Human Evolution Final Study GuideEpochs of Cenozoic: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene- Paleocene: o 65 myao Stem primateso Mammalian adaptive radiation (into early Eocene)- Eocene:o 54.8 myao Most important for evolutiono Warm, forests, no iceo Lemur-like, prosimians (adapids), tarsier-like and anthropoids (omomyids)  Nocturnal, forward-facing eyes, small, growing brains, swampyhabitat- Oligocene:o 33.7 myao Dry, isolated forests, cool, polar ice formso Anthropoid split: Catarrhines and Platyrrhines o Wide-spread extinctions- Miocene:o 23.8 myao Evolution of apeso OWM (15 mya) Bilophodant molarso Human lineage (6 mya): Sahelanthropus  Forest-dwelling- savannah, forest, woodland o Primate extinctions- Pliocene:o 5.3 myao Hominidae (family)o Australopithecines (subfamily) o Early Homo and first toolso Increase in brain size- Pleistocene:o Ice Ageso Last of robust australopithecineso Homo habilis, Homo erectus, archaic Homo sapiens, Neanderthals, anatomical modern sapienso 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 sightAbsolute (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 isotopesPotassium 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 rockCarbon 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 shortagesEffect on Primate Evolution: o Eocene: First modern-appearing prosimians (lemurs & tarsiers)o Miocene: Rise and fall of the apes, Rise of the OW monkeysHypotheses Associated with Primate Evolution:- Arboreal Hypothesis: a safe, but complex habitato Prehensile hands and feeto Collins- 1921- Visual Predation Hypothesis: bug-snatching capabilities and hand-eye coordinationo Cartmill 1972- Angiosperm Radiation Hypothesis: not insects, but fruit drove early primate evolutiono Sussman 1991Fayum: 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 feeto Nailso Convergence of eye orbitso Bony protection for the eyeso Expanded molarso Enlargement of the brain- Australopithecineso Reduction of canine size dimorphismo Megadontia in premolars and molarso Thick enamel on molarso Diet of tough, fibrous food?o Loss of grasping toeo Reorientation of shoulders- Early Homoo 2.5-1.6myao Variable increase in brain sizeo Reduction in tooth sizeo Continued facial prognathismo Prominent brow ridgeso Essentially modern locomotion - Homo Erectuso 1.8-.3 myao Increasing brain and body sizeo Increasing complexity and dependence on stone toolso Nomadic or home base?o Hunters, scavengers, or both?o Use of/control of fire?o Human-like life histories- Bipedality- Adaptation to different dietsSahelanthropus:- Stem Australopithecine - 7 mya- Chad- Probably bipedal, small brain, curved phalanges, wooded/forested areas Orrorin:- Stem Australopithecine - 6 mya- Kenya- Probably bipedal, small brain, curved phalanges, wooded/forested areas Ardipithecus ramidus:- Stem Australopithecine- “Ardi”- 4.4 mya- Ethiopia - Facultative: upright walker, competent tree climber, flexible lower back, shortened but non-modern pelvis - Bipedal- Sagittal crest- Small brain- Large canines- Lived in forested areasAustralopithecus 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 - Small brain- 450 cc- Humanlike arm to leg ratio- Grasslands, lake shore- Tool maker/userRobust australopithecines:- East and South Africa- At least 3 species- Discovered 1930- Kenya – 1985 (east)- Tanzania – 1960 (east) (Oldivae Gorge)- Largest teeth, molars (megadontia) - 2.1- 1 mya- Grasslands Taung child:- 1924- South Africa (Taung)- Austalopithecus africanus- Large brain- 3’6”- 340 cc- Savannah habitat- Growth rate similar to that of modern apes Early Homo:- Major differences between modern humans and Australopithecines:o Cranial case Modern cranial capacity 1,350 cco Jaw- Mary and Louis Leakeyo Early discoveries of hominids in East Africao 1972o Oldivae Gorge- 1.9 mya - Homo habilis:o 612 cranial capacityo East Africao 1.9-1.8 myao Smaller molar teetho More gracile mandibleo Oldowon tools- Homo erectus:o First hominids to leave Africa – 1.8 mya East Africa, Western Asia, Indonesia (Java), China, Western Europe, Spain, Italy, Georgiao Brain size 2/3 moderno Modern post craniumo Extended developmento Scavenger/huntero Big – size of modern humans (ish)o Nomadico Dextrous – use and manufacturer tools – hand ax Acheulian toolso Socialo Cranial anatomy: Sagittal keep (not attachment for temporalis muscle) Brow ridge Thick bones Occipital torus (point – ridge of bone at back of skull) Long, low skull- Differences:o Reduction in tooth size in H. erectuso Reduction in face and jaw size relative to size of brain case in H. erectuso Increase in brain size in H. erectuso Increase in brow ridge size in H. erectuso Increase in cranial bone thickness in H. erectuso Increase in body size in H. erectuso Reduction in arm length in H. erectuso Increase in leg length in H. erectus Neanderthals - Northern European range- Mousterian tools- Anatomical Features:o Large teeth, still decreasingo Occipital buno Retromolar spaceo