Download chapter outline

CHAPTER 4
THE PRIMATES
CHAPTER OVERVIEW
This chapter introduces students to the study of living, non-human primates. It discusses the basic
classification of primates and all of the classes of living primates. It also examines the similarities and
differences between non-human primates and humans as well as the earliest primate species which lived
during the Eocene and Miocene.
CHAPTER OBJECTIVES
1.
Be able to discuss how humans are related to the other primates and the importance of analogies
and homologies in determining this relationship.
2.
Know the suite traits that are unique to primates.
3.
Understand what prosimians are, where they live, and how they are related to other primates.
4.
Know the differences between New World and Old World monkeys.
5.
Be able to identify and distinguish between the apes.
6.
Understand the threats facing endangered primates around the world.
7.
Be able to discuss both the similarities and differences between humans and the other primates.
8.
Be able to identify and distinguish between the Early Cenozoic primates and the Oligocene
anthropoids.
9.
Be able to identify and distinguish between the Miocene hominoid species.
CHAPTER OUTLINE
I. Our Place among Primates
A. Definitions of key terms
1. Taxonomy: the assignment of organisms to categories.
2. Hominoidea (hominoids): the superfamily containing humans and apes.
3. Phylogeny: genetic relatedness based on common ancestry.
B. Phylogenetic Classification
1. Organisms are placed in classifications, which are arranged hierarchically according to degree
of genetic relatedness.
2. Phylogenetic classification is a descending hierarchy of classifications, from most inclusive to
least inclusive.
3. Species are constituted by organisms whose mating produces viable and fertile offspring.
1
II. Homologies and Analogies
A. Homologies
1. Similarities that organisms share because of common ancestry are called homologies.
2. The presence of homologies is the principal factor in determining how organisms are assigned
to taxonomic categories.
B. Analogies
1. Analogies are similarities between species that are the result of similar adaptation to similar
selective pressures--analogies are not the result of common ancestry.
2. The process which leads to analogies is called convergent evolution.
III. Primate Tendencies
A. Grasping (precision grip, thumb opposability, nails instead of claws).
B. Smell to Sight (eye placement, brain organization, and color vision all reflect a primate emphasis
upon sight over smell--not that some of these features are not common to all primates in the same
degree).
C. Nose to Hand (increasing reliance on sense of touch as opposed to muzzle, whiskers for
information).
D. Brain Complexity (the brain areas devoted to thought, memory, and association are more
elaborate and proportionally larger).
E. Parental Investment (single offspring births combined with longer development periods stemming
from neotony).
F. Sociality (strongly associated with parental investment, cooperative social groups are selected for
in part because of the needs arising from primate parenting).
IV. Prosimians
A. Prosimians vs. Anthropoids
1. Prosimians and anthropoids constitute the two suborders of primates.
2. 30 million years ago, prosimians were driven from niches by better adapted anthropoids.
B. Lemurs and Tarsiers
1. Most of the remaining prosimians, by far, are lemurs.
2. These live only in Madagascar, which separated from Africa prior to the development of
anthropoids.
3. Tarsiers survived in Asia, where there are monkeys, by adapting to night conditions (monkeys
are not nocturnal).
V. Anthropoids
A. Vision
1. Evolutionary changes in vision probably occurred in response to the pressures of an arboreal
habitat.
2. Binocular, stereoscopic vision and color vision may have been selected due to the improved
depth perception it endows (locomotion, catching insects, identifying edible fruits).
B. The arboreal habitat (climbing, feeding) and the increasingly social environment (mutual
grooming, tool making) were likely factors in selecting for increased manual tactility.
C. Proportionately larger (than prosimians) brain mass and emphasis on memory and cognition were
likely selected for by the social environment.
2
VI. Monkeys
A. Platyrrhines and Catarrhines
1. There are two anthropoid infraorders: platyrrhines (flat-nosed, New World monkeys) and
catarrhines (sharp-nosed, Old World monkeys, hominoids).
2. Unlike hominoids, monkeys’ rear and fore limbs articulate from their bodies as do dogs’.
3. Most monkeys have tails.
B. New World Monkeys
1. New World monkeys’ traits: universally arboreal, some brachiate, some have prehensile tails
(among primates, a trait exclusive to the New World).
2. The brachiation of New World monkeys and the brachiation of gibbons constitute an analogy.
C. Old World Monkeys
1. Old World monkeys are both terrestrial and arboreal.
2. Significant distinctions existing between arboreal and terrestrial Old World monkeys include
size (arboreal monkeys are smaller than terrestrial monkeys) and sexual dimorphism
(terrestrial males are significantly larger and fiercer than terrestrial females, while little or no
such differentiation exists among arboreal monkeys).
VII. Apes
A. Old World Monkeys comprise the superfamily Cercopithecoidea, while humans and apes are in
the superfamily Hominoidea.
B. Hominoidea is subdivided into three families.
1. Hominids (humans and their fossil ancestors)
2. Pongids (“great apes”: gorillas, chimpanzees, and orangutan)
3. Hylobatids (gibbons and siamangs)
4. Recent biochemical evidence suggests that gorillas and chimpanzees are almost as closely
related to humans as they are to each other.
C. Gibbons
1. Gibbons are small, arboreal, mate for life, and produce few offspring.
2. Their principal mode of locomotion is brachiation.
D. Orangutans
1. Orangutans are relatively large (up to 200 pounds), solitary, and markedly sexually dimorphic.
2. Orangutans move between arboreal and terrestrial habitats.
E. Gorillas
1. Gorillas are large (up to 400 pounds), the most sexually dimorphic of all primates, and are
primarily terrestrial.
2. They live in relatively stable social groups, typically led by a mature silver-back male.
F. Chimpanzees
1. There are two kinds of chimpanzee: the common (Pan troglodytes) and the pygmy (Pan
paniscus).
2. The common chimpanzee is found in western central Africa and western Africa.
3. Size range is up to 200 pounds, and sexual dimorphism is proportionally the same as in
humans.
4. Chimpanzee social organization is relatively well-known, because of the longitudinal studies
done by Goodall and other primatologists.
3
G. Bonobos
1. Bonobos belong to the species Pan paniscus.
2. Bonobos live in the humid forests of the Democratic Republic of Congo.
3. Bonobo communities are female-centered, peace-loving, and egalitarian.
4. Bonobos frequently use sex to avoid conflict within the community.
VIII. Endangered Primates
A. Humans are the only hominoids that are not endangered.
B. Deforestation, poaching, and the capture of primates have all contributed to the demise of wild
primate populations.
IX. Human-Primate Similarities
A. Learning
1. Neotony and life in cooperative social groups allow primates to learn behavior from their
fellows, rather than relying only on genetically encoded behaviors.
2. Learned behavior has been observed in monkeys as well as apes.
B. Tools
1. Tool use allows primates to adapt to a wider range of niches more quickly than physiological
adaptation alone (although primates are not the only animals that use tools).
2. Wild chimps have been observed constructing tools.
C. Predation and Hunting
1. Hunting is a regular and normal component of wild chimpanzee behavior.
2. Hunting by chimps is both opportunistic and planned.
3. Wild chimpanzees have been observed hunting consistently, using cooperative techniques,
with some sex specialization (males hunt more than females).
D. Aggression and Resources
1. The capacity for hunting exists among many different primates, but expression of this
capacity can depend upon environmental pressure and opportunity.
2. Observations of chimps and orangutans indicate that aggressive behavior (“warfare,” in some
chimp cases) may increase when territorial encroachment occurs.
X. Human-Primate Differences
A. Sharing, Cooperation, and Division of Labor
1. Sharing and cooperation are common to most primates; however, humans do it much more
complexly.
2. Human foraging bands tend to have a sexual division of labor (e.g., men hunt, women gather);
other primates do not.
3. Homo sapiens is the only primate species that engages in food sharing consistently on a large
scale.
B. Mating and Kinship
1. Human females do not experience estrus.
2. Marriage and kinship are two exclusively, universally human systems that give identity and
stability to certain types of human relationships in a way that is absent from other primate
social systems.
4
XI. Chronology
A. The history of vertebrate life on earth is divided into three eras: Paleozoic; Mesozoic; and
Cenozoic.
1. Each era is divided into periods.
2. Each period is divided into epochs.
B. Anthropologists are concerned with the Cenozoic era, which includes two periods: Tertiary and
Quaternary.
1. The Tertiary period has five epochs: Paleocene; Eocene; Oligocene; Miocene; and Pliocene.
a. A wide range of small mammals, some possibly ancestral to primates, appeared during the
Paleocene.
b. Prosimian-like fossils abound in strata dating to the Eocene.
c. The first anthropoid fossils date to the late Eocene and the early Oligocene.
d. Hominoids became widespread during the Miocene.
e. Hominids first appeared during the late Miocene or early Pliocene.
2. The Quaternary period has two epochs: Pleistocene and Holocene.
XII. Early Primates
A. Arboreal theory
1. Primates became primates by adapting to life in trees.
2. Enhanced sight (depth perception)
3. Grasping hands and feet
B. Visual predation hypothesis (Cartmill 1972, 1992)
1. Binocular vision, grasping hands and feet, and reduced claws developed because they
facilitated the capture of insects.
2. Early primates first adapted to life in the bushy forest undergrowth and low tree branches.
C. Early Cenozoic Primates
1. The earliest primates date to the first part of the Cenozoic (65-54 m.y.a.).
2. The Eocene (54-38 m.y.a.) was the epoch of prosimians with at least 60 different genera in
two families.
3. Anthropoids branched off from the prosimians during the Eocene.
a. Anthropoid eyes are rotated more forward compared to prosimians.
b. Anthropoids have a fully enclosed bony eye socket.
c. Anthropoids have a dry nose separate from the upper lip.
d. Anthropoids have molar cusps.
D. Oligocene Anthropoids
1. During the Oligocene (38-23 m.y.a.), anthropoids were the most numerous primates.
2. The parapithecid family may be ancestral to the New World monkeys.
3. The propliopithecid family may be ancestral to Old World monkeys, apes, and humans.
XIII. Miocene Hominoids
A. The earliest hominoid fossils date to the Miocene epoch (23-5 m.y.a.).
B. Proconsul
1. Proconsul was the most abundant anthropoid in the early Miocene.
2. Its teeth have similarities with modern apes, but below the neck the skeleton is more monkeylike.
3. Their teeth suggest that they ate fruits and leaves.
4. Proconsul probably contained the last common ancestor shared by Old World monkeys and
the apes.
5
C. Later Miocene Apes
1. More than 20 species of primates have been discovered that date to the Late Miocene.
2. Middle and Late Miocene apes are often grouped into two families: Ramapithedidae and
Dryopithecidae.
3. There are at least two ramapithecid genera: Sivapithecus and Gigantopithecus
a. Sivapithecus is now believed to be ancestral to the modern orangutan.
b. The orangutan line appears to have separated from the one leading to the African apes and
humans more than 13 million years ago.
c. Gigantopithecus is the largest primate that ever lived, some standing over 10 feet tall and
weighing 1,200 pounds.
d. Since it died out around 400,000 years ago, it coexisted with Homo erectus.
D. The Late Miocene
1. ???
2. Toumai is the name given to the 6 to 7 million year old primate skull found in northern Chad.
a. It may be the oldest human ancestor found yet.
b. The skull belonged to an adult male with a chimp-sized brain (320-380 cm3), heavy brow
ridges, and a relatively flat, human-like face.
c. The find blends human and apelike features.
d. The find suggests that human ancestry was not confined to eastern and southern Africa.
XIV. Box: Saving the Orangutan
A. Dr. Birutá Galdikas has been working since the 1960s to study and preserve orangutans in
Indonesia.
B. Orangutans are on the brink of extinction largely due to habitat loss.
LECTURE TOPICS
1.
An illustration of homologies and analogies by using the various animals commonly familiar to
undergraduates is most effective for demonstrating that difference. Such discussion also serves
as the basis for explaining the importance of homologies in classification.
2.
The variety of primate social groupings or organization should be categorized and presented in a
simple tabular form for easy recall. The adaptive basis for the various forms should be made
explicitly clear, particularly for the differences among the categories of mated couples, single
male groups, groups in which relationships among female kin form the basis for social
organization (female-bonded groups), and groups in which relationships among males form the
basis for social organization (male-bonded groups; chimpanzees).
3.
The adaptive roots of sexual dimorphism (competition among males for sexual access to females,
in the case of most primates), both in external physical pressures and in social relations, should
be explained carefully. How such adaptive pressures might or might not apply to humans should
be considered.
4.
There have been a number of studies done which investigate the nature of sex relations among
nonhuman primates and attempt to draw some conclusions, for example, aboutthe origins of
monogamy and marriage, sexual violence, and the origins of the sexual division of labor. Any of
these issues is both interesting in its own right and useful as a case study illustrating the
possibilities and limits for making generalizations across species. In particular, studies of maleto-female violence among nonhuman primates can be particularly useful for discussions on the
“naturalness” of battering among humans.
5.
Discuss the patterns of hominoid evolution during the Miocene.
6
SUGGESTED FILMS
Primates
1997 53 minutes
There are 234 primate species, and it seems that the more that is learned about them, the more humans
come to understand themselves. Narrated by Armand Assante, this film explores the life of primates in
their natural habitats. It discuss the social order, family life, diet, and mating habits of different primate
species. A Discovery Channel Production.
Jane Goodall: A Life in the Wild
1990 31 minutes
This film presents the life and work of Dr. Jane Goodall. Through interviews with Dr. Goodall, we learn
why she became a primatologist and how she came upon some of her more important findings. From
Films for the Humanities and Sciences.
Washoe: Apes and Sign Language
1994 53 minutes
This film was made by the researchers who worked with Washoe and shows how Washoe acquired and
used sign language. From Films for the Humanities and Sciences.
The Ape: So Human!
1998 41 minutes
This film presents the experiments by Allen and Beatrix Gardner, Sue Savage-Rumbaugh, and other
primatologists related to chimpanzee behavior. Particular attention is paid to cognition, self-awareness,
memory retention, language use, social behavior, and mating practices. From Films for the Humanities
and Sciences.
Ancient Mysteries: Bigfoot
1994 50 minutes
Narrated by Leonard Nimoy, this film traces reports of Bigfoot sightings over thousands of years and
discusses the current state of Bigfoot research. Presented by A&E Home Video.
Sasquatch Odyssey: The Hunt for Bigfoot
1999 60 minutes
This film presents a history of the search for Bigfoot, focusing primarily on four well-known Sasquatch
researchers: Peter Byrne, John Green, Rene Dahinden, and Grover Krantz. Presented by Big Hairy Deal
Films and Gryphon Productions Ltd., West Vancouver, BC, Canada.
7