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 cm 3 to about 1,300 cm 3 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 (900cm 3 ) 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 cm man 3 ) Sexual dimorphism similar to modern

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