciation that require hundreds of generations (H. Curtis
glossary)
B) Macroevolutionary changes are usually only detected in the fossil record
(paleontologically)
1. Speciation refers to the process by which new species are produced
from earlier ones
2. Species refers to a group of organisms that can interbreed to produce
fertile offspring
3. Essentially, members of one species are reproductively isolated from
all other species
4. There are certain issues that render Relethford’s general definition of a
species problematic
a) This definition is only extremely useful when animals are examined
b) Some bacteria and protists (example amoeba) do not breed at all
as far as is known
c) Also some plants can have fertile crossings between many different
kinds of plants
5. Relethford places emphasis on the biological species concept with a 3
fold definition
a) organisms from different populations must be capable of
interbreeding
b) these matings must occur in nature (no laboratory hybrids)
c) the offspring must be fertile or capable of producing offspring
themselves
6. Curtis notes that a profound change in the concept of species occurred
with the development of evolutionary thought
7. Initially, a species was thought of as being an immutable ideal form
8. This changed to a species being seen as changing constantly in both
time and space
9. Relethford notes that the idea of a species may be too rigid and that
because constant change is taking place there are groups (he uses
gypsy moths in Asia) that are the same “species” that produce sterile
offspring
10. Marks sees the reason that species differ from one another as due to 2
ideas
a) their gene pools are different
b) their gene pools cannot become more similar to one another by
interbreeding (gene flow)
c) What is important about these 2 dual processes is that the are dual
processes
d) Therefore, there is no way to predict for certain that because the
gene pools (or phenotypes) are different by a certain amount that
the 2 populations are consequently unable to breed
e) According to Marks the ability to interbreed is not closely related to
the acquisition of genetic or anatomical divergence
f) This makes the division of species particularly difficult when
analyzing fossil material
11. One of the key ideas behind the development of speciation is the idea
of reproductive isolation
a) This idea is based on genetic change that leads to an inability to
produce fertile offspring or an elimination of gene flow between
populations
b) An important isolating mechanism is geographical isolation where a
geographical barrier such as a mountain range or ocean effectively
separates populations
c) Relethford notes that there are other possible ways of speciation
(different habitats—eating at different times), but that at least one
person sees little evidence of speciation without geographic
isolation
12. Genetic divergence
a) Relethford notes that isolation does not always lead to speciation
and that other forces are needed
b) However, Turnbaugh etc. claim that as long as gene exchange is
limited populations can only become more genetically different
over time (due to genetic drift and subsequent changes in allele
frequencies)
c) Genetic divergence can occur due to natural selection, mutation
and genetic drift
d) The view of the process of divergence has changed from the idea of
natural selection operating on large populations to mutation and
genetic drift in small populations
13. It should be noted that usually speciation results in 2 new species,
however, many new species can develop in a short period of time in a
process known as adaptive radiation
a) These radiations often occur when a group of animals colonizes a
new geographical area that offers numerous open econiches (Jolly
and Plog)
1) Often radiations occur when there are no other species to
compete in a given area (marsupials in Australia)
2) Occasionally major adaptive radiations occur when a particular
animal stock previously insignificant in fauna evolves to open
up previously unusable habitats
a. An example of this involves members of the superorder
Crossopterygii during a time period of 375 to 350 million
years ago
b. This group modified the swim bladder (an organ that gives
buoyancy in swimming) into a lung
c. They thus developed the ability to take oxygen directly from
the atmosphere
d. At the same time their fins changed into stumpy, but
muscular lobes that enabled them to move (in limited
fashion) outside the aquatic environment
e. These unique abilities allowed them to survive seasons
when water in their pools became deoxygenated, stagnant
or even dried up altogether
f. Much of speciation is a gamble that can often lead to
extinction, but this fishes ability to breathe air is a
preadaptation
g. A preadaptation is defined by Jolly and Plog as a
characteristic that is acquired as an adaptation to a
specialized or narrow eco-niche, but which turns out to be
advantageous in a new set of circumstances
h. This preadaptation is seen as the basis for all successive
adaptive radiations of land vertebrates (lungs and limbs are
inherited)
b) Independent adaptive radiations tend to produce evolutionary lines
that adopt the same general mode of life
c) The adaptations are, however, superimposed on different basic
body plans
d) When dissimilar unrelated lineages evolve superficially similar
forms in this way it is known as convergence (Jolly and Plog)
e) An example of this idea is the icthyosaur, a type of sea creature
who lived 200 million years ago that resembled a fish, but was
actually a reptile
f) Mammalian radiation produced a similar group (whales and
dolphins) that also look like fish, but are not
g) A related phenomenon is called parallelism
1) parallelism is a phenomenon that occurs when related species
of similar general adaptation independently take up similar
ways of life
2) These species come to resemble each other in special
adaptations more than either resembles the ancestral form
3) Parallelism is often difficult to detect and can be misleading
4) For example seals, sea lions and walruses on the surface would
appear to be derived from land based carnivores (dogs, bears,
cars etc.)
5) However, Seals on the one hand and sea lions and walruses on
the other are derived from at least 2 separate parallel sea
invasions by land based carnivores
6) The sea/lion walrus group is closer to dogs and bears, true
seals are phylectically closer to weasels
7) Ideas such as the existence of flippers can tell us little about
common ancestry
h) The resemblances that are due to parallelism and convergence are
known as analogies
i) This idea is placed in opposition to homologies which are
resemblances retained from a common ancestor
C) The tempo and mode of macroevolution or gradualism versus
punctuationalism
1. The traditional view of evolution has emphasized that change
accumulates gradually in evolving lineages or the idea of phylectic
gradualism (Turnbaugh etc.)
a) The term phylectic refers to an idea relating to a phylum or a line
of descent
2. This suggests that if a complete fossil record concerning a group (if it
could be recovered) would show a series of finely graded transitional
differences between each ancestor and descendent
3. This idea dominated evolutionary thought until about the last 20 years
4. Some biologists have questioned this idea because some species
remain the same over thousands of years
5. This thousand years of stasis can be followed by an evolutionary
“spurt” of speciation
6. This uneven, nongradual process of long stasis and quick spurts is
called punctuated equilibrium
7. Evidence exists for both punctuated equilibrium (fossilized marine
invertebrates) and gradualism (Eocene primates).
D) Biological species changes and two modes of evolutionary change in a
species
1. The first mode is based on the idea that a species can change over
time (a single species exists at any given point in time, but evolves
over a period of time
a) This type of change is known as anagenesis or straight line
evolution and involves the transformation of a single species over
time
b) See the illustration on page 99
2. The other mode is cladogenesis or branching evolution
a) Cladogenesis can be defined as the formation of one or more new
species from another over time
b) See the figure on page 100
E) Evolutionary changes can also be distributed in 2 ways
1. they can be distributed across several species or in a single species
a) changes in a single species are known as autapomorphies and
reflect the divergence of that species from its close relatives
(defining its evolutionary individuality)
b) Changes distributed across species are synaptomorphies and
reflect evolutionary modifications in a species (shared derived
characteristics i.e. small teeth) that were inherited by its
descendent taxa
F) Curtis notes that when evolutionary theory became the dominant ordering
principle in the biological sciences, systematics, as the science of
taxonomy is called, took on a new meaning
1. Marks claims that the ultimate source for taxonomic diversity in the
world is speciation
2. The goal is to classify organisms in a way that reflects their
evolutionary history
3. Basically, species are groups that have diverged recently, genera
share more distant ancestors etc.
4. An problem with this system is that all species alive today are equally
modern so there are no ancestors (by definition)
5. Due to this issue degrees of similarity or difference among modern
forms may not represent the closeness of relationship
6. In a traditional sense, taxonomy has depended upon morphological
criteria or the arrangement of parts and the external appearance of
the organism
7. Today, increased knowledge of cellular biochemistry is leading to
greater reliance on biochemical criteria
a) This includes the composition of the cell membrane (outermost
membrane of a cell) and the cell wall or the use of certain anabolic
or catabolic pathways
b) A cell wall is a rigid structure produced by the cell and located
outside the cell membrane in most plants, algae, fungi and bacteria
(in plant cells it is usually composed of cellulose)
c) Anabolism refers to the total chemical reactions in a cell involved in
synthesis (the synthesis of the thousands of molecules within a cell
are made within the cell)
d) Catabolism refers to the process of breaking down larger molecules
8. Some groups such as bacteria are difficult to place within a taxonomy
because their forms are variable and their evolutionary histories are
largely unknown
G) Taxonomy
1. Scientists even before Linnaeus (1707-1778) recognized the largest
category of a Kingdom
a) Early ideas were based on whether an item was in the plant,
animal or mineral kingdoms
b) However, Linnaeus and other taxonomists have added further
categories
c) Starting with the largest grouping or Kingdom the groups in
decreasing size are: phyla, classes, orders, families, genera and
species
d) There are also subgroupings in each category
e) It should be noted that there are also several different
classification systems in use with 2, 3 or 5 Kingdoms
H) Extinction
1. Extinction is seen by Marks as the opposite of speciation and involving
the elimination of taxa from the world
2. Futuyama claims that over 99% of all species that ever existed have
become extinct
3. However, Ehrlich and Ehrlich argue that the occasional extinction of
less successful organisms are balanced naturally by the founding of
new populations (transformations apparently not counted as
extinctions)
a) They note that during most of that time more species were being
created than were going extinct creating the biodiversity present
today
4. Marks sees 2 kinds of extinctions
a) Background extinctions are those events that mark the end of a
species attempts to compete successfully and to thrive (a failure on
the part of an entire species)
b) mass extinctions are results of major ecological catastrophes
resulting in the extinction of many different species during a brief
geological time span (not a failure due to competition, but to
chance)
c) The result of a mass extinction is an evolutionary vacuum that
results in a “free-for all” where the surviving species expand
d) The free for all that resulted after a meteor struck the earth (or
other variations on this theme is the reason that mammals
supplanted the dinosaurs about 65 million years ago
e) Ehrlich and Ehrlich suggest that these mass extinctions have
occurred periodically and that the last such event was the
aforementioned one 65 million years ago
f) However, they suggest that another global epidemic of extinctions
is taking place on a similar scale
g) This is not due to cataclysmic forces, but to the actions of human
beings
h) It is difficult to estimate the amount of species lost
i) However, biologists think that losses of bird and mammal species
in the last few centuries has been 5 to 50 times the normal rate
j)
Toward the end of this century the rate of extinction has risen to
40 to 400 times the normal rate
I) Other ideas on evolution and 2 types of analysis (phenetic and cladistic)
1. The outcome of the evolutionary processes of speciation, radiation and
extinction is a large array of species some extant and others extinct
and known only through their fossil remains
2. Evolutionary theory suggests that all of these species are ultimately
related to each other
3. Each species can, therefore, be considered as the tip of a branch of an
imaginary phylectic (phylum or line of descent) tree, whose forks
represent speciation and subsequent divergence
4. In theory only one phylectic tree can represent whet happened in
evolutionary history
5. Comparisons between species are used in the construction of these
trees
6. Structures such as limbs, teeth and even protein molecules and
elements of social behavior can be used as a basis for such
comparisons
7. If enough characteristics are measured than a reasonable estimate of
overall resemblance of phenetic (a classification system based on the
similarity of characteristics) distance can be achieved
8. This phenetic form of analysis is one of the two major types of analysis
for the phylectic tree (the other is cladistic)
9. If for example, species A resembles species B in 20 characters, but
species C in only 5 then species A is phenetically closer to B than C
10. Phenetic distance is usually a good indicator of phylectic distance
11. However, not all resemblances are of equal weight when determining
phylectic relationships
12. Some of the resemblances are from a an ancient common ancestor
and do not reflect a recent common ancestor
a) An example is a comparison between the human hand and the
opossum paw which are somewhat similar in appearance is due to
the retention of an ancestral condition (also seen in many
reptiles)—no phylectic significance
b) However, zebras like horses have only one functional finger and is
a derived condition (from the hand) that indicates that they have a
relatively recent common ancestor
13. The major drawback to this system is that a large part of evolution
consists of divergence and a divergent group may be dissimilar to
other related groups
14. Thus a species that has changed a lot in a short time may look
unrelated
15. The science of genetics has helped with classification because changes
in genetics are much slower than changes in anatomy
16. Cladistic, the second major type of analysis concerning the phylectic
tree focuses on the evolutionary process (Marks)
17. It focuses not so much on the accumulation of distance between
species, which can be abstractly quantified, but rather as the historical
succession of particular traits through time
18. An example is the development of canine teeth where humans have
small teeth while monkeys and old world apes have large canines
19. It is assumed that humans evolved from those that had large canines
20. The reasoning behind this is the idea that an earlier something in a
primitive or plesiomorphic state changes to a “something else” in an
apomorphic or derived state
21. Marks notes that because it is easier not to evolve than to evolve
apomorphys are rare
22. A key problem with cladistic analysis is the determination of polarity or
the idea of whether large canines evolve into small canines or viceversa
23. Small canines are seen as derived so the original large teeth,
therefore, the groups with large canines does not tell us which species
are closely related
24. This idea of a shared primitive feature is known as symplesiomorphic
and only offers a number of different lineages where the event of
interest did not occur
J) Misconceptions about evolution
1. Bigger is better—the reality is that there needs to be a balance
between the adaptive and non-adaptive aspects of any biological
organism (smaller may be better in some situations
2. Newer is better—age has no bearing on usefulness
3. Natural selection always works—environments can change too quickly
for it to work
4. There is an inevitable direction to evolution (orthogenesis)—evolution
is random
5. Natural selection always produces perfect structures—movement from
fur-legged form to two legged in humans led to problems such as
hernias
6. All structures are adaptive—many structures are a by-product of other
biological changes
7. Current structures always reflect initial adaptations—structures are
frequently modified for different uses
K) A brief history of life
1. read handout
HCC Physical Anthropology (2301) Lecture
The STUDY OF HUMAN VARIATION--Section 5
I.
Measuring human variation
A) A key idea to remember is that race is a descriptive concept and not an
analytic tool
B) Relethford suggests the term race is a often misleading label for variation
and explains nothing
C) Historically there are several approaches to the idea of race
1) racial classification, is an approach that has been rejected
a) Johnston and Selby suggest that the first reaction to human
biological variability was to deny humanity to other groups
b) These polygenists (multiple species) held that the different groups
encountered were different species
c) Gradually, a monogenist view of race developed, specifically, that
we are all one species
d) Since 1735 and until the middle of the 20 th century taxonomies
have appeared regularly concerning the idea of race
e) Before World War II most studies of human variation focused on
phenotypic variation between large, geographically defined
populations and the studies were largely descriptive
f) However, after that time, the emphasis has shifted to the
examination of allele frequencies within and between populations
g) The adaptive significance of both phenotypic and genotypic
variation also became the method of examination
h) According to Kottak (127) phenotype reflects an organism’s evident
traits or its manifest biology—anatomy and physiology
i) The shift in focus from race to genotype and phenotype in the post
World War II era arose due to the development of the “Modern
Synthesis” in the field of biology
1. Evolution in terms of the “modern synthesis” is a 2 stage
process
a. the production and redistribution of variation (inherited
differences between individuals)
b. Natural selection (genetic differences lead to higher
reproductive success for some individuals)
j) During the 1950s the idea of a “race” changed to the idea of an
“ethnicity” due to the word “race” falling into disfavor
k) Strictly speaking ethnicity refers to cultural factors so some have
objected to its inclusion in discussions that also include biological
characteristics
D) Biological Determinism is defined as the concept that phenomena,
including various aspects of behavior (intelligence, values, morals, etc.)
are governed by biological (genetic) factors
1) It represents the inaccurate association of various behavioral
attributes with certain biological traits such as skin color (Turnbaugh
etc.)
2) Essentially, the idea is that cultural variations are inherited in the
same manner as biological variations
3) The main idea is that some groups are by nature superior to others
4) For example, in the middle of the 19 th century it was common practice
to rank people based on skin color (as well as the size and shape of
the head) with Africans at the bottom
E) Explaining skin color or the adaptive significance of human variation
1. Kottak (112) sees skin color as rooted in the ideas of Charles Darwin
and Alfred Russell Wallace, specifically, natural selection
a) Natural selection refers to the process by which nature selects the
forms most fit to survive and reproduce in a given environment
(less fit organisms die out)
b) Richard Leakey’s discussion on Darwin’s Origin of species notes
that since the 1930s and 1940s the operation of natural selection
has been widely recognized as the driving force of evolutionary
change and research has tended to confirm this
c) However, Leakey also admits that there are biologists who are
unhappy with this idea and criticize the “everything is adaptive”
approach in what he admits is a valid argument
d) He further notes that if one is looking for an adaptive explanation it
is all too easy to find one
2. Kottak (113) claims that skin color is a complex biological trait and is
influenced by several genes
3. Melanin is the primary determinant of skin color and the melanin cells
of darker skinned people produce more and larger granules of melanin
than do those of lighter skinned people
a) Melanin can be defined as (127) a substance manufactured in
specialized cells in the lower layers of the epidermis (outer skin
layer); melanin cells in dark skin produce more melanin than do
those in light skin
b) Kottak (113) notes that by screening out ultraviolet radiation from
the sun, melanin offers protection against a variety of maladies,
including sunburn and skin cancer
4. Kottak believes natural selection or resistance levels to ultra violet
radiation explains the geographic distribution of skin color
a) The darkest populations in Africa evolved in the sunny open
grasslands
b) Once one leaves the tropics located between the tropics of Cancer
and Capricorn (north or south) skin color gets lighter
c) In the tropics those with the darker skin color are more protected
from UV radiation (sunburn increases potential for disease and
impairs the body’s ability to sweat and UV radiation can cause skin
cancer)
d) Another issue relating to geographic distribution of skin color is
vitamin D production by the body
e) In northern Europe where clothing is important for protection from
the cold vitamin D production (from UV radiation) is reduced
potentially diminishing the absorption of Calcium by the intestines
A. This led to rickets (a softening of the bones)
f) The protection against this is light skin color which maximizes the
absorption of UV radiation
g) In the tropics the dark skin color protects against excessive
absorption of UV radiation since too much radiation can lead to
hypervitaminosis where calcium deposits build up in the body’s soft
tissues (potentially fatal)
F) The eugenics movement is a movement encouraging the production of
healthy children
1) The eugenics movement originated in late-19th century Europe (Marks)
and was an outgrowth of Darwinism
2) It flourished in America between 1910 and 1930 and died out with
World War II
3) It is out of the eugenics movement that the study of human genetic
variation was born
4) The ability to breed animals for desired traits was extended the
breeding of humans for desired traits
5) It should be noted here that not all eugenicists favored destroying the
incompetent (mentally ill etc), but that the focus was on producing
“better” children
6) Racist eugenicists, however, wanted whole ethnic groups sterilized or
otherwise ostracized on account of their undesirability
7) This initial focus on the population (all individuals) was contested by
Harvard professor Earnest Hooten who suggested that all races had
favorable and unfavorable qualities
8) This is, of course still a racist idea, but it is not quite as racist as
exterminating whole groups of people
9) The key issue concerning Hooten is that he drew attention to
polymorphism or the biological variation that exists within species
G) Race and definitions
1) Kottak (107) claims that biologically race would be a geographically
isolated subdivision of a species.
2) Kornblum (415) sees it similarly when he claims that race is an
inbreeding population that develops distinctive physical characteristics
that are hereditary.
a) such a subspecies would be capable of interbreeding with other
subspecies of the same species
b) However, geographic isolation would eventually lead to the
development of a new species
H) Parrillo (23) notes that racial classification is merely a sociopolitical
construct, not a biological absolute
1) Parrillo says that in the past “race” has been used to as a general
term to include both racial and ethnic groups giving it both a biological
and social meaning
2) Recently, ethnic group has been used to include the 3 elements of
race religion and national origin
I) The idea of Social race
1) Kottak (116) notes that the races that we hear about every day are
culturally constructed and have little to do with biological differences
2) Wagley (Kottak 116) claims that they are biological races or groups
assumed to have a biological basis but actually defined in a culturally
arbitrary rather than scientific manner
3) In the U.S. racial identity is established at birth
a) Kottak (116) gives the example that the child of a “white” parent
and a “black” parent is automatically labeled as black when
genetically it would be just as logical to label them white
b) He also says that anyone known to have a black ancestor in some
states is considered to be black
c) This idea of identity established at birth has not always held true
1 Quan (1982) claims the Chinese in early Mississippi were
initially considered to be “black” and intermarried into that
population in small numbers
2
J)
K)
L)
M)
N)
However, the arrival of increasing numbers of Chinese women
and establishment of a normal family life led the Chinese to be
moved into their own racial category
3 Quan notes that the movement to this new category in the post
1920s period brought them a higher status that placed them
between black and white groupings in the Mississippi mindset of
the period
4 One of my professors at L.S.U. suggested that historically I
would have been black because my skin is darker than a sheet
of paper suggesting that ideas of ethnicity/race change
d) The notion of automatic “blackness” despite having one white and
one black parent is a rule of descent or an assigning of social
identity on the basis of ancestry
e) Kottak and Harris argue that the U.S. notion could be called
hypodescent because it places children of mixed ancestry in the
minority category
f) Hypodescent helps divide American society into groups that have
been unequal in their access to wealth power and prestige
Turnbaugh and others claim that all contemporary humans are members
of the same polytypic species, homo sapiens
1) a polytypic species is one composed of local populations that differ in
regards to the expression of one or more traits
2) Most species can be seen as polytypic, therefore, there is no species
type to which all members exactly conform
Kottak (108) says that there are gradual shifts in gene frequencies
between neighboring populations (no sharp breaks) are called clines
Relethford agrees with this idea when he suggests that skin color is an a
continuum (clines)
a) C. Loring Brace (Heider 57) claims that early explorers who
traveled on land from Herodotus (5th century B. C. E.) to Marco
Polo (14th century) were aware of human physical variation but
were not tempted to think in terms of racial categories because
they had experienced the variations bit by bit in all of the clines
b) However, with the advent of ship voyages in the 15th century which
ended in the discovery of the New World the idea of “races” began
to emerge (due to a skipping of the intermediate populations)
In addition to the aforementioned notion of clines other anthropologists
have criticized the idea of race because it implies that traits are clustered
together
1) This idea of a clustering of traits is known as concordance
a) An example would be a distribution of hair color from dark to light
in an east-west direction
b) However, stature is distributed from tall to short in a north south
direction
c) Hair color and stature are not concordant and are discordant
d) If one adds other traits and gene frequencies then there is little
concordance for any single race
2) Another criticism of the idea of race has arisen from the from the
investigation of the distribution of variation
a) Simply put there is greater variation within a race than between
races
Further problems with racial labels
II.
a) the labels do not accurately describe skin color (white and Hispanic
can vary)
b) The three initial groupings (Caucasoid, Negroid and Mongoloid) did
not cover all groups, therefore, additional races had to be added
c) Another problem is that phenotypical characteristics on which races
are based supposedly reflects genetic material that is shared and
has stayed the same for long periods of time, but phenotypes
might or might not have to have a genetic basis
d) An example of a non-genetic issue is the initially short statured
population of Japan
e) This lack of height was based on diet and as Japanese begin to eat
less traditional foods the average height has begun to increase
Biochemical variation
A) One of the most common genetic measures used in studies of human
variation is human blood type
1) Different blood group systems are identified by the types of molecules
present on the surface of red blood cells
2) Each system has a certain antibody-antigen reaction that can be used
to identify different blood groups
3) Relethford claims that antibodies are agents that react to foreign
substances or antigens that invade the blood stream
4) Johnston and Selby see antigens as substances that identify each of us
and that if an antigen that is not already present enters the body then
the body manufactures antibodies to fight it
5) The antibody-antigen reaction or clumping of red blood cells allows for
the classification of different blood groups
6) Johnston and Selby claim that there are more than 20 blood groups
known to exist in humans and that 10-15 of these vary from
population to population (are polymorphic)
7) Each blood group is controlled by a different locus and in some cases
the inheritance is simple and well understood
a) An example of this is the ABO blood system
b) In this blood system there are 3 alleles (A,B,O) where A and B are
codominant and O is recessive
c) There are also 4 phenotypes Type A (AA, AO), type B (BB, BO),
Type O (OO) and type AB (AB)
d) Two antibodies react to specific antigens with anti-A reacts to A
type molecules (blood type A or AB) and anti-B reacts to B type
molecules and(blood type B or AB)
e) Each blood type has a different combination of A and B antigens
the reactions allow us to establish blood type (see Table 5.1 on pg.
121)
f) Relethford’s example is that people with type A blood have the A
antigen, but not the B
g) If a sample of blood is taken and the blood clumps when exposed
to anti-A antibodies and not to anti-B then the person has Type A
blood
h) This transparency presents the frequency of alleles for the for the
blood groups of a number of populations
1. where a value is not given we have no information on that
system
2. There is a pattern
a. The O allele of the ABO system is universally present in
American Indians of the South American rain forest
b. The presence of A or B indicates a history of European or
African admixture
c. Among Native Americans the frequency of O ranges
between .7 (70%) and 1.0 (100%), but can be lower in the
southeastern and northwestern U.S.
d. O is quite common among American Indians, but its
frequency is lower in Asia
e. Similar patterns emerge for other blood groups
8) However, Johnston and Selby ultimately argue that other blood typing
systems are complex and not completely understood
B) DNA
1) Relethford suggests that many new methods of biochemical variation
focus on the direct examination of DNA
2) One of the methods for examining DNA focuses on restriction
fragment length polymorphisms
a) This can be defined in terms of the length of DNA fragments
produced when certain enzymes cut the DNA sequence
b) These enzymes are produced by different types of bacteria and are
known as restriction enzymes
c) These enzymes bind to sections of DNA and cut the DNA sequence
at a certain point
d) A difference in a person’s DNA sequence will change the location
where it is cut, therefore changing the length of the DNA fragment
e) The key issue is that changes in the length of DNA sequences is a
measure of human variation
C) Complex traits
1) these traits are frequently affected by growth and environment and
reflect a more complicated relationship between genotype and
phenotype than biochemical variation
2) The measurement of the human body, skull and face is known as
anthropometrics
a) The two most common measurements in this arena are height and
weight
b) There are also measurements of the skull such as length, width
and height
c) In 1842 Anders Retzius, a Swedish anatomist developed the
cephalic index as a method of describing the shape of the head
d) The cephalic index was derived by dividing maximum head breadth
by maximum length and multiplying by 100 to give a ratio of head
breadth to length (it does not measure head size, but is a ratio)
e) Today, this index is seen as simplistic, but in the 19th century it
was highly significant
f) With this method it was easy to categorize people because a single
number was derived and it was an efficient method for describing
variation
g) Northern Europeans were characterized as dolichocephalic or as
having a long narrow head in which the width measures 75 percent
of the length
h) Southern Europeans were characterized as brachycephalic or as
having a broad head in which the width measures more than 80%
of the length
i)
III.
It is not surprising to note that this issue of head size led to heated
and nationalistic debate over whether one group was superior to
the other or not
3) Skin color (discussed earlier) is also a complex trait
a) Relethford notes that in the past skin color was often measured by
comparing a person’s skin to a standardized set of tiles
b) This was seen as inaccurate so today a reflectance
spectrophotometer or a device that measures the percentage of
light reflected back from a given source at different wavelengths
c) This machine offers precise measurements of skin color, however,
the meaning of the measurement for some populations is
questionable
d) For example, skin color can vary by individual over time due to
tanning or “paling”
1. When I was younger my skin was much darker than it is today,
because I was outside more often
2. Freckles can also be added to this category with variable skin
color depending on if one has measured a freckle or not
e) skin color can also change with disease
1. The disease vitiligo (in slang the Michael Jackson disease)or
leukoderma causes the skin to appear milk-white in color
2. The variation in skin color in terms of the disease would make
measurement by a reflectance spectrometer variable on a
single individual (as with freckles)
The Evolutionary approach to variation
A) This approach uses evolutionary forces such as mutation, natural
selection, gene flow and genetic drift
1) Since some factors are singular and others multiple depending on the
evolutionary force it is important to make a distinction between the
two
2) Univariate analysis refers to examining one trait at a time and can be
used to examine gene flow and genetic drift (they affect all loci to the
same degree—an expectation not a fact)
3) Multivariate analysis or examining many traits at one time and is used
to evaluate natural selection
a) Natural selection should affect each locus differently and,
therefore, it is measured one trait at a time unless related traits
are being examined
4) it should be noted that a study should consider all evolutionary forces
at one time (univariate and multivariate used together)
B) Gene flow and Genetic Drift and methods of analysis
1) Relethford notes that when comparing a number of biological traits
across populations scientists often compute a measure known as
genetic distance
2) Johnston and Selby claim that Genetic distance between populations is
large if the frequencies of the alleles of the 2 gene pools are markedly
different
3) If the differences are small than genetic distance is small
4) Relethford sees genetic distance as a measure of relatedness between
populations based on a number of traits
5) When 2 groups are measured the analysis is fairly straightforward
6) However, when more groups are examined a genetic distance map is
developed
7) A genetic distance map is a picture showing the genetic relationships
between populations based on genetic distance measures
8) A real world example of genetic distance can be seen among the
Yanomamo Indians and neighboring populations in the Amazon jungle
a) The key issue here is the isolation of the Yanomamo and
subsequent genetic drift among them and other groups in the
Amazon jungle
b) Even individual villages show genetic and morphological (from body
measurements) differences
c) So essentially when groups are small and isolated from each other
morphology can drift as much as alleles
9) the effects of genetic drift and gene flow can also can also be derived
from demographic measures such as population size and migration
10) In the absence of genetic traits this sort of analysis allows for an idea
of the relative magnitude of genetic change likely in certain conditions
C) Natural selection
1) Any analysis of natural selection in human populations is complex, but
can be seen in terms of 3 methods
a) The most direct method involves comparing measures of survival
and reproduction among individuals with different genotypes
b) A second method involves is to examine regional or worldwide
variation in a trait to determine if it has any relationship with
climate or other environmental factors
c) The last method is to look at the potential for natural selection by
using measures of births and deaths in demographic data
PHYSICAL ANTHROPOLOGY 2301Lecture
HUMAN ADAPTATION—Section 6
I.
Human Adaptation or the successful interaction of a population with its
environment
A) Some definitions of adaptation and related ideas
1) Marks sees adaptation as a particularly difficult concept in evolution
because it means 2 things, arises in several ways and is not easy to
identify when present
a) Marks’ 2 meanings of adaptation are
1. a feature providing a benefit over its alternatives to an
individual in a particular environmental circumstance
2. the process by which such features arise
2) adaptation or the process of adapting can be seen as relating to 4
different processes
a) adaptation occurs by natural selection, as a consistent bias in the
survival and reproduction of individuals with particular genetic
configurations (a genetic process)
1. morphological differences among individuals are produced
b) adaptation occurs as the result of physiological or behavioral
plasticity via a long or short term environmental stress on a
relatively undifferentiated organism (a developmental process)
1. morphological differences between groups or among individuals
within a group are produced
c) adaptation occurs as the result of choices made by individuals in a
direct response to a particular situation (behavioral, but the actors
choice is one that directly enhances their welfare)
1. behavioral variation within or between groups are produced
d) a particularly human mode of adaptation in which a corporate
decision is made that may sacrifice short-term benefits to
individuals in the interests of long term benefits to the collective (a
behavioral adaptation based on based on foresight)
1. behavioral differences among human groups are produced
3) Identifying particular features as adaptations
a) this implies a great deal of knowledge, specifically the use of the
feature, the origin of the feature and the manner by which it arose
b) This sort of knowledge is often incomplete, therefore one should be
tentative in assuming that specific features are adaptations
c) Problems arise because a particular biological structure has several
uses and it is, therefore, often unclear as to which use was “the”
adaptive function for which the structure evolved
4) Relethford sees the idea of stress as central to the study of adaptation
(one of Marks processes)
a) stress is defined as any factor that interferes with the normal limits
of operation of an organism
b) organisms maintain these limits through an ability known as
homeostasis
1. homeostasis physiologically refers to the maintenance of
normal limits of body functioning
B) In terms of adaptation, the fit between how an animal appears, what it
does, and where it lives and explaining that fit has been a major focus of
the study of life for centuries (Marks)
1) The most enduring explanation for these questions is the one holding
that each species has no history, having existed from the beginning in
the same form
a) This means that it has been doing what it does, looking as it does
and living where it lives in an unchanging scenario
b) The last influential version of this idea was the “watchmaker”
analogy of William Paley
1. His theory suggests that the intricate match of an organisms
parts to one another, to its lifeways, and to its surroundings is
likened to the construction of a precision timepiece
2. Paley reasoned that watches are designed and precision-crafted
by a maker
3. Species are crafted in a similar way and designed to fit
perfectly into their space in nature
C) Darwin in his Origin of Species suggested an alternative that modern
science has found more fruitful…the idea that each species has a history
1) The fit of an organism to its environment, therefore, must be the
result of a long process of adapting
2) This occurs because all members of a species do not survive or
reproduce with equal efficiency
3) The consistent ability of organisms with certain given attributes to
perpetuate themselves more efficiently than other members of the
same species lacking those attributes results in the transformation of a
species through time
a) This is certainly the origin of the various breeds of dogs (and
pigeons) that have been bred into existence during human history
4) It is the environment Darwin reasoned that determines which
characteristics permit an organism to survive and reproduce
disproportionately in nature
5) For example changes in animal breeds are wrought by human
intervention where certain traits are consciously chosen for the next
generation
a) An illustration of this is the development of the Basset hound
1. Prior to the French Revolution of 1789 hunting was the sport of
noblemen and the long legged hound was preferred (Urban)
2. After 1789, the hunter was more apt to be the common man
who accompanied his dogs on foot
3. The need was for a dog that was strong enough and shortlegged enough to conquer dense underbrush
4. Also a dog was needed that had skin that was loose enough to
slip and slide over the terrain rather than impaling the dog on
the brush
5. Lastly a short legged dog was needed that could easily keep its
nose to the ground and ultimately the scent
a. In terms of the basset hound long ears were seen as
important because they were believed to channel the scent
to the bassets highly developed olfactory system
b. However, this is not actually the complete story because the
early Basset hounds were different then the modern Basset
A. The modern Basset was created in England and is a cross
of the French breeds (most influential was the Basset
d’Artois) and the beagle and bloodhound
6) In an analogy to human selective breeding the natural world decides
which traits continue albeit passively and unconsciously
7) The net result of both human and natural world selective breeding is
the same
8) Specifically that descendent populations develop that diverge
anatomically from their ancestors and other descendent populations
D) Types of Adaptation
1) There are 3 basic types of adaptation, specifically, genetic, cultural and
physiologic
2) It should be noted that physiological responses to environmental
change is to some degree influenced by genetic factors
3) Physiologic adaptation can be divided into four forms
a) Acclimation that refers to short term changes that occur very
quickly after exposure to a stress
1. Relethford offers an example of sweating when one is hot
b) acclimatization that refers to physiologic changes that take longer
(days to months)
1. an example is red cell production after moving to a high
altitude climate
2. Turnbaugh and others believe that short term (anytime in a
single lifetime) physiological responses to environmental
change are called acclimatization
c) When change occurs during the physical growth of an organism it
is known as developmental acclimatization
1. An example is the increase in chest size that occurs when a
person grows up at high altitudes
d) There are also long term adaptations that can be seen in terms of
physiological changes
1. an example of this is deeply pigmented skin in tropical regions
e) it should be noted that the ability of organisms to respond
physiologically or developmentally to environmental stresses is
called plasticity
E) Climate and human adaptation
1) Mammals and birds have evolved complex mechanisms to maintain a
constant internal body temperature allowing for increases or
decreases of loss in body heat (Turnbaugh etc.)
2) However, reptiles must rely on exposure to external heat sources to
raise body temperature and energy levels
3) The optimum body temperature for normal cellular functioning varies
by species and is 98.6 in humans
4) Homo Sapiens is found in a wide variety of climate types ranging from
extremely hot (over 120 degrees F) to bitter cold (less than –60
degrees F)
5) In these extremes (particularly the cold) human life would not be
possible without cultural innovations (environmentally friendly clothes,
housing etc.)
6) However, even when accounting for the artificial environments in
which we live the human body in the extremes is under enormous
stress
F) Heat and cold stress
1) Relethford claims that in terms of heat stress there are 4 ways in
which heat is lost from the body
a) radiation is heat flow from objects in the form of electromagnetic
radiation
1. The body can remove heat, but also get heat from heat
radiated by other objects
b) Convection refers to the gradual removal or gain of heat through
air molecules
1. heat flows from a warm object to a cooler one
c) conduction is heat exchange through physical contact with the
ground or clothes
1. only a small percentage of heat exchange
d) evaporation is the loss of heat through the conversion of water to
vapor
1. it results in heat loss without heat gain
2) The best available evidence suggests that the earliest hominids
evolved in the warm to hot savannas of East Africa
3) The fact that humans deal better with heat than they do with cold
suggests a long term adaptation that evolved in our ancestors
4) In humans and some other animals (horses) sweat glands are
distributed throughout the skin
a) this wide distribution of sweat glands makes possible the loss of
heat at the body surface through evaporative cooling (evolved to
the greatest degree in humans)
b) The sweat gland distribution in human populations is fairly constant
c) However, there is variation in persons not generally exposed to hot
climates where the initial acclimatization process involves increased
perspiration rates
d) An additional factor that enhances the cooling effects of sweating is
increased exposure of the skin through reduced amounts of body
hair
5) Another method for radiating body heat is vasodilation where
capillaries near the skin’s surface widen to permit increased blood flow
to the skin
6) This leads to flushing or increased redness of the skin accompanied by
warmth
7) The physiological effect is to permit heat carried by the blood from the
interior of the body to be emitted from the skins surface into the
surrounding air
8) Body size and proportions are also important in regulating body
temperature
9) There seems to be a general relationship between climate and body
size and shape in mammals and birds
a) Generally, within a species body size or weight increases as the
distance from the equator increases
b) In humans this relationship holds up fairly well, but there are
numerous exceptions
10) 2 rules that pertain to the relationship between body size, body
proportion and climate are Bergman’s rule and Allen’s rule
a) Bergmann’s rule concerns the relationship of body mass or volume
to surface area
1. In mammals body size is larger in animals that live in colder
climates
2. As mass increases the relative amount of surface area
decreases proportionately
3. Because heat is lost at the surface increased mass leads to
greater heat retention and reduced heat loss
b) Allen’s rule concerns the shape of the body, especially appendages
1. In colder climates, shorter appendages with increased mass to
surface ratios are adaptive because they are more effective at
preventing heat loss
2. Conversely longer appendages with increased surface area
relative to mass are more adaptive in warmer climates because
they promote heat loss
c) according to these 2 rules the most suitable body type in hot
climates is linear with long arms and legs (Swedes exception)
d) The most suitable body type in a cold climate is stocky with shorter
limbs (Italians exception)
11) Human physiological responses to cold combine factors that increase
heat retention with those that enhance heat production
a) heat retention is the more effective of the 2 because it requires
less energy
b) This is important because energy (enhancing heat production) is
derived from dietary sources
c) Because food is not always readily available in winter any factor
that conserves energy can be adaptive
12) responses to cold
a) increased metabolic rate and shivering (generates muscle heat),
both of which generate body heat at least for a short time
1. increased metabolic rate or the rate at which cells break up
nutrients into their components increases with cold and
releases energy
2. increasing metabolic rate and shivering are both costly because
they require an increased amount of caloric intake
b) Vasoconstriction is an involuntary short term response and restricts
heat loss and conserves energy
1. It can be defined as a narrowing of the blood vessels to reduce
blood flow to the skin in an effort to reduce heat loss at the
skin’s surface
2. Vasoconstriction is economical because it retains body heat
rather than creating it
3. It is very efficient providing that temperatures do not drop
below freezing
4. However, if temperatures do go below freezing continued
vasoconstriction can allow the skin temperature to decline to
the point of frostbite or worse
5. A response to this frostbite problem is seen in the Inuit who
have intermittent periods of vasoconstriction and vasodilation
a. This compromise provides periodic warmth to the skin that
helps to ptrvent frostbite in below-freezing temperatures
b. At the same time because vasodilation is intermittent
energy loss is restricted with more heat retained at the
body’s core
c) Additionally humans have a subcutaneous (beneath the skin) fat
layer that provides an insulative layer throughout the body
d) Behavioral modifications for cold can include increased activity,
wearing warmer clothing, increased food consumption and
assuming a curled up position
e) Generally people that are exposed to chronic cold (most of the
year) have higher metabolic rates than those living in warmer
climates
1. for example, the Inuit who live in the Arctic maintain metabolic
rates between 13% and 45% higher than those observed in
non-Inuit control subjects
2. The Inuit traditionally had the highest animal protein and fat
diet of any human population in the world
3. This diet is dictated by the local resource base, served to
maintain the high metabolic rates required by exposure to
chronic cold
G) High altitude
1) Today, as many as 25 million people live at altitudes above 10,000
feet
2) At such high altitudes, multiple factors produce stress on the human
body
a) one of these problems is hypoxia or a reduced amount of available
oxygen in the atmosphere (due to barometric pressure) or to
insufficient amounts of oxygen in the body
1. Hypoxia exerts the greatest amount of stress on human
physiological systems, especially the heart, lungs and brain
2. This condition results from reduced barometric pressure,
therefore, there is not less oxygen at high altitudes it is less
concentrated
3. 2 Effects of hypoxia
a. Reproduction is affected with increased rates of infant
mortality, miscarriage and prematurity
b. Low birth weight is also common and is attributed to
decreased fetal growth due to impaired maternal-fetal
transport of oxygen
b) More intense solar radiation at high altitudes due to the air being
thinner can be a problem
c) Cold, wind (amplifies cold stress) and low humidity can be issues
d) Also a reduced nutritional base and rough terrain can contribute to
problems found at high altitudes
e) Populations at high altitudes show slowed growth, and maturation
levels and an enlarged chest associated with greater lung volume
and larger hearts
3) Frisancho claims that compared to high altitude natives, nonnatives
exhibit some differences in acclimatization to hypoxia
4) Frisancho terms these different responses “adult acclimatization” and
“developmental acclimatization”
a) Adult acclimatization occurs upon exposure to high altitude in
people born at a low elevation
1. The responses may be short term modifications, but they begin
within hours of the altitude change
2. These changes include an increase in respiration rate, heart
rate and production of red blood cells
a. red blood cells contain hemoglobin, the protein responsible
for transporting oxygen to organs and tissues
b) Developmental acclimatization occurs in high-altitude natives
whose adaptations are acquired during growth and development
i.e. they are born at high altitudes
1. These individuals have a higher lung capacity and are more
efficient than migrants at diffusing oxygen from blood to body
tissues
2. Therefore, they do not rely as heavily on increased red blood
cell formation as do newcomers
H) Nutritional adaptation
1) Nutrition has an effect on human growth at every stage of the life
cycle
a) During pregnancy, for example, a woman’s diet can have a
profound effect on the development of her fetus and the eventual
health of the child
b) The effects from this are transgenerational because a woman’s own
supply of eggs is developed while she herself is in utero
c) Thus if a woman is malnourished during pregnancy the eggs that
develop in the female fetus may be damaged in a way that will
impact the health of her future grandchildren
2) Nutrients that are needed for growth, development and body
maintenance are organized into 5 major categories
a) proteins that are composed of amino acids are the major structural
components in muscles, skin, hair and many organs
b) carbohydrates are important sources of energy needed to run the
body and are significant because they are converted to glucose,
the only source of energy used by the brain
c) Lipids include fats and oils and serve in the capacity (once
processed by the body) of stored energy
d) Vitamins serve as components of enzymes that speed up chemical
reactions
1. There are 2 types of vitamins
a. water soluble (B and C vitamins)
b. fat soluble (not water) such as vitamins A,D, E, and K)
2. fat soluble vitamins can be stored so deficiencies in them are
slow to develop
e) minerals needed by the body are not organic compounds and
include calcium, , phosphorus, potassium, sulfur, sodium, chlorine
and magnesium
1. Other minerals are Iron, iodine, zinc, manganese, copper,
cobalt, fluoride, molybdenum, selenium and chromium
3) Evolution of nutritional needs
a) our nutritional needs have co-evolved with the types of food that
were available to our human ancestors throughout our evolutionary
history
b) because the earliest mammals and the first primates were probably
insect eaters, humans have inherited the ability to digest and
process animal protein
c) Early primates also evolved the ability to process most vegetable
material and some incorporated fruits into their diet
d) Consequently fruits and vegetables are important dietary items for
modern humans just as they were for our early primate ancestors
e) Human needs for vitamins and minerals reflect ancestral nutritional
adaptations
1. an example of this is our requirement for vitamin C or ascorbic
acid
a. It plays an important role in the metabolism of all foods and
in the production of energy
b. Most animals are able to synthesize it and it is likely that
most primates were able to manufacture their own vitamin
C
c. As monkeys evolved they began to eat more leaves and
fruits and less animal protein, therefore, they received
vitamin C from their food
d. At a certain point these apes lost the ability to synthesize
vitamin C
e. It may have been selectively advantageous to conserve the
energy required to produce vitamin C
f. It would not have been disadvantageous to lose the ability
as long as sources of vitamin C were available
4) Diets of humans before agriculture
a) The preagricultural diet was high in animal protein and low in fats,
particularly saturated fats
b) The early diet was also high in complex carbohydrates (including
fiber), low in salt and high in calcium
c) The modern American diet is high in saturated fats and salt and
low in complex carbohydrates, fiber and calcium
d) Some adaptations such as the ability to store fat were
advantageous in the past when food availability was uncertain
(stored fat for famine), but today obesity is a problem
e) It is clear that both deficiencies and excesses of nutrients can
cause health problems and interfere with growth and development
f) in terms of deficiencies 2 issues can arise
1. Undernutrition or a diet insufficient in quantity (calories) to
support normal health
2. Malnutrition or a diet insufficient in quality (lacking some
essential component) to support normal health
PHYSICAL ANTHROPOLOGY 2301 Lecture THE HUMAN SPECIES—Section 7
I.
Introduction
A) All people wonder what they are, who they are and how they relate to the
other forms of life they see around them
1) There are various answers to these questions offered through different
philosophical and religious perspectives
2) Johnston and Selby suggest that all peoples have “creation myths”
or tales that relate how humans came into existence and offer some
sort of scheme that classifies lifeforms into groups
a) Jo Forty argues that the word “myth” or mythos originally meant
story and was used to differentiate such from factual (logos)
accounts of real events
b) She notes that myths that refer to the remote past have an
important purpose, specifically, to reflect the natural order of
things and to address cosmic origins in some cases
c) These myths can exist in unstratified hunter-gatherer societies and
more complex hierarchical ones
d) My definition of myth is a little less judgmental, specifically, that it
is an explanatory mechanism for events that are usually linked to
religion and possibly creation
e) The key difference is that Forty sees them as fictive, while I do not
see them as fictive or not I merely state that they are explanatory
f) In terms of anthropology this should be an issue because Forty is
suggesting that a cultural idea i.e. religious is wrong or fictive
g) If the ideal of anthropology is cultural relativism should it be
involved in the debunking of peoples beliefs whether they seem
rational or not?
h) Or is anthropology a study of people where their beliefs should be
examined as just that, their beliefs with no value judgments placed
on them
3) Individual peoples differ in the extent to which they regard themselves
as members of the animal kingdom
4) In the Old Testament human beings are viewed as unique a view that
most anthropologists do not agree with (apes have culture etc.
a) The passage in your text (pg. 269) was written between 400 and
100 B.C. and expressed the views of people in a certain culture at
a certain time
b) There is no question that the psalmist saw humans as endowed
with certain privileges
c) This view is still common today not just in the modern world, but
also among people of less technologically developed societies
d) This view has led people in the Western world to waste energy,
exterminate entire animal species and decimate forests
e) This view of humans as the center of the world with everything put
here for our well-being as anthropocentric
5) In contrast to the anthropocentric view there is the view of Ervin
Laszlo who states that:
a) The status of man is not lessened by admitting the amoeba as his
kin….Seeing himself as a connecting link in a complex natural
hierarchy cancels man’s anthropocentrism, but seeing the
hierarchy itself as an expression of self-ordering and self-creating
nature bolsters his self-esteem and encourages his humanism
II.
b) To Laszlo and others who share his ideas we are a part of the
natural world and should realize that this bolsters our self-esteem
and makes us more not less human
6) Neither view is entirely right or wrong since each one expresses the
particular way in which people see themselves as living creatures
a) Scientists have established our place as a part of an interacting
network of living organisms
b) Philosophers, humanists and religious writers have emphasized the
uniqueness of human nature
B) Life: its definitions, characteristics, unity
1) Johnston and Selby suggest that there is no easy definition of life that
will allow us to separate the world into the living and the nonliving
2) They argue that life is said to exist when something displays certain
features and characteristics; we then say its alive
3) These characteristics may be summed up under the 5 headings of
organization, metabolism, growth, sensitivity and reproduction (some
on the fringes of the living and nonliving do not show them all with
equal completeness)
a) organization—the inner contents are not just scattered about
randomly and different structures can be clearly identified
(chemical level atoms, molecules or internal organs)
1. A key idea in terms of organization is that there is a
relationship between structure and function
2. Human hands for example function as they do because the
structure of bones, muscles, nerves, blood vessels etc. permits
and facilitates that function
b) Metabolism—food contains nutrients that the body uses for energy
when performing work (it breaks substances down)
1. Oxygen is taken into an organism for use in chemical reactions
(respiration) and unused substances and by-products are
excreted
c) Growth—new substances are manufactured within the cells,
utilizing the nutrients taken in
1. growth can be seen as the synthesis of other substances
d) Sensitivity—means that organisms react to the environments
surrounding them
1. In simple forms it may involve only chemical change
2. In complex organisms it may involve movement or behavior
3. In terms of humans it means that we interpret our environment
through a mutual interaction with it
e) Reproduction—living cells reproduce themselves and perpetuate
their kind through time
1. reproduction ensures the continuity of life without its having to
be re-created each new generation
Characteristics of living humans and “humans in the past”
A) Distribution and environment
1) Relethford claims that humans are the most widely distributed living
primate species
2) He suggests that humans originally evolved in a tropical climate, but
have since expanded into different environments
3) Humans tend to cluster in areas with benevolent climates and terrain
(National Geographic world atlas)
4) The East coast of the U.S., all of Europe, Japan, coastal China, the
Mexico city area, and the Nile river valley all have high population
densities
5) The arid regions of Africa, Asia and central Australia show low
population densities as do areas of dense rain forest, high
mountainous regions and the Arctic
6) Antarctica has no permanent human residents, however, humans can
live there as they can also live in space and beneath the sea
B) Brain size and structure and its development
1) One of the most obvious characteristics of the human species is their
large brain
2) Human brain size averages about 1300 cubic centimeters because
that size is a good balance between advantages and disadvantages
a) advantages are greater intelligence and general cerebration (the
working of the brain or the process of thought)
b) disadvantages are the high costs due to the need for blood supply
and the reduced mobility of the broadened female pelvis needed
for successful live births
3) During the course of human evolution there has been a general trend
toward increased brain size and complexity (Poirier 139)
4) However, this trend was neither consistent nor steady
a) for example, the size increase was slight during the 3 million years
of early evolutionary history from Australopithecus and early homo
lineages (TRANS. INCREASING BRAIN SIZES-Poirier))
b) However, it became more rapid during the middle Pleistocene in
Homo erectus and later Homo Sapiens
5) Poirier sees increased size and complexity in the brain as being related
to tool use and manufacture, increasing environmental challenges and
more complex social groups
6) Increased brain size and complexity may also be related to an infant’s
slower maturation rate which requires extended parental investment of
time
7) The extension of the period of maternal care allowed for more infant
socialization and placed a premium on learning abilities
8) Learning may also have been enhanced by increasing brain size and
complexity
9) Martin suggests that the upper limit of brain development is
determined while the infant is still in the womb
a) After birth the brain follows a set trajectory:
1. in nonhuman primates typically in primates involves a doubling
of the brain’s weight and in humans the brain weight
quadruples
b) differences in gestation time also have consequences for potential
brain growth
10) Dietary patterns and the resources exploited for food affect brain size
a) for example, among bats fruit eaters have a larger brain size in
relation to their body weight than do insectivores
11) Milton provides an interesting discussion on food acquiring and its
relation to brain size
12) She notes that the extreme diversity of plant foods in tropical forests
and their distribution have been a major selective force in the
development of cerebral complexity in certain higher primates
a) Instead of genetically coding a large variety of dietary information
what develops is behavioral flexibility
b) This allows for continual response to changing forest conditions
c) Milton suggests that increasing mental complexity which places a
strong emphasis on learning and retention may have been selected
for as an adaptation to the environment
d) She also suggests that as the genus homo began to exploit mobile
big game that their lack of claws and powerful jaws caused them to
rely on mental acuity to outwit and capture prey
13) Deacon notes that the evolution of brain/body ratios has most often
involved changes in body size growth rather than brain growth
C) Constraints on brain evolution
1) McKinney suggests that compared with other morphological traits that
shape in the brain is much less closely related to function
a) essentially, the function of the brain for storing and processing
information is largely independent of shape so there are no
selective demands to alter the shape
b) Instead new environmental demands have been met by alterations
in the neural (nerve) networks at fine microscopic scales
c) The extreme functional plasticity of cortical neurons allows them to
be coopted for a variety of different purposes in both development
and evolution
1. For instance, much of our prefrontal (near the forehead) area
(essential for synthesis and planning) has been coopted from
other areas of the primate brain that are no longer used for
other functions
2) Besides shape Brain evolution is conservative in other ways
a) Genetically, there is often surprisingly little difference among
brains of greatly differing morphology (even among distant phyla)
3) In large brains the number of genes required to specify all of the
information coded there would be prohibitively large
a) instead large brains rely on the production of a nervous system
that is strongly influenced by the environment to record and
process information
4) Rates of neuron mitosis in the mammalian fetus are also constrained
a) Neural mitotic rates in all mammal species are similar possibly
representing the maximum rate in the prenatal environment
(human brain growth rate is no different)
b) However, the larger mammalian brains are produced by extending
the period of brain growth
c) Of equal importance humans also slow down the rate of body
growth to produce a high brain/body ratio
d) This difference in relative size due to a disparate growth is known
as allometry
e) Allometry is defined in Relethford as being the study of the change
in proportion of various body parts as a consequence of different
growth rates
f) Deacon estimates that our brains would grow about as fast
(brain/body ratio) if they were in an ape body that would normally
attain an adult body size of 1000 pounds
g) Relethford’s view is that as body size increases the brain size
increases, but not at the same rate (humans seem to be an
exception)
h) The aforementioned idea of slowing body growth to help brain
growth in humans and Figure 10.1 illustrate the point that human
brains are 3 times the expected size if other primates are similarly
measured
5) It should be noted that in addition to the aforementioned processes all
phases of brain development in humans seem to be extended
a) Because the rate of growth is not reduced (as it is with body size)
these delays produce an over developed brain (developmental
prolongation to produce more cells)
6) it should be noted that Relethford goes into a discussion of brain size
and I.Q., but as I have mentioned before, I.Q. tests themselves can be
seen as invalid
D) Bipedalism—moving around on 2 legs
1) Stanford suggests that when we want to find out why the earliest
humans stood up and walked that we turn to other animals
a) an example of the meerkat is offered
b) The meerkats tend to stand on 2 legs as sentinels outside of their
burrows to protect their families
c) Even though meerkats only gain a few inches in height from
standing scientists believe that it gives them an advantage
d) This idea of a bipedal posture for vigilance is one suggestion for
bipedalism in humans
2) However, examples from the animal kingdom including the meerkat
are fraught with peril
3) A key question would be Why an early hominid would need to stand on
2 legs habitually rather than temporarily like the meerkat
4) Stanford suggests that his key argument is to dispense with the idea
that humans evolved from one bipedal ancestor—the “missing link”
5) He offers a new worldview that does not include the idea of progress in
early bipeds
6) Stanford states that we have absolutely no reason to think that
bipedalism arose for one reason only
a) or even to believe that the same factors that drove the origins of
bipedalism later molded it into greater efficiency
7) There seems to be a fixation on apes for the appearance of human
ancestors (chimpanzee) and that without this fixation adding flesh to
Lucy (or other early ancestors) would have been complete guesswork
8) Theories
a) One of the earliest theories espoused by Darwin was the idea that
using tools was fundamental to making us human
b) The evidence is against this theory is that tools appeared 2.5
million years ago and the shift to bipedalism began 3 million years
earlier
c) There are many other theories that have little actual evidence to
support them (speculative)
d) One of the most talked about theories since the 1980s is Lovejoy’s
idea that incorporates food carrying, monogamy and the origins of
the female reproductive system (bipedalism)
e) Lovejoy notes that there has been a decline in the diversity of fossil
apes that started well before the emergence of the hominids (man)
f) He believed that this occurred because of the slow reproductive
rates of great apes (as opposed to the higher rate for monkeys)
g) The breed or die issue came to a head for humans about 5 million
years ago when the drying climate broke up the tropical rainforests
of East Africa (TRANS. Climate 1)
1. This drying up of the landscape forced the hominids to travel
further to obtain food and cross stretches of open country to
find it
h) Lovejoy’s one trait that set off out first ancestors from their simian
cousins was female reproductive physiology
i) He suggests that female protohominids no longer advertised their
ovulation (pink balloons hang from the backs of female
chimpanzees)
j) This is seen as adaptive because of the lack of abundant food made
it necessary for help from the male in gathering food (he needed to
carry it—bipedalism)
k) Many experts disagree with Lovejoy (2003 source)
l) 3 Arguments against Lovejoy
1. it is now believed that the critical stages of human evolution
took place in the forest not in the savannah
2. the sexual swellings in apes is an evolved trait in apes and not
lost in humans
3. Much evidence points to the idea that ancestral hominids had a
polygamous mating system
4. An example of this evidence is that among all monogamous
primates sexual dimorphism is nearly absent, but in humans it
is pronounced
5. It should be noted here that in modern human societies the
majority have a stated preference for polygyny (a form of
polygamy where a husband has several wives
6. And a few cultures in the modern world practice polyandry or a
form of marriage where a wife has several husbands
m) Stanford believes that there is a much more plausible theory for
the origins of bipedalism
1. it needs to be realize that it did not happen for one reason or in
one step
2. He sees the different components of anatomy coming together
at different times for different reasons
3. An essential reason for standing and walking upright must in
his view be intimately tied to eating and reproduction
4. The initial stages of walking upright were tentative, diverse and
suited to modest feeding advantages
5. Only later did longer distance walking become possible, let
alone advantageous
6. And only much later did humans refine their newfound walking
ability for marathoning
7. Walking evolved from quadrupedal apes to diverse protobipeds
with at least one lineage emerging as a long distance biped
8. But at each stage of development no end point was in sight
only an immediate genetic accomodation to a set of
environmental circumstances
9) Stanford sees at least 3 benefits of bipedalism in recent hominids
a) it allows efficient marathon travel in search of game and other
foods
b) it allows agile pursuit of prey
c) it allows people to carry tools, weapons and children
10) How critical is standing upright as a precondition for evolving
sophisticated intelligence
a) We are human in large part by virtue of our technology and
without the ability to stand and walk tool use would not have
reached its high level of development
b) Chimpanzees are seen as the most technologically skilled animals
on earth outside of humans but their posture limits their adeptness
c) Relethford mentions termite fishing where apes use grass stems or
sticks and stick them in termite mounds, twirl it to attract termites
and then pull the stick out and eat the termites
d) He suggests that this requires a great deal of expertise (finding the
right stick) and dexterity (taking the stick out without detaching
the termites)
e) Stanford suggests a problem with this in terms of bipedalism
f) He argues that they have to carry these tools in their lips because
they lack a “free hand”
E) Culture and language
1) The essential question being asked by some of Relethford’s chapter is
what is human and is humaness or portions of humaness unique to
human beings?
2) Relethford looks at the natural world and suggests that chimpanzees
have culture because one community can be readily differentiatedfrom
another by its unique behavioral characteristics
a) again this idea of chimpanzees having culture is dependent upon
the definition being used
3) It is also suggested that chimpanzees can learn ASL (American sign
language) and that language acquisition is no longer a unique human
feature
4) Relethford sums up his idea by suggesting that the differences
between human and ape are not so great as we thought
5) However, this can fall into the same realm of condemnation as Biblical
archaeology
6) The issue with Biblical archaeology is that it is not going to areas to
merely look at what is there, but to seek out something only related to
the Bible
7) Relethford seems to be following the idea of lets see how alike humans
and chimpanzees are instead of also trying to show at the same time
how different they are (ASL is artificially learned by them etc.)
8) Following this same reasoning one could also argue that machines
(artificial intelligence) are approaching humaness through the advent
of “fuzzy logic” and other issues
PRIMATES--Section 8
I.
Primates
A) The word “primate” is from the Latin word "primus" which is first or
possibly foremost--Taronga and Western Plains zoos
http://www.zoo.nsw.gov.au/content/view.asp?id=1038
B) The order of primates includes Prosimians, Monkeys, Apes and
Humans
1) The actual number of species range from a high of 350 to a
low of 190 and O’Neil argues that most estimates are from
230-270 (anthro.palomar.edu)
2) New species are still being found, but it is believed that all the
major primate groupings have been discovered
C) Primates are the most familiar placental mammals (University of
California Museum of Paleontology www.ucmp.berkeley.edu)
1) Placental mammals bear live young
2) They are fed prior to birth in the uterus through an embryonic
organ that is positioned on the uterine wall known as the
placenta.
3) The placenta is produced from the protective membrane or
amnion that is filled with amnionic fluid surrounding the
embryo in birds, reptiles and monotremes.
4)
The idea of "placental mammals" is somewhat misleading
because marsupials also utilize a placenta.
5) The placenta in the marsupials is short-lived, also it does not
make nearly as much contribution to fetal feeding as it does
for eutherians, also known as "placental mammals" in a
scientific sense.
D) Primates are diverse in their weights, which can vary from a few
ounces to around 400 pounds (O’Neil)
E) All primates except spider monkeys (and deformities) are pentadactyl
or have five fingers on their hands and five toes on their feet
1) some of the digits on all primates have nails and not rigid
claws allowing for the manipulation of objects (and food)
2) Prehensile or grasping hands can vary due to the opposability
of the thumb
3) All of the primates except humans also have prehensile feet
4) Different species have different abilities in terms of grips
a) The smaller new World monkeys use all of their fingers
together to gain purchase on tree limbs
b) Some of the apes and monkeys have greater dexterity
and can use a power grip by flexing the fingers and
palm against the opposing force of the thumb
c) Some apes (and humans) utilize precision grips
through opposing fingers to the thumb allowing for a
manipulation of tiny objects
F) Further Characteristics of primates
1) Primates also have pads on the ends of their digits that are
sensitive and that are strengthened and protected by nails
(and an occasional claw)
2) They have binocular vision and their eyes face forward. This
aids them in judging distance accurately.
3) Primates have shorter snout allowing for a flatter appearing
face than quite a few other mammal groups although there
are exceptions to this rule, specifically Lemurs who have long
noses
4) Sellers argues that their olfactory sense is reduced and
prolongation of postnatal life periods
http://www.leeds.ac.uk/chb/lectures/anthl_08.html
5) They also have a, in terms of body size, a bigger and more
complex brain
6) The movement style also influences their anatomy
a) Those that travel on four feet usually have long backs
and narrow pointed chests (monkeys and prosimians)
b) Those that travel in a more upright posture have short
backbones and broad flat chests
c) However, O’Neil notes that all primates have a tendency
to be erect in terms of the upper body and some partake
of temporary bipedalism
7) most primates are arboreal, but some are terrestrial and most
excepting humans and gorillas sleep in trees
8) Most primates are diurnal, but there are exceptions such as
night monkeys
9) Primates are highly social animals and vocalize (whistles
hoots, grunts) and do displays (body language telling of the
emotional state of the primate)
10) O’Neil sees them as intelligent and adaptive to new
environments and many are omnivorous allowing them a
broad choice of foodstuffs
G) Sellers sees two problems with defining primates
First, there is not a unique characteristic that simply defines
a primate.
a) It involves a laundry list of similar characteristics and
tendencies –
b) Most of the characteristics are not even derived, but are
primitive features.
2) Second, many of the features are based on behaviors, or may
be dependent on the anatomy of the soft tissues
a) Since only bone is the main factor in fossilized remains,
identification is problematic.
H) According to Relethford the order of primates traditionally consisted of
two suborders, Prosimii (prosimians including tarsiers) and
Anthropoidea (Anthropoids-humans, monkeys and apes)
1) It should be noted that the new suborders of Strepsirhini for
Prosimians and Haplorhini will be mentioned for tarsiers,
monkeys, apes and humans
a) According to Sellers, the issue of the placement of
tarsiers still a major issue some in primatology
b) He further claims that it has been largely resolved by
the new suborders
c) However, he clearly thinks that they possibly should
have been put into a third suborder
2) Anthropoids are further divided into the Platyrrhini or the new
World monkeys and Catarrhini or old world apes or monkeys
http://www.msu.edu/~heckaaro/anthropoidea.html and
Relethford
3) Relethford notes that there is another method of classification
where tarsiers are grouped closer to anthropoids than
prosimians, but the traditional groupings will be used here.
Prosimians
A) Prosimians or more specifically Strepsirhini (since the tarsiers will be
discussed in this category as a somewhat separate group) can be
defined as “before apes”
1) Fleagle argues that the German halbaffen or “half-ape” is
more descriptive (Primate Adaptation and Evolution)
2) Rosen disagrees with this conceptualization (Introduction to
the primates)
B) Sellers claims that the First primate like mammals appeared during the
Paleocene Epoch (70 mya), and may have been around in the late
Cretaceous (that ended 65 mya—start 144 mya).
1) These are creatures are described by Sellers as early
prosimians.
2) O’Neil claims that these were the first primates to appear
C) This group preserves a morphology found among the primates of the
Eocene Epoch of about 50-40 mya
D) The prosimian group contains the lorises, lemurs and tentatively,
tarsiers
E) These creatures inhabited much of the world including North America,
however, they are only found in the wild in the Old World
F) Characteristics of Prosimians
1) Sept argues that they have whiskers and mobile ears and
black and white vision
1)
II.
http://www.indiana.edu/~origins/teach/A105/lectures/L6_A1
05_2004primates.pdf
a) However, Ruben argues that there is debatable evidence
of them having color or stereoscopic vision
2) Sellers argues that they have are good at vertical clinging
(cling and rest), slow quadrupedalism and leaping
(considerable distances)
a) If they fall on the ground they will either run bipedally or
hop or leap
b) The hindlimbs are greatly longer than the forelimbs
allowing arboreal qudrupedality (Ruben)
c) Ruben suggests that unusually “long and bushy tails”
(40) help to balance and propel them when leaping
3) Chirelli (Taxonomic Atlas of Living primates) claims that they
have a wet nose pad like a dog called a rhinarium
a) Turnbaugh claims that these creatures have a more
pronounced reliance on olfaction as is suggested by their
nose type and long snout
b) They also mark their territories by scent unlike other
primates
c) Tarsiers have dry noses—part of why they are difficult to
place
4) Sellers says they have dog-like faces
5) Many are seen as nocturnal and this allows them to avoid
competition with the diurnal apes and monkeys of the Old
World (Sept, O’Neil)
a) Ruben argues that some are crepuscular or especially
active at dawn and twilight
6) Turnbaugh argues that they have a special dental structure
known as a “dental comb” (Physical Anthropology and
Archaeology)
a) It is formed by the canines and lower incisors projecting
forward
b) The use for these structure is feeding and grooming
c) There is a sublingual organ called an accessory tongue
that is used to clean the dental comb
7) This group has a grooming claw on the second digit of their
feet also known as a “toilet claw” because it is used to
groom and remove dirt
a) It also serves as a back scratcher (Ruben)
8) Their ecological niche is the tropical rain forest and they are
mostly insectivores (Sept)
9) Fleagle argues that they have a small brain case
III.
10) Rosen claims that they have relatively large eyes, yet still
depend greatly on olfaction
11) Their dexterity is relatively poor because their digits act in
unison
12) In general they are omnivores and have multiple breast pairs
although only those on the pectorals are usually functional
G) The Lemurs-traditionally believed to be ghosts (Lemur is from the
Latin for “ghost”) by the natives are found only on Madagascar and
adjacent islands—the Comoros (O’Neil, Turnbaugh, Ruben)
1) Turnbaugh claims that there are 22 surviving species today
and that they vanished from other regions
2) They range in size from 5 inches to 2 feet
3) The larger lemurs have a varied diet they are in part
frugivores (fruit eaters) and foliovores (foliage) and buds
bark and shoots and are diurnal
4) The smaller ones are insectivores (Turnbaugh) and
faunivores—tree frogs and chameleons--(Fleagle), (and O’Neil
adds frugivores), solitary foragers (mouse lemurs) and
nocturnal
5) Some are arboreal and some terrestrial, some live in groups
and others are monogamous with the nocturnal ones being
almost solitary
H) The Lorises in Africa (2-3 genera) India and Southeast Asia (2 genera)
1) Turnbaugh claims that these are nocturnal, omnivores or
insectivores and all are arboreal
2) O’Neil claims that they are distinguished by locomotor
patterns
a) The move slowly and deliberately along branches using
quadrupedality and predators have difficulty spotting
them
b) Lorises can suspend themselves by their hind limbs and
use their hands to feed due to flexible hip joints
c) Their close relatives the Galagos are vertical clingers
who can hop with agility and travel 30 times the length
of their body
I) The Tarsiers are composed of 3 (Turnbaugh)-5 (Fleagle)-7 (O’Neil)
species are restricted to the island areas of Southeast Asia (Southern
Philippines, Indonesia)
1) They have large immobile eyes that Fleagle claims are
individually larger than the animal’s brain
2) Since they cannot move their eyes they have the ability to
turn their heads 180 degrees
3) Tarsiers are nocturnal insectivores and are monogamous
4) They lack a rhinarium (wet nose cover) and despite features
in common with prosimians (large ears, grooming claws, etc.)
5) They are closer in a biochemical sense to anthropoids
Anthropoids
A) Turnbaugh argues that 70 percent of the roughly130 species of
primates are monkeys
B) General features that differ from prosimians (Turnbaugh and others
140)
1) Larger body size (in general)
IV.
2) A larger brain, not only in size, but in size in relation to body
weight
3) A greater rounding to the skull
4) The placement of the eyes on the front of the favce permit
binocular vision
5) There is no rhinarium
6) An increased role for the parents in the lives of their offspring
7) Longer periods for gestation and maturation
8) Greater amounts of mutual grooming
New World Monkeys are called platyrrhini due to their flat noses “plat”
means “flat” and “rhine” is “nose”
A) They live in the tropical forests of Central and South America with a
small portion of Southern Mexico included and are comprised of 53
species
B) Characteristics
1) They have rounded nostrils set in a “broad fleshy septum”
(Rosen 65) that face outwards (Seller)
2) The grouping is composed of a wide variety of body types,
sizes and forms
3) There is little sexual dimorphism
4) All of them have tails and some are prehensile (grasping), but
they have a poorly developed finger and thumb grip
5) These are completely arboreal and have long limbs and
curved nails associated with locomotion in this environment
6) The mobility of the digits is less than that in Old World
monkeys
7) Their dentition is the same as in prosimians (2.1.3.3.) and
they lack a dental comb
a) They have been evolving in south America for over 30
million years in the absence of other groups like the
prosimians suggests an independent development of
these characteristics
8) New World monkeys do not possess cheek pouches that many
of the Old World monkeys possess nor do they have sexual
swellings
9) Many are herbivorous and they can eat nuts, fruit, insects and
tree gums
10) They are small ranging from 100 g to slightly over 10 kg
(Fleagle)
11) There is a larger and more convoluted brain (Seller)
12) They tend to be diurnal (only one species is nocturnal—owl
monkey
C) They can be grouped into two families, the Callithricidae and the
Cebidae
D) Callithricidae (tamarins and marmosets) are seen as the more
primitive of the two groups
1) They have thick fur and are mostly insectivores although
tamarins are frugavores
2) They do not have opposable thumbs making the grasping of
objects more difficult
3) Tamarins can use vertical clinging and leaping
4) Most are quadrupedal and their claws aid in climbing although
their big toes have nails and they may have prehensile tails
V.
5) They live in families as mated pairs or female and two males
and males are heavily involved in caring for the young
6) The birth of twins is common among this group
7) They lack the ability to change facial expressions (O’Neil)
8) Marmosets cannot maintain a stable temperature in their
body and it can vary as much as 8 ½ degrees Fahrenheit
9) It should be noted that some scientist further divide this
group into Atelidae for howler and spider monkeys and
muriquis
E) Cebidae
1) There are about 30 species from 1 to 2 feet in length
(Turnbaugh)
2) They weigh from 1.5 to 33 pounds (O’Neil)
3) This group is divided into 4 subfamilies (O’Neil)
a) Cebinae-capuchin or “organ grinder monkeys” can hunt
clams and crabs in swampy areas and Squirrel monkeys
b) Aotinae-titi and night monkeys (prosimian-like
springers)
c) Atelinae-spider and howler monkeys (largest of the
platyrrhines)
d) Pithecinae-sakis and uakaris (climbers)
4) Some are brachiators (swing through the trees) and have
prehensile tails (tactile pads aid in their ability to feel through
their tail—nerve endings)
a) Others are quadrupedal (Turnbaugh)
5) All but one species is diurnal (night monkeys are nocturnal)_
6) They have nails on all of their fingers and toes
7) They can live in troops of up to 500 or in nuclear family
groups
Old World Monkeys or the Family Catarrhini divided into the superfamily of
Cercopithecoidea—the other Superfamily of Hominodiae or apes will be
discussed later
A) Excepting humans they are the “most widely distributed of all living
primates (Turnbaugh et al. 141)
B) They live in Southern and Eastern Asia, (as far north as Japan), SubSaharan Africa, the Middle East and even the island of Gibralter just
south of Spain
C) They can live in tropical forests, mountains with heavy winter snows,
grasslands and semi-arid regions
D) O’Neil argues that there are 78 species associated with this group
E) Characteristics
1) Kelso (Physical Anthropology) claims that this group has tails
although they are not prehensile
2) They have only two premolars (New Worlders have 3)
dentition is 2.1.2.3. (the same as apes and man)
3) They do not brachiate and are quadrupedal
4) They can oppose their toes and thumbs with strength allowing
them to grasp objects
5) They have ischial callosities or calloused areas on their
buttocks of uncertain function
a) It is speculated that it is related to their sleeping in a
sitting position in trees and others (Turnbaugh) argue
that it is a “sitting pad” for them
6) They are mostly arboreal although some are terrestrial
7) They also have nostrils that face downwards (Catharrine)
(Rosen)
8) All are thought to be diurnal and they tend to be robust
(larger body parts ) unlike the New World Monkeys who are
gracile (slender, graceful)--Webster’s The free dictionary
9) They have sexual swellings where during the time of ovulation
for a female her skin and the external parts of her genitals
swell and turn red
a) This is not true of all Old World Monkeys
b) It tells males that the female is available at that time
c) Single births usually result
10) Although rare in new World species, sexual dimorphism is
common for these monkeys
11) Most have dagger like canines (Fleagle)
F) This group is divided into the subfamilies of the cercopithecinae or
cheek pouched monkeys and the colobinae or leaf eaters (Rosen)
1) The cercopithecinae are omnivores with a frugivore tendency
and have cheek pouches for food
a) It can shove large amounts of food into its mouth and at
the same time to be able to swallow at the same time
(part is stored)
b) These cheek pouches allow them to flee a feeding site
with at least some food
2) Most are found in Africa (Baboons, guenons and mangabeys)
although some are in Asia and Gibralter (macaques)
3) They range in size from 1 kg to 50 kg and are arboreal and
terrestrial
4) Forelimbs and hind limbs are of a similar size
5) The colobinae are leaf and seed eaters (they are the most
vegetarian of the primates)
6) They have enlarged salivary glands to help with the predigestion of food and they can even consume dead leaves
that have fallen off of trees (Rosen)
7) They have no cheek pouches and a ruminant like stomach,
which contains more acid than other monkeys(Fleagle)
a) However, Rosen refers to it as a pouched stomach
(O’Neil sacculated stomach) and it is not divided into
“essentially multiple stomachs” (88) like a true ruminant
8) They have shorter snouts than cercopithecinae
9) They can often lack a thumb (shorter thumbs and longer
fingers than the cercopithecines)
10) They have long hindlimbs
11) No sexual swellings and little sexual dimorphism
12) Although quadrupedal Rosen sees them as brachiators or
brachiating leapers (Turnbaugh as semi-brachiators)
13) They tend to be arboreal, although the Asian species tend to
be terrestrial
14) They have very long tails that may help them maintain their
balance as they move through the trees
15) They have very odd nose shapes—proboscis monkeys where
males have a Pinnocchio like nose (O’Neil) -- (sexually
dimorphic—Rosen)
VI.
Apes or the family Catarrhini divided into the superfamily of Hominoidea
(which also includes humans
A) General information
1) The hominids are seen as one of the smallest families for
mammals with only seven living species (Jenkins, “Evolution,
dispersal, and discovery of the great apes,” World Atlas of
the Great Apes and their conservation Caldecott, Miles eds.)
2) Six of the species live in wooded areas in the tropics and all
are threatened with extinction (the seventh group is humans)
3) Geographically, the gibbons and the orangutans reside in
Southeast Asia,
4) Bonobos, chimpanzees, and gorillas live only in Africa
B) Characteristics
1) O’Neil claims that the apes (and, of course, humans) are
different from other primates because they lack an “external
tail”
a) Actually they do have the remains of one in two bone
structures of the lower spine, the coccyx and sacrum
2) The dental formula for the apes is 2.1.2.3. (Fleagle)
3) Apes have broad nasal regions and palates and have large
brains with enhanced cognitive abilities (Fleagle, Turnbaugh)
4) They have long upper arms
5) In terms of foraging groups Fission (division) and Fusion
(coming together) seem to be common
6) They are generally larger than monkeys (except gibbons and
siamangs)--Turnbaugh
7) Apes have a shortened trunk and there are differences in the
musculature and position for the shoulder joint
8) Their behavior is more complex than that of the monkeys
9) There is a higher level of dependency and development for
infants and a longer gestation and a longer period to first
reproduction (Turnbaugh, Fleagle)
C) The super family of Hominoidea is subdivided into two families, the
Hyblobatidae and the Pongidae
1) The Hyblobatidae family contains gibbons and siamangs
(Kelso)
2) The Pongidae contains orangutans, chimpanzees and gorillas
3) It should be noted that the orangutans differ from the
Pongidae and that they should be seen as being between the
two groups (Relethford)
4) The Pongidae are, specifically, the chimpanzee, gorilla and
bonobo groups are the most closely related to humans
5) Relethford notes that revised taxonomy argues that the
Hyblobatidae remain a separate family from what is now the
family Hominidae
6) The Hominidae family is subdivided into 3 subfamilies
a) The Ponginae—the Orangutan
b) The Gorillanae—the Gorillas
c) The Homininae—subdivided into two tribes
1. The Panini—chimpanzees and bonobos
2. Hominini--humans
D) Hyblobatidae—gibbons and siamangs
1) There are 8 species of gibbon (O’Neil claims 12-13 species)
and they are the most successful in terms of numbers for the
living apes (Turnbaugh, Fleagle)
2) They retain many monkeylike features and have short snouts
and little sexual dimorphism (Fleagle)
3) Hyblobatidae are the smallest apes and weigh 13 (gibbon) to
25 pounds (siamang) and have a lengthened slender body of
about 3 feet in length (turnbaugh, ONeil)
4) They have very long arms, short thumbs, permanently curved
fingers and strong shoulder muscles used for brachiation
(90% of their locomotion—O’ Neil) and are strictly arboreal
(Reynolds, The Apes)
5) They are also largely frugivores, but can also be foliovores
and insectivores
6) Gibbons protect their young, are monogamous and are
territorial
E) Pongidae
1) Orangutans
a) The only “great ape” in Asia and is notable for its
reddish brown hair
b) They are slow moving and arboreal (climbers and
hangers), although they can move on the ground when
needed (Turnbaugh)
c) They are largely frugivores, but may be foliovores or
insectivores on occasion and reside in the forest
d) Orangutans are usually solitary and are large with a high
degree of dimorphism
1. Males may weigh over 200 pounds, whilke
females are usually less than 100 pounds
(Turnbaugh)
2) Gorillas
a) These are the largest of the apes with an adult male
weighing up to 400 pounds, while the females can weigh
200 (Turnbaugh) although Relethford claims lesser
weights and have a high degree of sexual dimorphism
b) They are terrestrial and quadrupedal and walk using the
knuckles of their forelimbs for support
c) They are shy and gentle vegetarians and practice
polygyny
d) They tend to reside in tropical forests or Montane
environments
3) Chimpanzees
a) Males can reach 5.5 feet and weigh about 100 pounds,
while females may weigh slightly over 80 pounds and
are sexually dimorphic
b) They occupy a variety of habitats from rain forests to
dry savannas with few trees (and Montane environments
–Reynolds)
c) They knuckle walk, but the young may brachiate and
occasionally walk bipedally
d) They are 90 % vegetarian (O’Neil) and are seen as 70%
frugivore (Relethford) or 60% fruit and nuts and 21%
leaves (Fleagle) and they may eat meat as well
e) They live in large communities (50 or so) surrounding
closely bonded males, but are seldom all together at
once and are not monogamous (they switch mates)
f) Chimps are one of the few animals to use tools and live
in fission-fusion societies
4) Bonobos—sometimes referred to as pygmy chimpanzees
a) These are the least studied of the great apes and live
only in a small area of Zaire (central Africa)
b) Bonobos are more arboreal and less aggressive than
chimpanzees
c) Male female bonding is important possibly due the
increased frequency of copulation over other non-human
primates (sex is used to reduce tension and homosexual
sex is sometimes practiced)
d) There is some sexual dimorphism males weigh about 95
pounds and females weigh about 73 pounds (Relethford)
e) They are knuckle walkers, but can walk more easily
upright than any other ape
f) They are frugivores and foliovores and may eat meat
occasionally
PHYSICAL ANTHROPOLOGY 2301 Lecture
HOMINID ORIGINS –section 9
II.
Pre-Hominid and Hominid origins
L) Relethford notes that the age of the human species depends on how one
defines the term human
1) Turnbaugh and others see the original roots of the primate order as
going back to the beginnings of placental (in most mammals, it joins
the fetus to the maternal uterus and acts as the site of metabolic
exchange between them) mammal radiation 65 million years ago
a) This took place during the Paleocene Epoch (Tertiary Period) 65-54
Million years ago (TRANS. Primate Tree)
b) These mammals were plesiadapiforms or small primate like
mammals about the size of a cat (TRANS. TAXONOMY—note the
mammals, primates etc. descent to man)
c) They were quadrupedal, climbers more closely related to flying
lemurs than primates and who were ultimately not considered true
primates
d) They differed from primates in several ways
1. the front teeth have a large distance from the rest of the teeth
2. Their eyes are on the sides of their skulls rather than forward
facing like primate eyes
2)
3)
4)
5)
6)
3. They lack a postorbital bar (a bony ring separating the orbit of
the eye from the back of the skull in primates)
4. The hands and feet did not have the grasping ability of
primates
5. They also had claws instead of nails
The earliest identifiable primates are from the Eocene Epoch (55-34
million years ago) of the Tertiary period
3 Theories on the development of the first true primates
a) The arboreal model
1. This is the view of primate origins that hypothesizes that
stereoscopic vision (3 dimensional view) and grasping hands
first evolved as adaptations for moving around trees
b) The visual predation model
1. This is the view of primate origins that hypothesizes that
stereoscopic vision and grasping hands first evolved as
adaptations for hunting insects along branches
c) The Sussman model
1. This suggests that grasping hands are an adaptation for
efficiently eating the fruit that grows at the end of long
branches (it does not explain stereoscopic vision)
Relethford suggests that the first “true” primates arose about 50-55
million years ago
a) these forms possessed stereoscopic vision, grasping hands and
other primate characteristics
b) They also possessed a postorbital bar
it has been certified by scientists that these primates were: (TRANS.
Primate Tree)
a) definitely primates
b) widely distributed due to adaptive radiation associated with a
warming climate and related environmental changes (almost 200
different species) (TRANS. CLIMATE 2)
c) mostly extinct by the end of the Eocene
d) It should be noted that it is uncertain if they were prosimians
(lemurs etc.) or of anthropoid origins (monkeys etc.)
e) It should be noted that Campbell and Loy see them as prosimians
and that they were arranged into two extinct families the Adapidae
and Omomyidae
During the Oligocene (34-22.5 million years ago) or late Eocene (both
are in the Tertiary Period) the first anthropoids arose in Africa and
some of them “rafted” over to what is now South America
a) Anthropoids can be defined as the suborder of primates consisting
of monkeys, apes and humans (TRANS. ANTHROPOIDS)
1. Tattersall and others note that the main method for
distinguishing between apes and monkeys is that monkeys
have tails
b) Most of the fossils found relate to Old World Anthropoids (all
discovered in a single locality in Egypt the Fayum) (TRANS.
FAYUM Turn 192)
c) Relethford, however, suggests that most of the anthropoid fossil
evidence is found in southern climates in Africa, South America and
parts of Eastern Asia
d) The New world monkeys may have arisen from some of the old
World anthropoids, but the varieties became separate 35 million
years ago (TRANS. MONKEYS AND APES MAP)
1. It is suggested that these New World Monkeys arrived by
“rafting” across the ocean on clumps of shoreline removed by
storms
2. This idea is supported by present geological evidence
3. Evidence for the African origins of New World monkeys can be
summed up in terms of 3 reasons
a. no suitable anthropoid ancestors have been found in the
new world
b. there is evidence for rats rafting over from Africa
c. New World fossil evidence points to a close similarity with
African Anthropoids
e) The closest group to humans after 35 m.y.a. are the Old World
monkeys and apes
f) In the Oligocene epoch anthropoids had reductions in the snout
and nasal areas showing the importance of vision
g) The anthropoids of this era develop an enclosed eye socket (same
as modern anthropoids) and were small and arboreal
h) Anthropoids also began the switch from nocturnal (active at night)
to diurnal (active during the daytime) suggesting different agencies
for natural selection
i) It is also believed that social interactions increased because
animals can see each other at greater distances
7) During the Miocene period (22.5 to 5 million years ago) in the Tertiary
Period a great deal of evolutionary activity took place (Miocene
hominoid distribution Turn 193)
a) In Europe, Asia and Africa a diverse and highly successful group of
hominoids (apes and humans) emerged
b) Relethford claims that apes were more diverse than monkeys until
about 5-10 million years ago
c) After that time the number of ape species have declined
1. a possible reason for this is the slow reproduction rate of
modern apes
d) It should also be noted that during the Miocene there were many
more forms of hominoids than there are today—“the golden age of
hominoids”
e) A problem that arises is simplification due to the complex nature of
the evolutionary situation (4 issues)
1. For example, for many years paleontologists tended to think of
these fossil forms as either apelike or humanlike and used
modern examples as models
2. However, due to the small amount of hominoids remaining
these generalizations deny the uniqueness of the forms
3. Also one should not expect all fossil forms to be directly or even
particularly closely related to living varieties
4. The opposite of this should be expected with most lines
vanishing without descendents
f) Other key issues concerning hominoids of this era are that:
1. They are hominoids and, therefore, are more closely related to
the ape-human lineage than to old world monkeys
2. They are mostly large bodied hominoids more akin to
orangutans, gorillas, chimpanzees and humans than to smaller
bodied apes
3. Most of the Miocene forms are improbable ancestors of any
living (modern) form
4. There are no definite hominids (humans and extinct bipedal
relatives) yet discerned from any Miocene dated locale (all
confirmed members of this family come from Pliocene beds
5. However, if Miocene hominoid fossils represent the earliest
stages of hominid diversification the definition of them as
hominid must be based in dentition (dental records)
6. Various scientists have also pointed to characteristics such as
large brain size, bipedal locomotion and tool making as being
significant in what constitutes a hominid
7. It should be noted that not all of the characteristics developed
at the same time
8. This pattern where different physiological systems evolve at
different rates is called mosaic evolution
g) The earliest members of the hominid lineage date back to 7-5
million years (Miocene still) ago and can be referred to as
protohominids
1. Turnbaugh and others claim that a protohominids are the
earliest members of the hominid lineage
a. They are underrepresented in the fossil record (their
structure and behavior are reconstructed hypothetically)
2. at a minimum the expected behaviors of this group would have
been in line with modern chimpanzees
3. Recent news suggests (9/3/2004 Houston Chronicle) a chimp
sized human ancestor walked upright 6 million years ago
4. The claim in the newspaper is that this was far earlier than
anyone had been able to show before and that this idea is
breaking news published in 2004
5. However, in Relethford the origin of bipedalism is also placed at
6 million years ago
6. He also claims that the fossil remains that are mentioned
(Orrorin tugenensis) were discovered and labeled as a bipedal
hominid in Senut et al published in 2001
h) A brief summary of hominid evolution is offered on this
transparency (TRANS. SUMMARY VIEW OF HOMINID
EVOLUTION 24—pg. 329 text)
M) The First Hominids
1) Tattersall and Schwartz argue that what defines a hominid is some
aspects of the pelvic bones and sacrum and angle of the lower end of
the femur
2) They also list the curvature of the lower, spine and having twin
depressions on the upper end of the tibia where the femur sits
(TRANS. Figures 28,29,30) Others use simpler criteria such as
bipedalism
3) Relethford claims that the first hominids have been found only in Africa
which supports Darwin’s early idea that Africa was the birthplace of
hominids
a) He sees it as consistent with the idea that the closest living
relatives of humans are the apes in Africa
4)
5)
6)
7)
b) However, again this is not a “fact” merely the best scientific
evidence
1. At least one author from the People’s Republic of China
suggests that the earliest humans lived in what today is Tibet
2. Again this is dated material and may be propaganda, but it
points to the idea that it is merely the best available evidence
that points to “Africa” for human origins
The hominid line is believed to have separated from the African apes
(chimpanzee bonobo group) about 6 million years ago
The earliest evidence for hominids at this time are represented by the
genus Ardipithecus (means “ground ape”—Stringer and McKie) and
Orrorin
a) Relethford uses the term “possibly” to describe the evidence for
Orrorin, but an article in the Chronicle suggests that there is now
strong evidence of the linkage
b) These two had primitive apelike teeth were bipedal and lived in and
near the forested woodlands of eastern Africa
Ardipithecus Ramidus (Ramidus means “root” in the local Ethiopian
language) lived during the Pliocene epoch (check for 5.8 mil in Phys
Geol.) in the Tertiary period and existed about 5.8-4.4 million years
ago (Stringer and McKie)
a) many scientists (until fairly recently) believed that ramidus lived
very close to the “root” of the human family tree (divergence of
apes and protohumans)
b) It is suggested that the in the area of teeth this hominid was like
an ape, however one author suggests that the canines were
smaller than in currently living apes
c) the skull base was small indicating that it was lighter and easier to
balance in an upright posture
d) There was a significant degree of sexual dimorphism (suggesting
polygyny)
e) Evidence for bipedalism is rooted in the location of the foramen
magnum and examination of a toe bone
1. The foramen magnum is the large opening at the base of the
skull where the spinal cord enters (located more under the skull in
bipeds)
f) However, there is little indication of other than an ape sized brain
based on the examination of skull fragments
g) The cranial remains are also apelike and show many primitive
characteristics
h) Also there are apelike features such as small back (molar) teeth
with only a thin enamel coating on the crown (exposed part of a
tooth—the grinding surface)
1. These are features found on modern gorillas and chimpanzees
who generally eat soft foods such as fruit that require crushing,
but not a lot of chewing
i) This early hominid (food remains of squirrels etc.) did not stray far
from an arboreal environment
Another Early hominid is Australopithecus Anamensis from Kenya with
an age range of 4.2 to 3.9 million years ago (TRANS.
Austalopithecine sites)
a) The species name of anamensis is derived from the word “anam”
that means lake in the local Turkana language
b) This is the first one that Relethford sees as definitely being a
hominid, however, again if bipedalism characterizes a hominid then
Orrorin tugenesis is the first
c) It is implied by a tibia bone fossil that it was larger in size than the
aforementioned Ardipithecus ramidus and australopithecus
afarensis *to be discussed)
d) It is the first of the hominids to be assigned to the genus
Australopithecus which means “southern ape”
1. It achieved this name because the first of this genus was found
in South Africa (Dart) even though many come from East Africa
2. As late as 2000© there were only 2 genera typically in use for
hominids Australopithecus and Homo (TRANS. Human
Relationships)
a. This is an implied denial of complexity in terms of evolution
3. It should be noted that with the notable exception of
Ardipithecus many in the scientific community lump all early
African hominids into Australopithecus
4. Tattersall and Schwartz argue that the uniqueness of the robust
species demand their differentiation into a different genus
5. They argue that taxonomically this group could be embraced in
a taxonomic sense by the genus Paranthropus (TRANS. Figure
31 T&S)
6. However, this still does not suggest that the leftover
Australopithecus groups (afarensis, anamensis, africanus etc.
are closely related)
7. Tattersall and Schwartz argue that the leftovers may be united
with those placed in the genus homo
a. this is based on features such as a broadened and
shortened upper part of the pelvic bone and sacrum
b. other features are lower spine curvature and double
impressions on the upper surface of the tibia
c. a problem with the placement of the leftovers in the
hominid category is that in the opinion of Tattersall and
Schwartz there would be:
A) “muttering if not fuming (among their colleagues), at
the suggestion that we should recognize more hominid
genera”
8) Australopithecus afarensis was until recently the earliest hominid for
which sufficient diagnostic anatomical evidence was available
a) The species name is derived from the Afar region where the early
Hadar site is located
b) Fossils for this type have been found in Ethiopia, Tanzania and
Kenya most of which date between 2.9-3.9 million years ago and
are from the Pliocene epoch (tertiary period)
c) The first fossils of this type were found in Ethiopia and this fossil
collection contains the famous partial skeleton (40% complete)
known as Lucy
1. Lucy was named after the Beatles song “Lucy in the Sky with
Diamonds” suggesting potential ties between drug culture
(L.S.D.) and early hominids
2. Lucy is an important fossil because her completeness allows
anthropologists to study the relationships between the size and
shape of structures in a single individual
3. Lucy died and was fossilized about 3.2 million years ago
4. Lucy also is one of the smallest specimens of this species and
her anatomy combines ape and human characteristics
5. She was adapted to bipedalism, but had apelike characteristics
such as short legs and long arms, an apelike cranium and
dentition (TRANS. Anatomy of CHEWING)
a. However some scientists believe that Lucy was adapted to
both arboreal quadrupedality and terrestrial bipedality
d) This species is characterized by small brain volume, canine teeth
larger than those of all other hominids, but smaller than any living
ape
e) Some skeletal sexual dimorphism exists, but it only slightly
exceeds that seen in modern humans (larger sexual dimorphism
suggests polygyny)
1. This suggests that A. Afarensis may have been monogamous
(TRANS. MONOGAMY AND POLYGYNY)
f) Australopithecus afarensis fossils represent a population that
spanned more than 600,000 years in an ecologically diverse
habitat
g) Overall A. Afarensis is seen as an intermediate step between apes
and humans
h) Until recently it was thought that A. Afarensis was the only hominid
species known for the time period of 3-4 million years ago
i) In 2001, however, a new species of fossil hominid was proposed
called Kenyanthropus Platyops (“flat faced man from Kenya”) that
dates from 3.2-3.5 m.y.a
j) Like A. Afarensis its primitive features include a small brain, jutting
lower face, and small ear hole
k) However, it has derived features such as small molars, a flat face
and tall cheek region (
N) Later hominids
1) Robust Australopithecines consist of 3 species robustus (1-2 m.y.a.),
bosei (1-2 m.y.a.)and aethiopicus (2.5 m.y.a.) (TRANS. Figure 31)
2) The origin of the term robust comes from the idea that this species
had robust back teeth, jaws and faces in relation to other hominids
3) One of the interesting aspects of the robusts is that they bring up the
question of homoplasy (independent appearance of similar structures
in 2 or more lines of descent)
a) most agree that they are a branch of the human family tree that
branched and ended with A. robustus and A. Boisei
b) In relation to other contemporary hominid species they form one
branch or are monophyletic
c) However, the question arises if they are monophyletic then why do
the later species resemble homo in so many ways
d) The answer may lie in homoplasy
e) However, it is also possible that resemblances between A.
aethiopicus and the “later” ones is also due to homoplasy and that
the robust group is not monophyletic
4) Darwin never predicted the existence of this group and these
australopithecines are unlike anything living today
a) They walked on hindlimbs remodeled from the common pattern
seen in other primates to the unique configuration thought of as
being “human”
5)
6)
7)
8)
b) They had relatively larger brains than did apes or earlier humans
c) However, they had small canines and large molars, no foreheads,
enormous mouths and flat cheeks
d) They are often portrayed as our herbivorous cousins who made no
tools and became extinct at least a million years ago
e) However, Susman believes that there is some evidence of tool use
among this group
A. Robustus is known from only 2 cave sites in South Africa
(Kromdraai and Swartkrans) and neither site can be dated exactly
a) their masticating muscles were especially large as can be seen
from the attachment areas on their cheekbones and sagittal crest
b) Relethford sees the sagittal crest as a ridge of bone running down
the center of the top of the skull that serves to anchor chewing
muscles
c) Although robustus implies a large powerfully built body newly
discovered skeleton parts show that this hominid ranged in size
from as little as 62 pounds to 120 pounds
d) The available fossil material is too fragmentary to produce accurate
predictions of stature
A. Boisei is known from East African deposits in Ethiopia and Tanzania
a) as in robustus there is a sagittal crest and the muscles that move
the jaw are powerfully built
b) A. Boisei shares many traits with homo not seen in
australopithecus
1. The face is tucked under the brain case more although this
varies
2. The brain is 488 cc as opposed to 384 cc of A afarensis (larger)
3. However, Variation in jaws and faces is considerable suggesting
that sexual dimorphism was greater than recent homo
c) Until recently it was assumed that the body of Boisei was large
when in reality women were about 70 lbs. (4’1”) and males about
108 lbs. (4’6”)
d) Some evidence of tool use was found in the region E. Africa, but it
is generally assumed that the tools were associated with homo
A. aethiopicus is the least well known of the robust australopithecines
a) A. Boisei can be identified by many distinctive features in teeth
dated from between 2.2 and 1.8 m.y.a.
b) There are also isolated teeth from 2.7 to 2.2 m.y.a. that are robust
yet not A. Boisei and these are referred to as A. aethiopicus
c) The one great find of this group is referred to as the black skull
(nearly complete)
1. The black skull has a sagittal crest that peaks way back on the
skull (not forward as in A. boisei)
2. It also shows that the muzzle protrudes way forward , the jaw
joint is shallow and the brain case has about 100cc less than A
Boisei
3. All are traits of early primitive species such as a afarensis
(Lucy)
Australopithecus Africanus and Australopithecus Garhi are the leading
choices for our ancestors during the 3-2 million year ago time period
a) Africanus had a small brain and a large face, no sagittal crest and
the front teeth are not as small relative to the back teeth
1. Some anthropologists consider it an extinct branch in hominid
evolution
2. The interesting aspect to this species is that it played a
developmental role in how we think about hominids
3. Dart the examiner of the Taung child (fossil remains) claimed
his fossil as a “man like ape” that had taken a crucial step
toward being human
4. This is in contrast to Du Bois who described his find of Java Man
as Pithecanthropus or “ape-man” (for the missing link between
humans and apes)
5. Dart used his idea to propose not only a new genus and species
for the Taung child, specifically, Australopithecus Africanus
6. He also proposed a new family known as Homo-simiadae
b) A. Garhi (”garhi” means surprise in Afar) was discovered in
Ethiopia and may be the human ancestor instead of Africanus
1. It has a small brain with no robust anatomy and was a tool
maker (stone tools to break open bones for marrow)