Hominin Origins and Evolution: Part 2Hominin Origins and Evolution: Part 2- The oldest hominin fossils, dating from ca. 7-4 mya, show some evidence for bipedalism, but also have many ape traitso They include the species of the genera Orrorin Sahelanthropus, and Ardipithecuso More evolved forms of hominin include species of the genera Australopithicus, Kenyanthropus, and Paranthropus, all of which were definitely bipedalo Many of these later hominins were “dead ends” and did not leadto humans- Thorough the 1970s, it was widely believed that the first hominins would be ape-like creatures with big brains- Would have enabled complex behaviors, like tool use, hunting, and even organized aggression against other hominins- Popularized in books and film- Also lead to widespread acceptance of fraudulent finds, like Piltdown man (human’s skull with an orangutan jaw)- Raymond Dart knew otherwise when he found the first Australopithecines in the 1920s- This was a small-brained creature with indications of human-like locomotion (again, downward oriented foramen magnum)- LUCY SETS THE RECORD STRAIGHTo The 1970s discovery of a 40% complete Australopithecine, nicknamed “Lucy”) provided definitive evidence for bipedalism from an early hominin with a skull not much bigger than a chimp’so 3.6 mya footprints at Laetoli in Tanzania corroborated skeletal data for bipedalismo “Humans were built from the ground up, not the top down”- ADAPTIVE SIGNIFICANCE OF BIPEDALISMo Evidence suggests that early bipeds lived in savannah habitat, with open country and scattered groves of trees Bipedalism allowed for better long-distance travel betweengroves, as well as greater line of sight, plus it was more efficient in hot, sunny environment With hands free, bipedal hominins could carry food back toplaces of safety- MORE EVOLVED FEATURED AFTER 2.5 MYAo After 2.5 mya, the Australopithecines diverge in both east and south African populations A line of so- called “gracile” forms And a line of so-called “robust” forms- HYPERVEGETARIANS?o The robust forms display a variety of derived features that suggest a diet of hard, tough, foods, thus open habitat Sagittal crest Massive cheek bones Massive molars Thick enamelo Other features Cranial capacity of ca. 520 cc P. boisei persisted in East Africa with members of genus Homo, until 1.2 mya2- GRACILE FORMo A. Africanus All finds from South Africa Ca. 2.5 mya Compared to robusts, faces are more lightly built and dished-out Lacks sagittal crest Smaller molars Reduced canines, but still dimorphic, cranial capacity of ca.450 cc Some members of this group are likely ancestors of humans- THE APPEARANCE OF GENUS HOMOo Divergence of Australopithecines and early Homo by 2.5 mya in east Africao Robust Australopithecines extinct at 1.0 mya- HOMO HABILISo First discovered at Olduvai Gorge, Tanzaniao 2.4-1.4 myao Larger cranial capacity (500-800 cc) and front teeth than Australopithecines, but smaller molarso Retained long arms and moderately prognostic face- PARATHROPUS vs HOMO HABILISo Two genera evolved alongside each other in East Africa for more than million yearso Homo habilis fitting niche of meat eating3o Clearly two separate feeding adaptations Paranthropus fitting hypervegetarian niche Homo habilis fitting niche of meat scavenging, foraging omnivore Impacted cranial capacities- HOMO HABILIS, “HANDYMAN”o Oldest known stone tool tradition, called Oldowano Simple flaked stone tools defined from 1.85 mya strata at Olduvai Gorge, Tanzania KNOW FOR QUIZo Also used by Ausstralopithecines- HOMO ERECTUSo Found in Africa, Asia, and Europe (first hominin to leave Africa)o 1.8 mya to 140,000 years agoo Arose during volatile climatic conditions of the Pleistocene epocho Physically and culturally variable across vast range- SKELETAL FEATURESo Larger and more robust than Homo habilis; body proportions similar to modern humanso Cranial capacity average exceeding 1000 cco Classic cranial features include low forehead, pronounced brow ridge, large anterior teeth, sagittal ridge, nucal torus, pentagonal rear viewo Shovel shaped incisorso Classic features most pronounced in Asian examples Homo ergaster?4- HOMO ERECTUS GETS THE CREDIT FOR FIRST SYSTEMATIC TOOL MAKING- ACHEULEAN STONE TOOL TECHNOLOGYo Formalized bifacial hand-axes, cleavers, and other tools used for over one million yearso Two stage process Blank preparation Shaping and thinningo Required good raw material, foresight, and planningo Reflects (symbolic?) communication of method and formo Bifaces NOT among classic Asian fossils-careful trick question on exam- CULTURAL MILESTONESo Hunting Olorgesailie, Kenya- Acheulean hand axes found in direct association withremains of large critters, including now-extinct giant baboons- Dates to ca. 800,000 BP- Hunters of Scavengers?o Control of Fire Evidence often ambiguous- Natural fires leave evidence that is easily misinterpreted as human- Includes patched of burned clay with stone tools in Kenya, circular arrangements of burned cobbles in Thailand, and layers of ash in China5- ARCHAIC HOMO SAPIENSo “transitional” forms between H. erectus and H. sapiens, dating between 400,000-40,000 B.Po Africa, Asia, and Europeo General characteristics Brain expansion Increased parietal breadth Decrease in molars Mixtures of erectus and sapiens traitso Include newly discovered Denisovans- THE NEANDERTHALSo Homo neanderthalensis or homo sapiens neanderthalensis?o Group of archaic sapiens with distinctive biological and cultural featureso Date from 250,000-40,000 B.Po Restricted to Europe and West Asiao “Classic” Neanderthals from Western Europe, coinciding roughly with last glaciation (75,000-10,000 B.P)- LA CHAPELLE-AUX-SAINTSo One of the chief sources of biased perspective on Neanderthalso Nearly complete skeleton in shallow graveo Described by Boule as bent-over, not fully erecto Misconstrued spinal osteoarthritis for normal posture Entire population characterized based on single individual- MOUSTERIAN INDUSTRY6o Prepared core technique began begun before Neanderthals, but elaborated on by themo Core trimmed around edges to produce disk shapeo Then large flake struck from one face (known as Levallois technique)o Flakes then shaped into number of specialized tools- SUBSTINENCEo Emphasis on hunting gameo Animal bones abundant at siteso Teeth, musculature of chewing show adaptation to