Human evolution

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Human evolution

• Chapter 34

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Humans???
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Archonta

• 65 mya
• Small arboreal (tree-dwelling) mammals
• Large eyes
• Insect eating
• Nocturnal
• Gave rise to bats, tree shrews primates

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Primates

• 1. Grasping fingers toes
• Opposable thumb
• 2. Binocular vision
• Eyes are shifted in front
• 2 fields of vision help with depth perception

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Primates

• Initially insect eating
• Teeth adapted to eat plants
• Fewer number of teeth
• Snout length began to get smaller

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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

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Primates

• Lemurs lorises
• Madagascar, Africa, southern Asia
• Tarsiers
• Small nocturnal tree-dwellers
• Southeast Asia

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Lemurs
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Lorises
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Tarsiers
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Primates

• 2. Anthropoids
• Monkeys, apes, humans
• Diurnal active during the day
• Feeding fruits leaves
• Color vision evolved-daytime foraging
• Expanded cortex for improved senses

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Aye-Aye
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Spider monkey
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Anthropoids

• Oldest known anthropoid fossils
• About 45 mya
• Supports Tarsiers are prosimians
• Most closely related to anthropoids

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Anthropoids

• Live in groups
• Complex social interactions
• Care for young for extended time
• Nurturing development of brain

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Anthropoids

• New World monkeys (Americas)
• 30 mya migrated to South America
• Isolated
• Arboreal (tree-dwelling)
• Flat spreading noses
• Prehensile tails
• Helps hanging in trees

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Squirrel monkey
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Capuchins
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Anthropoids

• Old world monkeys
• Ground dwelling
• Some arboreal
• Nostrils come together
• Noses point down
• Toughened pads of skin to sit upon
• No prehensile tails

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Old world monkeys

• Baboons, mandrills, macaque

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Mandrill
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Baboon
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Pig-tail macaque
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Anthropoids

• 25 mya
• Hominoids (human line)
• Branched from old world monkeys
• 1. Hominins (humans)
• 2. Ape group
• Gibbons, Orangutans, Gorilla, and Chimpanzees

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Hominoids
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Chimpanzee
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Gibbon
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Gorilla
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Orangutans
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Apes

• Larger brain than monkeys
• Lack tails
• Long arms short legs
• Most larger than monkeys
• Except Gibbon
• Gibbons orangutans are arboreal

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Apes

• Gorillas chimpanzees highly social
• Behavior more adaptable
• Spread over Africa Asia
• None in NA SA

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Gorilla
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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

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Chimpanzee
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Compare Apes to hominins

• Common ancestor arboreal climber
• Hominins bipedal
• Walking upright
• Apes are knuckle walkers
• Support weight on fingers

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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

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Compare Apes to hominins

• Larger brain
• Capable of language
• Manufacture use tools
• Reduced jawbones jaw muscles
• Shorter digestive tract

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Primates

• Prosimians
• Anthropoids
• 1. New world monkeys
• 2. Old world monkeys
• 3. Hominoids
• Apes (Gibbons, Orangutans, Gorilla, Chimpanzee)
• Hominins

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Paleoanthropology

• Study of human evolution
• Misconceptions
• 1. Ancestors were chimpanzees
• Chimpanzees Hominins
• 2 divergent branches of hominoid tree

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Hominins

• 2. Lineage straight line to Homo sapiens
• Multi branched bush

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Hominins

• 3. Upright posture enlarged brain came together
• Upright position came first
• Enlarged brain coming second
• Mosaic evolution
• Different features evolved at different rates

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Hominins

• Why upright?
• Tools found until 2.5 mya
• Faster/less energy
• Pick fruits/carry food
• See over tall grass

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Hominins

• 10 mya climate became drier/cooler
• Savannas grasslands
• More time walking in open habitats
• Less time in trees

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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

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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

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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

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Australopithecus

• Lucy
• 1974-fossil discovered
• Afar region of Ethiopia
• A.afarensis
• 40 complete skeleton
• 3.24 mya

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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

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Australopithecus

• A. robustus
• Second stockier skeleton discovered
• Massive teeth jaw
• A. Boisei (after Charles Boise)
• Even more stocky- 2 million yrs old

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Older hominins

• 2002
• Earliest hominins
• Dated 6-7 million years old

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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)

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Homo

• 1960
• East Africa
• Homo habilis- handy man
• Fossils of earliest genus Homo.
• 2.5 to 1.6 mya
• Found with tools

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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

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Homo

• H. ergaster
• More sophisticated tools
• Smaller teeth
• Suggested cooked foods
• Fossil of adolescence male
• 1.5 meters tall, weighed 47 kilograms

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Homo ergaster
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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

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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

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Homo erectus

• Java Man Peking Man
• Fossils found in China
• H. erectus extinct 200,000 years ago

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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

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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

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Homo sapiens

• Humans spread to NA 13,000 years
• By 10,000 there were 5 million spread through the
  world.

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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