Cranial Morphology of Homo Erectus

CranialCranial MorphologyMorphology ofof HomoHomo erectuserectus Alveolar prognathism Larger teeth than moderns Supraorbital torus Low forehead Postorbital constriction Occipital bun Thick cranial bones No chin Cranial capacity: 800-1100 cc (gradual increase) Africa 1.9 mya TheThe careercareer ofof HomoHomo erectuserectus China and Java 1.6 mya Europe after 1 mya Java, 35,000 years? Acheulean tools after 1.5 mya, fire after 1.3 mya Genus Genus Ho mo Australopithecus Few if any stone tools Stone tools Brain size close to Brain size much larger apes than apes Mainly vegetarian diet, Meat + high-end plant little processing foods IfIf II OnlyOnly HadHad aa BrainBrain .. .. .. What does it take? StayingStaying coolcool PROBLEM: Most mammals cannot remain active in tropical daytime Brain cooling presents extra challenge SOLUTIONS: Global cooling at time of Homo emergence Triple benefit of bipedal posture Sweat on hairless body 250 times more effective Altered arrangement of blood vessels cooling brain EnergyEnergy needsneeds ofof anan expandingexpanding brainbrain 20% energy for 2% of body mass Gut vs. brain – Both expensive – Mutually exclusive Reducing gut size – Depends on diet Meat? MeatMeat andand thethe BrainBrain Homo brain grows at fetal rate after birth Energetics of nursing – Baby higher on food chain – 10:1 efficiency drop Maternal nutrition Significance of meat HighHigh--PayoffPayoff PlantPlant FoodsFoods Roots – Abundant – Digging sticks – Nutritious if cooked Nuts, etc. Skills, processing (Did(Did gracilegracile AustralopithecusAustralopithecus everever eateat meat?)meat?) Stable isotope analysis of South African africanus fossils indicate C4 plants – Meat from grazing animals? A. garhi from Ethiopia: tools and cut bones KNM-ER 1808 Homo erectus/ergaster Leakey team, 1974 1808 East Lake Turkana, Kenya tibia Age: 1.7 million years Partial female skeleton displays pathological bone buildup, suggesting hypervitaminosis from eating carnivore liver. She must have been cared for during her long terminal illness. Normal erectus Hunters or Many species do both Hunters or What kind of scavenging? – Marginal scrounging? Scavengers?Scavengers? – Power scavenging? HuntersHunters oror Scavengers?Scavengers? Many species do both What kind of scavenging? – Marginal scrounging? – Power scavenging? – Blumenschine’s non- confrontational scavenging Louis Leakey – Experiments in low-tech hunting – Traps and snares “Mighty hunters” or opportunists? – rudolphensis and early erectus likely opportunists – Later erectus a “mighty” hunter? TorralbaTorralba andand AmbronaAmbrona Late Homo erectus 400,000 years ago Genus Genus Ho mo Australopithecus Sex dimorphism 100% Sex dimorphism 10-20% Males in group unrelated; Males related; stay in leave group at time of group sexual maturity Males competitive Males relatively less competitive Genus Australopithecus Genus Ho mo Humerofemural index 85- Humerofemural index 70- 95% 75% Bipedalism + arboreal Humanlike body shape capability; intermediate and fully dedicated body shape bipedalism Size,Size, proportionsproportions andand dimorphismdimorphism KNM-WT 15000 Nariokotome or “Turkana boy” Homo erectus/ergaster Kamoya Kimeu, Leakey team, 1984 West Lake Turkana, Kenya Age: 1.6 million years Cranial capacity: 880 cc The Turkana boy is the most complete of any early skeleton, and it has enabled scientists to learn much about Homo erectus/ergaster. It died in early adolescence but would have reached a height of more than 6’ at maturity, with a cranial capacity of 909 cc. TurkanaTurkana BoyBoy vsvs.. LucyLucy Rib cage? Body shape? Pelvic shape? Waist (gut)? Tibia & ulna? TheThe GreatGreat LifeLife--HistoryHistory ShiftShift Life History: Gestation, birth, weaning, developmental patterns, sexual career, life span, etc. Leakey: major shift in Homo Evidence: Dental growth rates, pelvic and skull measurements Australopithecus had short, chimplike childhood Homo pattern: – Slow body growth, fast brain growth – Adolescent growth spurt Brain growth from birth to adulthood: Ape 2x Australopithecus 2.6x Homo erectus 3.3x Homo sapiens 3.5x Genus Australopithecus Genus Ho mo Gestation period correlates Gestation period less than with brain size as in other half that predicted by primates general primate pattern Doubling of brain size from Tripling of brain size from birth to adulthood birth to adulthood Apelike dental growth Humanlike dental growth pattern pattern “Ape grade” life history “Human grade” life history: (age of weaning, sexual long childhood, adolescent maturity, life span, etc.) growth spurt, prolonged life span Diet, Niche, & Life History A Theory of Human Life History Evolution: Diet, Intelligence, and Longevity Hillard Kaplan, Kim Hill, Jane Lancaster, A. Magdalena Hurtado, University of New Mexico Evolutionary Anthropology, 9:4 (2000) pp. 156-184 • Relies heavily on hunter-gatherer studies • Inter-species comparisons • Life history theory • Human capital theory • Compatible with Lovejoy, Leakey • More remains to be done: Vague on evolutionary timing, species • Much can be added in terms of culture and language The Theory • Begins with ecological premises--the human adaptive niche (presumably from early Homo times if not before) Human Niche • “Humans are specialists in that they consume only the highest-quality plant and animal resources in their local ecology and rely on creative, skill-intensive techniques to exploit them.” • Allows them “to colonize all of earth’s terrestrial and coastal ecosystems.” Dietary Niches Food Types • Collected – Leaves, fruits, insects • Extracted – Nuts, termites, tubers • Hunted – Small game, birds, etc – Large game • [Major scavenging?] Learning and productivity Life History Trends • Investment in skills • Long childhood – Slow body growth – Rapid brain growth • Adolescent growth spurt • Extended life span – 2x chimpanzee – Post-reproductive women – Contribution to food supply – Labor and skills – Cultural “capital” Lower Mortality: Part of Extended Life Span • Group size • Food package size • Food sharing • Hunting skills and tools • Knowledge of animal behavior Food exchange • Male to female • Three generational flow, old to young • Support of reproduction • [Pair bonding and CSR?] Flow Chart Brain, intelligence, language • Selective pressure for… • Conditions for… • [Role of home base?] Genus Australopithecus Genus Hom o Lack of home base Home base Estrus, visual and olfactory Continuous sexual receptivity sexual cues and pair-bonding Hand-to-mouth food Food sharing, economic consumption exchange, provisioning Apelike intelligence Increasingly abstract thought (narrative binding) Apelike vocal tract; flat Increasing basicranial flexion basicranium Apelike call systems Language: gestures, mimesis, invented lexicon (eventually, syntax) Example:Example: FLKFLK--ZinjZinj ““livingliving floorfloor”” Olduvai Gorge, Mary Leakey Zinj skull found there Thousands of mammals bones – Open-country species – Cut marks & tooth marks Homo tibia Once near a lake Oldowan tools Manuports TheoriesTheories ofof SiteSite FormationFormation Home base? Animal activity? Water action? Routed foraging? Picnic site? Tool cache? Kill site? Scavenged carcass? Palimpsest? HomeHome base,base, anyone?anyone? Glynn Isaac vs. Lew Binford Site 50, 1.5 mya? Terra Amata, France 400 kya Safety Altering environment Warmth Extending daily activity Hunting & technology Social focus PrometheanPromethean FireFire Genus Australopithecus Genus Hom o Lack of home base Home base Estrus, visual and olfactory Continuous sexual receptivity sexual cues and pair-bonding Hand-to-mouth food Food sharing, economic consumption exchange, provisioning Apelike intelligence Increasingly abstract thought (narrative binding) Apelike vocal tract; flat Increasing basicranial flexion basicranium Apelike call systems Language: gestures, mimesis, invented lexicon (eventually, syntax) WhoWho talked?talked? Contours of skull, neck Reconstructed Australopithecus vocal tract is apelike – Could not make human speech sounds – High larynx Human larynx is low – Flexed basicranium erectus was transitional Turkana boy’s vertebra had small spinal foramen – Limited ability to control muscles for speech proto-language? (more later . .) FireFire andand speechspeech Larynx descends in Homo, for speech Susceptibility to choking Meat is a common culprit Meat is important for brain growth Cooked meat easier to swallow Viva Prometheus! TransitionalTransitional Homo:Homo: TheThe LateLate ErectinesErectines TheThe AwkwardAwkward AgeAge .. .. .. AtAt 11 myamya,, erectuserectus AtAt 100100 kyakya,, modernmodern sapienssapiens TheThe inin--betweenersbetweeners:: –– Cranial/facialCranial/facial morphologymorphology resemblesresembles erectuserectus –– GrowingGrowing cranialcranial capacity:capacity: 11001100--13001300 cccc WhatWhat toto callcall them?them? ProposedProposed namesnames EACHEACH HASHAS ITSITS PROBLEMSPROBLEMS .. .. .. ““LateLate HomoHomo erectuserectus”” ““ArchaicArchaic HomoHomo sapienssapiens”” ““HomoHomo heidelbergensisheidelbergensis”” –– DiverseDiverse within,within, andand fuzzyfuzzy atat thethe edgesedges –– AddsAdds anotheranother namename toto rememberremember –– ButBut gaininggaining favorfavor HomoHomo heidelbergensisheidelbergensis AA HomoHomo heidelbergensisheidelbergensis SamplerSampler Steinheim, Germany 250 kya 1200 cc Petralona, Greece 300-400 kya 1220 cc Mauer, Germany (Type Specimen) 400 kya Bodo, Ethiopia Atapuerca, Spain 600 kya 300 kya 1125 cc Kabwe (Broken Hill), Arago, France Zambia 400 kya 1166 cc 300 kya 1300 cc BoxgroveBoxgrove,, EnglandEngland 500 kya Homo heidelbergensis? Rugged tibia, Acheulean tools, evidence of big game hunting Similar 4-500 ky old European acheulean sites : – Torralba-Ambrona – Terra Amata – St. Acheul (Knox handaxes) The Family Blob H. sapiens Neanderthals H. heidelbergensis Homo erectus SpeciationSpeciationSpeciation.

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