Download Evolution - ClassNet

Anthropology:
Human Evolution and
Adaptations
Evolutionary Theory

Charles Darwin 1809-1882

Published Origin of the
Species (1859)

Galapagos Islands –
observed different species of
finches

Controversial !
Evolution



Evolution refers to change over time, or
transformation over time.
Evolution assumes that all natural forms
arose from their ancestors and adapted over
time to their environments.
There are numerous ways in which evolution
occurs, the most noted are Natural Selection
and Adaptation.
Darwin’s Theory – Natural Selection
1.
Heritability: Organisms inherit characteristics from
their parents
2.
Variation: there is a lot of variation within a species
3.
Environmental Fitness: Those traits that allow an
individual to survive to reproductive age – to pass
on to offspring
Darwin’s Finches

An example
of Variation
Peppered Moth UK –
example of natural selection

White and Black moths (Variation)

Food source for birds

Before Industrial Rev. most moths – white better camouflaged against white lichen
(Enviromental Fitness)

Industrial Rev – coal dust turned
environment black, now black moths better
camouflaged. Black moths now surviving
to reproduce and pass their colour to next
generation (Heritability)

Now, most moths are black (natural
selection)
Key Concepts in Evolution



Adaptation
Variation
Natural Selection –
–

random genetic mutations occur within an organism's
genetic code, the beneficial mutations are preserved
because they aid survival
Survival of the Fittest –
–
only the necessary characteristics survive – and the
species who acquire those characteristics will remain
and reproduce
Artificial Selection



Human breeders have produced dramatic
changes in domestic animal populations by
selecting individuals to breed.
Breeders eliminate undesirable traits
gradually over time.
Examples?
Evolution –
evidence


Physical Anthropologists
Look at:
1. Fossil, bone, stone
remains (using dating
techniques)
2. Microscopic analysis –
pollen, scratches on
bone
3. Experiments – flake
stone techniques
Human Evolution
Hominids
Human Evolution


Primate - Largebrained, mostly treedwelling mammals with
three-dimensional color
vision and grasping
hands. Humans are
primates.
Hominid: is any
member of the biological
family Hominidae (the
"great apes"), including
the humans, chimps,
bonobos, gorillas and
orangutans
The oldest hominids belong to the
genus Australopithecus:




Australopithecus
Australopithecus
Australopithecus
Australopithecus
afarensis
africanus (example)
robustus
boisei
Australopithecus afarensis

Our most ancient
ancestor is
Australopithecus
afarensis. They lived
roughly 4 - 2.75 million
years ago. " Lucy" is
the skeleton remains of
an Australopithecus
afarensis which has
made us aware of this
species.
Hominids - The Human Lineage





Homo Habilis
Homo Erectus (example)
Neanderthals
Cro-Magnons
Homo Sapiens
Homo Erectus


They inhabited the regions of
southeastern and eastern Asia until
approximately 300 000 years ago.
Europe, India, China and Indonesia
have all yielded evidence of Homo
erectus.
–
"Turkana Boy" was an African discovery,
which shows that Homo erectus had a
similar body size to humans. The
period that this boy lived in was 1.6
million years ago. Homo erectus,
according to some studies, made use of
fire and occupied caves.
Habitual Bipedalism

Bipedalism – to
habitually walk on two
legs. Humans only
primate with this
adaptation

What had to happen for
us to stand up straight?
Bipedalism continued

Structural changes required
for us to walk upright:
1.
S-shaped spine
Arched foot
Pelvis – shorter and wider
More gluteus muscles
Fewer head / neck muscles
– therefore a bigger brain
2.
3.
4.
5.
Advantages of being bipedal

Free hands for
carrying

Can walk longer
distances

Can have a
continuous good
view of
surroundings
Disadvantages of
being bipedal

Highly dangerous
birthing process

Offspring very
dependent and weak
because the skull must
grow outside of the
womb
Hominids and Brain Size

Humans
have the
largest
brain for our
body mass
compared
to other
mammals
Refinements in hand structure 
A fully
opposable
thumb gives
the human
hand its
unique power
grip (left) and
precision grip
(right).
Tooth size comparison
Hominid (human), Primate differences:
Primates
Social
structures
Dominance Hierarchies
Silverbacks and alpha
males in a group
Grooming
Related to the hierarchies
Stress release
Hominids /
Humans
Pair Bonding AND
Group Living
Humans are the only
primates to have both
social characteristics
simultaneously
Hominid (human), Primate differences
Primates
Reproduction Estrus cycle (in heat)
No choice of when to
mate
Who gets to mate when
ties into dominance and
grooming hierarchies
Hominids /
Humans
No estrus cycle
Choice in when to
mate
Hominid (human), Primate differences
Primates
Mother –
Infant
relationship
Long infant
dependency
compared to other
mammals
Important in learning
survival skills and
culture
Hominids /
Humans
Longest infant
dependency
period of all primates
Hominid (human), Primate differences
Primates
Communication
Facial displays, call,
touch
Hominids /
Humans
Speech centre in the
brain
Culture
Dagger Carvings –
Stonehenge
Horse in world's oldest painted
prehistoric cave, 15,000-10,000
BC Lascaux, France
Humanity and
our Variations

Our bodies are
essentially 50 000 years
old.

Now culture, not physical
evolution enables us to
adapt very quickly to a
changing environment

Race - Cultural construct
– does not physically
exist
Skin Colour - Legitimate Explanations for
Human Variation

Sunlight is the best source
of vitamin D (necessary for
healthy bones)

Light skin absorbs vitamin D
and burns more easily than
darker skin
Paler skin
is found in areas further from
the equator where there is
less sunlight (environmental
Fitness)

Skin colour (variation)
Skin Colour - Legitimate Explanations for
Human Variation

Darker skin provides better
protection from UV rays

Darker skin is found in areas
closer to the equator where
there is more and stronger
sunlight (environmental
Fitness)

Skin colour (variation)