Transcript Photosynthesis

Human Evolution
CH 32 - Outline
Evolution of Primates
Mobile Limbs
Binocular Vision
Evolution of Early Hominids
Evolution of Later Hominids
Evolution of Early Homo
Modern Humans
Human Variation
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Human Evolution
Evolution of Primates
The evolution of primates is characterized by
trends towards:
Mobile limbs
Grasping hands
A flattened face
Binocular vision
A large, complex brain, and
A reduced reproductive rate
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Primate Diversity 3
Primate Diversity
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New World Monkeys
New World monkeys differ slightly from Old World
monkeys in several aspects.
The most distinction is the nose, which is the feature
used most commonly to distinguish between the two
groups. The scientific name for the New World
monkeys, Platyrrhini, means "flat nosed".
New World monkeys are the only monkeys with
prehensile tails—in comparison with the shorter,
non-grasping tails of the anthropoids of the Old
World.
Old World Monkeys
Old world monkeys are more
closely related to apes than
new world monkeys
Old World Monkeys
The Old World monkeys are native to
Africa and Asia today, inhabiting a range
of environments from tropical rain forest
to savanna, shrubland and mountainous
terrain, and are also known from Europe
in the fossil record.
Old World monkeys are medium to large
in size, and range from arboreal forms,
such as the colobus monkeys, to fully
terrestrial forms, such as the baboons.
Apes: African, Asia, and Human?
Human Evolution
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Mobile Limbs
Hands and feet
Most primates have flat nails
Sensitive pads on the undersides of fingers and
toes
Many also have both an opposable big toe and
thumb
Mobile limbs and clawless opposable digits allow
primates to freely grasp and release tree limbs
Evolution of Primate Hand
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Human Evolution
Binocular Vision
Stereoscopic vision
Depth perception
Allows primates to make accurate judgments
about distance and position of adjoining tree
limbs
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Binocular Vision
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Human Evolution
Primate Characteristics
Opposable thumb
Nails instead of claws
Single births
Binocular vision
Expanded, complex brain
Emphasis on learned behavior
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Human Evolution
Evolution of Primates
Prosimians were the first type of primate to
diverge from the human line
Surviving anthropoids are classified into three
superfamilies
New World monkeys
Old World monkeys
Hominoids
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Evolution of primates
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Evolution of Primates
Human Evolution
Evolution of Hominids
Proconsul is believed ancestral to hominids
Phylogenetic tree indicates humans are most
closely related to African apes
Genetic changes used as a molecular clock to
measure relatedness of different groups
Last common ancestor appears to have lived
about 7 mya
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Monkey Skeleton
Compared to Proconsul Skeleton
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Human Evolution
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Hominids
Hominid fossils:
Must have an anatomy suitable for standing erect
and walking on two feet
Bipedalism
Skeletal differences between humans and apes
largely because:
Humans are bipedal, while
Apes are quadrupedal
Adaptations for
Standing
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1. Location of spine in skull
2. Human spine is S-shaped;
ape spine is curved.
3. Human pelvis is bowl shaped;
ape pelvis is long and more narrow.
4. Humans femur angle in towards
the knees; ape femurs angle out.
5. Human knees can support more
weight than ape knees.
6. Human foot has an arch; ape foot
has no arch.
Human Evolution
Australopithecines
Australopithecines:
Evolved and diversified in Africa 4 mya
Possibly a direct ancestor of humans
Southern Africa
- Australopithecus africanus
Eastern Africa
- Australopithecus afarensis
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Human Evolution
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Australopithecus afarensis
The specimen was discovered
in 1974 at Hadar in the Awash
Valley of Ethiopia’s Afar
Depression by Donald
Johansson of the Cleveland
Museum of Natural History
Lucy is estimated to have lived
3.2 million years ago.[
The discovery of this hominid
was significant as the skeleton
shows evidence of small skull
capacity akin to that of apes
and of bipedal upright walk
akin to that of humans
Providing further evidence
supporting the view that
bipedalism preceded increase
in brain size in human
evolution
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Australopithecus afarensis
Named “Lucy” after the
Beatles song “Lucy in the
Sky with Diamonds”
Several hundred pieces of
bone representing about
40% of the skeleton
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Human Evolution
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Evolution of Early Homo
Homo habilis
 Dated between 2.3 and 1.4 mya
 May be ancestral to modern humans
 Skulls suggest portions of the brain associated
with speech were enlarged
 Ability to speak may have led to hunting
cooperatively and the advent of culture
Human Evolution
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Homo erectus
Homo erectus and similar fossils
Found in Africa, Asia, and Europe
Dated between 1.9 and 0.3 mya
Larger brain and flatter face than Homo habilis
Much taller than previous hominids
Thought to have first appeared in Africa and then
migrated into Asia and Europe
First hominid to use fire
Homo ergaster
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Human Evolution
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Evolution of Modern Humans
Most researchers believe Homo sapiens evolved
from Homo erectus
Multiregional Continuity Hypothesis
- Similar evolution occurred in many different places
Out-of-Africa Hypothesis
- H. sapiens evolved from H. erectus only in Africa,
and thereafter migrated to Europe
Evolution of Modern Humans
Which of these makes more sense and why?
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Human Evolution
Neanderthals
Neanderthal (H. neanderthalensis) skeletons
were first discovered in Germany’s Neander
Valley
Skeletons date back 200,000 years
- Massive brow ridges with protruding nose, jaws,
and teeth
- Heavily muscled
- Culturally advanced
 Manufactured
variety of tools
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Neandertals
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Human Evolution
Cro-Magnons
Oldest fossils to be designated H. sapiens
Modern humans who entered Asia and Europe
from Africa 100,000 years ago
 Made advanced stone tools
 Accomplished hunters
- Hunted cooperatively
 First to have language
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Cro-Magnons
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Human Evolution
Human Variation
Hypothesized that human variations evolved as
adaptations to local environmental conditions
Bergmann’s Rule - Animals in colder regions of
their range have a bulkier body build
Allen’s Rule - Animals in colder regions of their
range have shorter limbs, digits, and ears
Comparative study of mitochondrial DNA
Suggests human populations have a common
ancestor no more than a million years ago
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Ethnic Groups
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