4/23/2014 1 Course Business None Homo erectus 24/23/2014 2 Topics • Homo erectus – Morphology – Behavioral innovations – 1st out of Africa • Later Homo 3 Ardipithecus (?) Modern human Australopithecus anamensis Australopithecus afarensis Australopithecus africanus Paranthropus boisei Paranthropus robustus Paranthropus aethiopicus A. garhi Our current view of early human evolution Homo habilis Homo rudolfensis 44/23/2014 3 Homo erectus overview • Date range: 1.9-0.03 Ma • Geographic range: Africa, Caucasus, Indonesia, China, Western Europe (?) • Morphology: thick-boned and robust crania, bipedal post-crania • Adaptations: migration out of Africa; Acheulean technology 5 Eugene Dubois • Anatomy professor at Amsterdam University • First person to ever deliberately search for fossil humans • Surgeon in the Royal Dutch East Indies Army • Thought humans evolved in the tropics 64/23/2014 4 Pithecanthropus erectus (“upright ape-man”) Dubois did not find anything in Sumatra, but then found what he would call P. erectus in Java (1891) 7 Trinil 2 Homo erectus cranial morphology • Ancestral traits: – Post-orbital constriction – Lack of a true forehead – Broad and flat face – No chin • Derived traits (shared with Homo sapiens): – Smaller, less prognathic face (subnasal prognathism) – Higher skull – Smaller teeth 84/23/2014 5 Homo erectus cranial morphology • Compared to early Homo: – Larger brain size (640-1200 cc) – Robust, long/low cranium widest at the base • Unique, derived features (not shared with modern humans): – Large browridges (supraorbital torus) – Occipital and angular tori – Sagittal keel – Supraorbital sulcus – Cranial superstructures! 9 Homo erectus brain size 104/23/2014 6 Homo erectus cranial morphology 11 Sinanthropus pekinensis (“Chinese man from Peking”) • Discovered in 1929 at Zhoukoukian, China • Focus of human origins switches from Europe to Asia • This, and 8 other skulls, lost during WWII 124/23/2014 7 Homo erectus, Indonesia • Sangiran 17 and several other skullcaps dated to 1.7-1.0 Ma • 1000 cc • Cranial superstructures we expect from H. erectus 13 Homo erectus in Africa 144/23/2014 8 The earliest Homo erectus in Africa: an occipital bone • 1.8-1.9 Ma, Kenya • Thicker bone than australopiths • Larger brain case • Angled occipital • Large nuchal torus 15 KNM-ER 2598 KNM-ER 3733 Homo erectus 164/23/2014 9 WT-15000 “Nariokotome Boy” 17 What does WT-15000 tell us? • As an adult, he would have been tall (~6’ tall) • He had a long, linear build with long appendages (Bergmann’s and Allen’s rules) • 1st hominin to: – Have fully modern limb proportions – Be completely adapted to terrestrial bipedalism (long, efficient striding gait similar to modern humans) 184/23/2014 10 Homo erectus: a fully committed biped • Modern body size and proportions • Robust pelvis (broad and shallow) • Robust femur • No arboreal traits in the shoulder or thorax • Intermembral index approximately that of modern humans 19 Biogeography of Homo erectus 20 ?4/23/2014 11 Any Questions? 21 Sexual dimorphism in Homo erectus 224/23/2014 12 Is Homo erectus more than one species? 23 Are the African and Asian fossils the same species? 244/23/2014 13 Why split Homo erectus into two species? • Very specific Asian morphology that is different from African Homo erectus • Shouldn’t just group fossils together because of shared or similar brain size • Asian H. erectus • Africa H. ergaster 25 Why keep Homo erectus as one species? • More similarities beyond brain size such as cranial superstructures • There is no clear African morphotype • Wide geographic and temporal range should allow for more variation – Which evolutionary forces might be responsible for the variation? 264/23/2014 14 Current status of Homo erectus • 1 Ma from Middle Awash, Ethiopia • With newer fossil finds, it is becoming increasingly difficult to justify separating Homo erectus into two species (especially geographically) 27 Who is the likely ancestor of Homo erectus? • Homo habilis or Homo rudolfensis? – Neither really is satisfactory – Homo habilis has more robust features – Homo rudolfensis has a larger brain size 284/23/2014 15 Ardipithecus (?) Modern human Australopithecus anamensis Australopithecus afarensis Australopithecus africanus Paranthropus boisei Paranthropus robustus Paranthropus aethiopicus A. garhi Our current view of early human evolution Homo habilis Homo rudolfensis 29 Homo erectus Any Questions? 304/23/2014 16 Homo erectus behavior 31 Speed walking across Asia 324/23/2014 17 Dmanisi hominins 33 What factors allowed H. erectus to successfully leave Africa? • Extrinsic: environmental change – Spread of African habitats and animals • Intrinsic: behavioral change or adaptations – Large brain size increase – Body size increase – Adoption of monogamy (and pair-bonding) – Changes in stone technology – Use of fire – Hunting of large mammals (trophic level increase) – Increased longevity (grandmother hypothesis) 344/23/2014 18 What factors allowed H. erectus to successfully leave Africa? • Extrinsic: environmental change – Spread of African habitats and animals Evidence: Several large mammal groups found at all African sites missing from Dmanisi – Pigs, hippos, monkeys, crocodiles… Hypothesis rejected 35 What factors allowed H. erectus to successfully leave Africa? • Intrinsic: behavioral change or adaptations – Large brain size increase Evidence: Average brain size of Dmanisi hominins is 630 cc Hypothesis rejected 364/23/2014 19 What factors allowed H. erectus to successfully leave Africa? • Intrinsic: behavioral change or adaptations – Body size increase Evidence: Post-cranial remains from 4 individuals – Body size range = 88-110 lbs Hypothesis rejected 37 What factors allowed H. erectus to successfully leave Africa? • Intrinsic: behavioral change or adaptations – Adoption of monogamy (and pair-bonding) Evidence: Relatively high degree of sexual dimorphism – More than chimpanzees and australopiths Hypothesis rejected 384/23/2014 20 What factors allowed H. erectus to successfully leave Africa? • Intrinsic: behavioral change or adaptations – Changes in stone tool technology 39 Homo erectus stone tool technology • First found with Oldowan • Acheulean stone tools added around 1.7 Ma 404/23/2014 21 Acheulean
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