Human evolution Chapter 34. Humans??? Archonta 65 mya Small arboreal (tree-dwelling) mammals Large...
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Transcript of Human evolution Chapter 34. Humans??? Archonta 65 mya Small arboreal (tree-dwelling) mammals Large...
Archonta
65 myaSmall arboreal (tree-dwelling) mammals Large eyesInsect eatingNocturnal Gave rise to bats, tree shrews & primates
Primates
1. Grasping fingers & toesOpposable thumb2. Binocular visionEyes are shifted in front 2 fields of vision help with depth perception
Primates
Initially insect eatingTeeth adapted to eat plantsFewer number of teethSnout length began to get smaller
Primates
Split into 2 groups 40 million years ago1. Prosimians “before monkey”Common in NA, Europe, Asia & Africalemurs, lorises and tarsiersIncreased visual acuityFruit, leaves & flowers
Primates
Lemurs & lorisesMadagascar, Africa, southern AsiaTarsiersSmall nocturnal tree-dwellers Southeast Asia
Primates
2. AnthropoidsMonkeys, apes, humansDiurnal: active during the dayFeeding fruits & leavesColor vision evolved-daytime foragingExpanded cortex for improved senses
Anthropoids
Oldest known anthropoid fossilsAbout 45 mya Supports Tarsiers are prosimians Most closely related to anthropoids
Anthropoids
Live in groupsComplex social interactionsCare for young for extended timeNurturing development of brain
Anthropoids
New World monkeys (Americas)30 mya migrated to South AmericaIsolatedArboreal (tree-dwelling)Flat spreading nosesPrehensile tailsHelps hanging in trees
Anthropoids
Old world monkeysGround dwellingSome arborealNostrils come togetherNoses point downToughened pads of skin to sit uponNo prehensile tails
Anthropoids
25 mya Hominoids (human line)Branched from old world monkeys1. Hominins (humans)2. Ape groupGibbons, Orangutans, Gorilla, and Chimpanzees
Apes
Larger brain than monkeysLack tailsLong arms & short legsMost larger than monkeysExcept GibbonGibbons & orangutans are arboreal
Apes
Gorillas & chimpanzees highly socialBehavior more adaptableSpread over Africa & Asia None in NA & SA
Apes
Chimpanzee split from common ancestor about 6 myaGenes of human & chimpanzees similarShares 98.6% of DNAHuman Hgb only one aa different
Compare Apes to hominins
Common ancestor arboreal climberHominins bipedalWalking uprightApes are knuckle walkersSupport weight on fingers
Compare Apes to hominins
Vertebral column more curvedSpinal cord exits at bottom of the skull Rather than the backPelvis is more bowl shaped Pelvis bones curve forward to support more weightLegs are longer than armssupport more weight
Compare Apes to hominins
Larger brainCapable of languageManufacture & use toolsReduced jawbones & jaw musclesShorter digestive tract
Primates
ProsimiansAnthropoids1. New world monkeys2. Old world monkeys3. Hominoids
Apes (Gibbons, Orangutans, Gorilla, Chimpanzee)Hominins
Paleoanthropology
Study of human evolutionMisconceptions1. Ancestors were chimpanzees Chimpanzees & Hominins 2 divergent branches of hominoid tree
Hominins
3. Upright posture & enlarged brain came togetherUpright position came first Enlarged brain coming secondMosaic evolution:Different features evolved at different rates
Hominins
Why upright?Tools found until 2.5 myaFaster/less energyPick fruits/carry foodSee over tall grass
Hominins
10 mya climate became drier/coolerSavannas & 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 humansReduced size difference between sexes Gorilla & orangutan males 2X heavier than femalesHumans average male is 1.2X heavier
Hominins
Two major groups of HomininsGenus Homo (3-7 species)Genus Australopithecus Latin australo, meaning “southern” Greek pithecus meaning “ape”Approximately 7 speciesOlder genus-smaller brains
Australopithecus
1924 first hominins fossil foundSouth Africa Skull 2.8 million years oldA. africanusWalked fully erectHuman-like hands & teethBrain 1/3 size of a modern human
Australopithecus
“Lucy”1974-fossil discoveredAfar region of EthiopiaA.afarensis 40% complete skeleton3.24 mya
Australopithecus
Pelvis shape-femaleLeg bones-uprightTeeth-homininsHead shaped like an apeStood approximately 1 meter tallBrain no larger than a chimpanzee
Australopithecus
A. robustus Second stockier skeleton discoveredMassive teeth & jawA. Boisei (after Charles Boise)Even more stocky- 2 million yrs old
Older hominins
1994 EthiopiaDiscovered complete fossil skeleton4.4 myaMore ape like BipedalNew genus Ardipithecus ramidus (ardi means “ground”, ramid means “root”)
Homo
1960East AfricaHomo habilis- “handy man” Fossils of earliest genus Homo. 2.5 to 1.6 myaFound with tools
Homo
H. ergaster “workman”Fossils date 1.9 to 1.5 myaLarger brain (900cm3)Longer slender legsHip joints-walkingFingers short & straight Early ancestor to later species of Homo
Homo
H. ergaster More sophisticated toolsSmaller teethSuggested cooked foods Fossil of adolescence male 1.5 meters tall, weighed 47 kilograms
Homo erectus
First hominins to migrate out of AfricaColonizing Asia & EuropeLived 1.8 million to 500,000 years agoLarger than Homo habilis-1.5 metersLarger brain (1000 cm3)Sexual dimorphism similar to modern man
Homo erectus
Social speciesLived in tribes of 20-50 peopleDwelling in cavesHunted large animalsUsed flint for firesLived longer than any other species
Homo neanderthalensis
Neanderthals1856 in GermanyFossil dating 40,000 years oldLived in Europe 200,000 to 40,000 years ago Thick boned, heavy homininsProminent browBrain size of humansExtinct 30,000 years ago
Homo sapiens
Originated in Africa-DNA evidenceOlder species (H.ergaster or H.erectus) gave rise to H. sapiensOldest fossils dated 195,000 to 160,000 years in EthiopiaOldest 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.