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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
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Human evolution Chapter 34
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
Primates • 2. Anthropoids • Monkeys, apes, humans • Diurnal: active during the day • Feeding fruits & leaves • Color vision evolved-daytime foraging • Expanded cortex for improved senses
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
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
Anthropoids • 25 mya • Hominoids (human line) • Branched from old world monkeys • 1. Hominins (humans) • 2. Ape group • Gibbons, Orangutans, Gorilla, and Chimpanzees
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
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
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