Human Evolution Final Study Guide Epochs of Cenozoic Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Paleocene Eocene o 65 mya o Stem primates o Mammalian adaptive radiation into early Eocene o 54 8 mya o Most important for evolution o Warm forests no ice o Lemur like prosimians adapids tarsier like and anthropoids Nocturnal forward facing eyes small growing brains swampy omomyids habitat Oligocene o 33 7 mya o Dry isolated forests cool polar ice forms o Anthropoid split Catarrhines and Platyrrhines o Wide spread extinctions Miocene o 23 8 mya o Evolution of apes o OWM 15 mya Bilophodant molars o Human lineage 6 mya Sahelanthropus Forest dwelling savannah forest woodland o Primate extinctions Pliocene o 5 3 mya o Hominidae family o Australopithecines subfamily o Early Homo and first tools o Increase in brain size Pleistocene o Ice Ages o Last of robust australopithecines o Homo habilis Homo erectus archaic Homo sapiens Neanderthals anatomical modern sapiens o 1 8 mya 10 000 Relative Dating placing artifacts in geological order without reference to its actual age Ex Fluorine dating method compares the accumulation of fluorine in animal and human bones from the same sight Absolute Radiometric Dating the determination of the age of an object with reference to a specific time scale Rely on the decay of naturally occurring radioactive elements or isotopes Potassium Argon Radiopotassium Isotope Potassium 40 Decays to Argon Calcium Material Dated Volcanic ash lava Potential Range age of earth Half life 1 3 billion years Dates layers of lava not fossil prominent in East Africa Can only be used on igneous rock not sedimentary rock Carbon 14 Radiocarbon Isotope Carbon 14 Decays to Carbon 12 Material Dated Wood charcoal shell Potential Range 50 000 years Half life 5 730 years Destroys fossils Relationship between Global Temperature and Major Primate Events Role of Climate Change during Eocene and Miocene Eocene 54 8 mya high temperatures widespread forests begin of climate change with ice formation at the poles increased food availability seasonally Miocene 23 8 mya severe drying extension of deserts into previously forested areas increased seasonality with food shortages Effect on Primate Evolution o Eocene First modern appearing prosimians lemurs tarsiers o Miocene Rise and fall of the apes Rise of the OW monkeys Hypotheses Associated with Primate Evolution Arboreal Hypothesis a safe but complex habitat o Prehensile hands and feet o Collins 1921 Visual Predation Hypothesis bug snatching capabilities and hand eye Angiosperm Radiation Hypothesis not insects but fruit drove early coordination o Cartmill 1972 primate evolution o Sussman 1991 Fayum region in the eastern margin of the Sahara Desert 37 29 mya Birket Qarun Lake Rodents bats hippos elephants crocodiles birds plants Prosimians General Trends of Evolution in Cenozoic Anatomical Trends for Primates o Grasping hands and feet o Nails o Convergence of eye orbits o Bony protection for the eyes o Expanded molars o Enlargement of the brain Australopithecines o Reduction of canine size dimorphism o Megadontia in premolars and molars o Thick enamel on molars o Diet of tough fibrous food o Loss of grasping toe o Reorientation of shoulders Early Homo o 2 5 1 6mya o Variable increase in brain size o Reduction in tooth size o Continued facial prognathism o Prominent brow ridges o Essentially modern locomotion Homo Erectus o 1 8 3 mya o Increasing brain and body size o Increasing complexity and dependence on stone tools o Nomadic or home base o Hunters scavengers or both o Use of control of fire o Human like life histories Bipedality Adaptation to different diets Sahelanthropus Stem Australopithecine 7 mya Chad Probably bipedal small brain curved phalanges wooded forested areas Stem Australopithecine Orrorin 6 mya Kenya Probably bipedal small brain curved phalanges wooded forested areas Facultative upright walker competent tree climber flexible lower back shortened but non modern pelvis Ardipithecus ramidus Stem Australopithecine Ardi 4 4 mya Ethiopia Bipedal Sagittal crest Small brain Large canines Lived in forested areas Australopithecus afarensis Lucy East Africa 1970s Ethiopia Tanzania Kenya 3 7 3 0 mya Habitat from riverine forests to open grasslands Bipedal No canine size dimorphism Adapted to each tough fallback foods No sagittal crest Megadontia Parabolic jaw Australopithecus garhi 2 5 mya Ethiopia Humanlike arm to leg ratio Grasslands lake shore Tool maker user Robust australopithecines East and South Africa At least 3 species Discovered 1930 Kenya 1985 east Tanzania 1960 east Oldivae Gorge Small brain 450 cc Major differences between modern humans and Australopithecines Largest teeth molars megadontia 2 1 1 mya Grasslands Taung child Large brain 1924 South Africa Taung Austalopithecus africanus 3 6 340 cc Growth rate similar to that of modern apes Savannah habitat Early Homo o Cranial case Modern cranial capacity 1 350 cc o Jaw Mary and Louis Leakey o Early discoveries of hominids in East Africa o 1972 o Oldivae Gorge 1 9 mya Homo habilis o 612 cranial capacity o East Africa o 1 9 1 8 mya o Smaller molar teeth o More gracile mandible o Oldowon tools Homo erectus o First hominids to leave Africa 1 8 mya East Africa Western Asia Indonesia Java China Western Europe Spain Italy Georgia o Brain size 2 3 modern o Modern post cranium o Extended development o Scavenger hunter o Big size of modern humans ish o Nomadic o Dextrous use and manufacturer tools hand ax Acheulian tools o Social o Cranial anatomy Brow ridge Thick bones Sagittal keep not attachment for temporalis muscle Occipital torus point ridge of bone at back of skull Long low skull Differences o Reduction in tooth size in H erectus o Reduction in face and jaw size relative to size of brain case in H erectus o Increase in brain size in H erectus o Increase in brow ridge size in H erectus o Increase in cranial bone thickness in H erectus o Increase in body size in H erectus o Reduction in arm length in H erectus o Increase in leg length in H erectus Neanderthals Northern European range Mousterian tools Anatomical Features o Large teeth still decreasing o Occipital bun o Retromolar space o Robust o Broader pelvis o Short lower arm and leg bones o Large brains Difficult births non flexible pelvis Genetic Data o Highest genetic diversity in modern Africans o Some mutations Metabolic disease Immune functions Autism and schizophrenia Developmental differences Large bodied