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Human evolution
Chapter 34
Humans???
Archonta
65 mya
Small arboreal (tree-dwelling)
mammals
Large eyes
Insect eating
Nocturnal
Gave rise to bats, tree shrews &
primates
Primates
1. Grasping fingers & toes
Opposable thumb
2. Binocular vision
Eyes are shifted in front
2 fields of vision help with depth
perception
Primates
Initially insect eating
Teeth adapted to eat plants
Fewer number of teeth
Snout length began to get smaller
Primates
Split into 2 groups
40 million years ago
1. Prosimians “before monkey”
Common in NA, Europe, Asia & Africa
lemurs, lorises and tarsiers
Increased visual acuity
Fruit, leaves & flowers
Primates
Lemurs & lorises
Madagascar, Africa, southern Asia
Tarsiers
Small nocturnal tree-dwellers
Southeast Asia
Lemurs
Lorises
Tarsiers
Primates
2. Anthropoids
Monkeys, apes, humans
Diurnal: active during the day
Feeding fruits & leaves
Color vision evolved-daytime foraging
Expanded cortex for improved senses
Aye-Aye
Spider monkey
Anthropoids
Oldest known anthropoid fossils
About 45 mya
Supports Tarsiers are prosimians
Most closely related to anthropoids
Anthropoids
Live in groups
Complex social interactions
Care for young for extended time
Nurturing development of brain
Anthropoids
New World monkeys (Americas)
30 mya migrated to South America
Isolated
Arboreal (tree-dwelling)
Flat spreading noses
Prehensile tails
Helps hanging in trees
Squirrel monkey
Capuchins
Anthropoids
Old world monkeys
Ground dwelling
Some arboreal
Nostrils come together
Noses point down
Toughened pads of skin to sit upon
No prehensile tails
Old world monkeys
Baboons, mandrills, macaque
Mandrill
Baboon
Pig-tail macaque
Anthropoids
25 mya
Hominoids (human line)
Branched from old world monkeys
1. Hominins (humans)
2. Ape group
Gibbons, Orangutans, Gorilla, and
Chimpanzees
Hominoids
Chimpanzee
Gibbon
Gorilla
Orangutans
Apes
Larger brain than monkeys
Lack tails
Long arms & short legs
Most larger than monkeys
Except Gibbon
Gibbons & orangutans are arboreal
Apes
Gorillas & chimpanzees highly social
Behavior more adaptable
Spread over Africa & Asia
None in NA & SA
Gorilla
Apes
Chimpanzee split from common
ancestor about 6 mya
Genes of human & chimpanzees similar
Shares 98.6% of DNA
Human Hgb only one aa different
Chimpanzee
Compare Apes to hominins
Common ancestor arboreal climber
Hominins bipedal
Walking upright
Apes are knuckle walkers
Support weight on fingers
Compare Apes to hominins
Vertebral column more curved
Spinal cord exits at bottom of the skull
Rather than the back
Pelvis is more bowl shaped
Pelvis bones curve forward to support more
weight
Legs are longer than arms
support more weight
Compare Apes to hominins
Larger brain
Capable of language
Manufacture & use tools
Reduced jawbones & jaw muscles
Shorter digestive tract
Primates
Prosimians
Anthropoids
1. New world monkeys
2. Old world monkeys
3. Hominoids
Apes (Gibbons, Orangutans, Gorilla,
Chimpanzee)
Hominins
Paleoanthropology
Study of human evolution
Misconceptions
1. Ancestors were chimpanzees
Chimpanzees & Hominins
2 divergent branches of hominoid
tree
Hominins
2. Lineage straight line to Homo
sapiens
Multi branched bush
Hominins
3. Upright posture & enlarged brain
came together
Upright position came first
Enlarged brain coming second
Mosaic evolution:
Different features evolved at
different rates
Hominins
Why upright?
Tools found until 2.5 mya
Faster/less energy
Pick fruits/carry food
See over tall grass
Hominins
10 mya climate became drier/cooler
Savannas & grasslands
More time walking in open habitats
Less time in trees
Hominins
Brain size tripled
400-450 cm3 to about 1,300 cm3 in
modern humans
Reduced size difference between
sexes
Gorilla & orangutan males 2X heavier
than females
Humans average male is 1.2X heavier
Hominins
Two major groups of Hominins
Genus Homo (3-7 species)
Genus Australopithecus
Latin australo, meaning “southern”
Greek pithecus meaning “ape”
Approximately 7 species
Older genus-smaller brains
Australopithecus
1924 first hominins fossil found
South Africa
Skull 2.8 million years old
A. africanus
Walked fully erect
Human-like hands & teeth
Brain 1/3 size of a modern human
Australopithecus
“Lucy”
1974-fossil discovered
Afar region of Ethiopia
A.afarensis
40% complete skeleton
3.24 mya
Australopithecus
Pelvis shape-female
Leg bones-upright
Teeth-hominins
Head shaped like an ape
Stood approximately 1 meter tall
Brain no larger than a chimpanzee
Australopithecus
A. robustus
Second stockier skeleton discovered
Massive teeth & jaw
A. Boisei (after Charles Boise)
Even more stocky- 2 million yrs old
Older hominins
2002
Earliest hominins
Dated 6-7 million years old
Older hominins
1994 Ethiopia
Discovered complete fossil skeleton
4.4 mya
More ape like
Bipedal
New genus
Ardipithecus ramidus
(ardi means “ground”, ramid means “root”)
Homo
1960
East Africa
Homo habilis- “handy man”
Fossils of earliest genus Homo.
2.5 to 1.6 mya
Found with tools
Homo
H. ergaster “workman”
Fossils date 1.9 to 1.5 mya
Larger brain (900cm3)
Longer slender legs
Hip joints-walking
Fingers short & straight
Early ancestor to later species of Homo
Homo
H. ergaster
More sophisticated tools
Smaller teeth
Suggested cooked foods
Fossil of adolescence male
1.5 meters tall, weighed 47 kilograms
Homo ergaster
Homo erectus
First hominins to migrate out of
Africa
Colonizing Asia & Europe
Lived 1.8 million to 500,000 years ago
Larger than Homo habilis-1.5 meters
Larger brain (1000 cm3)
Sexual dimorphism similar to modern
man
Homo erectus
Social species
Lived in tribes of 20-50 people
Dwelling in caves
Hunted large animals
Used flint for fires
Lived longer than any other species
Homo erectus
“Java Man” & “Peking Man”
Fossils found in China
H. erectus extinct 200,000 years ago
Homo neanderthalensis
Neanderthals
1856 in Germany
Fossil dating 40,000 years old
Lived in Europe
200,000 to 40,000 years ago
Thick boned, heavy hominins
Prominent brow
Brain size of humans
Extinct 30,000 years ago
Homo sapiens
Originated in Africa-DNA evidence
Older species (H.ergaster or
H.erectus) gave rise to H. sapiens
Oldest fossils dated 195,000 to
160,000 years in Ethiopia
Oldest fossils outside of Africa is
40,000 years old
Homo sapiens
Humans spread to NA 13,000 years
By 10,000 there were 5 million spread
through the world.
Homo sapiens
Only surviving hominins
Increasing brain size
Use tools
Symbolic language
Shape concepts out of experience
Transmit experience from one generation
to another
Change environment