Hominin 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 traits o They include the species of the genera Orrorin Sahelanthropus and Ardipithecus o More evolved forms of hominin include species of the genera Australopithicus Kenyanthropus and Paranthropus all of which were definitely bipedal o Many of these later hominins were dead ends and did not lead to 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 STRAIGHT o 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 s o 3 6 mya footprints at Laetoli in Tanzania corroborated skeletal data for bipedalism o Humans were built from the ground up not the top down ADAPTIVE SIGNIFICANCE OF BIPEDALISM o Evidence suggests that early bipeds lived in savannah habitat with open country and scattered groves of trees Bipedalism allowed for better long distance travel between groves 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 to places of safety MORE EVOLVED FEATURED AFTER 2 5 MYA o 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 enamel o Other features Cranial capacity of ca 520 cc P boisei persisted in East Africa with members of genus Homo until 1 2 mya 2 GRACILE FORM o 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 HOMO o Divergence of Australopithecines and early Homo by 2 5 mya in east Africa o Robust Australopithecines extinct at 1 0 mya HOMO HABILIS o First discovered at Olduvai Gorge Tanzania o 2 4 1 4 mya o Larger cranial capacity 500 800 cc and front teeth than Australopithecines but smaller molars o Retained long arms and moderately prognostic face PARATHROPUS vs HOMO HABILIS o Two genera evolved alongside each other in East Africa for more than million years o Homo habilis fitting niche of meat eating 3 o 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 Oldowan o Simple flaked stone tools defined from 1 85 mya strata at Olduvai Gorge Tanzania KNOW FOR QUIZ o Also used by Ausstralopithecines HOMO ERECTUS o Found in Africa Asia and Europe first hominin to leave Africa o 1 8 mya to 140 000 years ago o Arose during volatile climatic conditions of the Pleistocene epoch o Physically and culturally variable across vast range SKELETAL FEATURES o Larger and more robust than Homo habilis body proportions similar to modern humans o Cranial capacity average exceeding 1000 cc o Classic cranial features include low forehead pronounced brow ridge large anterior teeth sagittal ridge nucal torus pentagonal rear view o Shovel shaped incisors o Classic features most pronounced in Asian examples Homo ergaster 4 HOMO ERECTUS GETS THE CREDIT FOR FIRST SYSTEMATIC TOOL MAKING ACHEULEAN STONE TOOL TECHNOLOGY o Formalized bifacial hand axes cleavers and other tools used for over one million years o Two stage process Blank preparation Shaping and thinning o Required good raw material foresight and planning o Reflects symbolic communication of method and form o Bifaces NOT among classic Asian fossils careful trick question on exam CULTURAL MILESTONES o Hunting Olorgesailie Kenya Acheulean hand axes found in direct association with remains 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 China 5 ARCHAIC HOMO SAPIENS o transitional forms between H erectus and H sapiens dating between 400 000 40 000 B P o Africa Asia and Europe o General characteristics Brain expansion Increased parietal breadth Decrease in molars Mixtures of erectus and sapiens traits o Include newly discovered Denisovans THE NEANDERTHALS o Homo neanderthalensis or homo sapiens neanderthalensis o Group of archaic sapiens with distinctive biological and cultural features o Date from 250 000 40 000 B P o Restricted to Europe and West Asia o Classic Neanderthals from Western Europe coinciding roughly with last glaciation 75 000 10 000 B P LA CHAPELLE AUX SAINTS o One of the chief sources of biased perspective on Neanderthals o Nearly complete skeleton in shallow grave o Described by Boule as bent over not fully erect o Misconstrued spinal osteoarthritis for normal posture Entire population characterized based on single individual 6 MOUSTERIAN INDUSTRY o Prepared core technique began begun before Neanderthals but elaborated on by them o Core trimmed around edges to produce disk shape o Then large flake struck from one face known as Levallois technique o Flakes then shaped into number of specialized tools SUBSTINENCE o Emphasis on hunting game o Animal bones abundant at sites o Teeth musculature of chewing show adaptation to meat hide processing o Helps explain some unusual cranial features such as occipital bun and browridge o Wear on teeth reflect use as vice HARD TIMES o Without long distance projectile technology hunting game may have involved