Hominin Forms APY 203
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This 7 page Class Notes was uploaded by Demaree Rios on Saturday March 26, 2016. The Class Notes belongs to APY 203 at University of Miami taught by William Pestle in Spring 2016. Since its upload, it has received 35 views. For similar materials see Principles of Physical Anthropology in anthropology, evolution, sphr at University of Miami.
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Date Created: 03/26/16
EARLIEST FORMS HOMINID EVOLUTION Record gets more patchy the further back you go in history Study this based on shared anatomy Sahelanthropus tchadensis Discovered 2001 in Djurab Desert of Northern Chad, this is weird because it comes from central Africa (far from E. and S. Africa), opened up possibility that lots more evidence exists in other parts of Africa 6-7 mya, when speciation event occurred between modern human and chimps occurred (Miocene) Mosaic of primitive ape features and derived hominin features Cranial capacity 320-380 cc, actually smaller than modern chimps Small canines (relative to extant apes) No/ greatly reduced diastema Thicker enamel than apes Orrorin tugenensis Discovered 200 in Tugen Hills, Kenya 6 mya Small amount of fossils recovered (12-13 fossils) Shows some terrestrially bipedal and some arboreal (long curved fingers) adaptations (although this is debatable) Large canines (for a hominin) Ardipithecus ramidus Discovered 2001, Middle Awash, Ethiopia 4.4 mya No honing complex (shearing of large upper canine with first lower premolar thus wearing down the surface of both teeth) Fully bipedal based on leg and pelvis but still retained arboreal ability/ behavior (longer arms) Curved pedal phalanges Opposable/grasping toe, more arboreal feature No diastema Shorter and more broadly flaring pelvis than great apes but not as much as hominins The environment of Ardipithecus Paleoenvironment study revealed that these earliest hominins lived in gallery forests, dense stands of trees with grassland Retention of these primate features allow arboreal living still AUSTRALOPITHECINES E and S Africa Hominids from 4.5 - .5mya Gracile Aust. (lightly built) Would seem to give rise to Homo Robust Aust. Would seem to have gone extinct Australopithecus anamensis Discovered 1995, E Africa 4 mya Teeth straight arranged, not curved orientation Smaller canines No diastema Thick enamel Tibial plateau is very flat, characteristic of a biped Post cranial anatomy looks like biped Autralopithecus afarensis E Africa Large number of fossils from several sites Associated w. Laetoli trail (Tanzania, near Olduvai Gorge) 2.5-4 mya Gracile 30 – 70 kg, small Small brain 450 – 500 cc 3.5’ tall Flat tibial plateau, biped Broad pelvis, biped Big toe in line with other toes maxilla; teeth curved (like hominin), diastema seen pronounced sexual dimorphism longer arms, arboreal tendencies but movement towards full bipedalism a little more curvature in teeth but not much [Lucy] 1974 Don Johansen Hadar Special bc relatively complete 3.5- 3.0 mya 3’-4’ tall Most likely a female Australopithecus africanus Gracile S. Africa 2-3 mya Similar cranial capacity 400-500 cc (~1/3 of modern humans) Prognathism; protruding jaw, snout Face still orientated directly in front of brain (later humans brain will rise more superiorly positioned above face) Post orbital constriction; behind the eye sockets the cranium constricts Curved dental arch, dentally looks more derived/ modern than A. afarensis However, rest of skeleton is more similar to that of a great ape, not as complete/ obligate bipedalism Prominent sexual dimorphism [Taung child] 1924, Ramon Dart in limestone Determined it was a child based on dentition (3-6 years old) Endocast; imprint of the brain that used to be there, replica of how brain was shaped, looking at this can start to roughly work out aspects of cognitive capability Paranthropus robustus Robust S. Africa Arrive somewhat later than gracile but overlap in time Slightly larger body size, cranial size not that different Very large teeth, esp. premolars and molars Large deep jaw Large masseter muscles attach from jaw all the way up to sagittal crest Flatter face, broad cheek bones Sagittal crest (ridge atop skull) All these suggest well adapted for eating rough large vegetables but also had a varied diet, exert biting force of 1500-2000 lbs./ sq. in. (humans is 500) Relatively small cranial capacity Fair degree of sexual dimorphism Paranthropus aethiopithecus E. Africa The Black Skull 2.5 mya Stained by manganese of soil it was found in Compound crest on back of skull Upper face projects Broad face Large palate, large zygomatic foramen Large area for back teeth These features place it between A. afarensis and Paranthropus Paranthropus aethiopithecus Paranthropus boisei Very robust fossils Sagittal crest, huge jaws Huge teeth Existing together When exist together they diversify and specialize so that not in direct competition with each other Robust specialize to thick vegetation…go extinct Shows hominin evolution is NOT progressive GENUS Homo 1.7 mya Fully bipedal Reduced size of molars Decrease in sexual dimorphism Change in limb proportions, longer legs Prolonged life history Increase in Body size; >100 lbs., Avg. 5’ 6” Considerable brain enlargement Expanded geographic range Appearance and modification of stone tools and complex material culture A number of diff hominin taxa living side by side at the same time Single-species hypothesis; there was only one species living at any one time Homo habilis Olduvai Gorge, Tanzania (E. Africa) 2.8-1.5 mya Brain getting bigger, facial skeleton starting to shift below brain (600-700cc) Dental arch more curved, molars getting smaller Reduction of prognathism Brain organization changes; Broca’s (speech) and Wernicke’s (understanding lang.) area in Left hemi of brain, may have been moving towards language and speech Debate over why lang would emerge; effective means of communicating culture, exaptation Technological Trends Oldowan tools Olduvai Gorge 2.5 mya Contemporous with H. habilis Simplistic looking but very effective in cutting through meat, cutting bone to get to marrow etc. Good for scavenger behavior/ life style Homo rudolfensis Debate over which skeletal features are important in distinguishing species so some count H. rudolfensis as diff species…lumpers (species are varied but still one species just diverse) splitter (divide into their own species) 2 different skull sizes Homo erectus/ ergaster 1.8 mya Lived alongside end of H. habilis Modern body morphology Curved arched jaw Small molars Longer legs Body weight/ stature approaching modern proportions Fair degree of Prognathism Small orbital ridge Body proportions more modern (looks a lot like living E. African humans) Longer limb length (good for heat dispersal) [Turkana Boy] 16-28 yr old 1.8 mya 5’6” tall Longer limb length (good for heat dispersal) [Acheulean tools] Tools look diff than Oldowan, reflective of changing brain/ cognition Preconceived, manufactured following a “blueprint”, standardizes shape, symmetrical about multiple axes (cognitively difficult to obtain) Ex. Hand axes, 1.6 mya and unchanged for over 1.5 mill yrs all over Afr, Eur, and Asia Earliest evidence of controlled use of fire, 1.5-1.6 mya E. Africa cooked food = extract nutrients better= brain growth, defense from larger predators, warmth… …hominins start to leave Africa to Asia and Eur. using these tools/ innovations Spread across OW, 1.8 mya Eurasia (Georgia) Dmanisi Relatively small brained (600cc) Primitive looking erectus Modern dental and post cranial features Found edentulous skull (no teeth, older individual) a number of his teeth had been gone for so long but still survived, suggests members of hominin groups were caring for one another *H. erectus vs. H. ergaster ; African, earlier primitive examples= ergaster while more derived, non-African = erectus *there are differences between African and Asian erectus, can never ultimately resolve variances without genetic evidence so have to use morphological features instead Homo antecessor? Spain May or may not be ancestor to Neanderthals, 1.2mya - 700kya Homo heidelbergensis/ rhodesiensis One species or two debates Mandible [heid] Skull [rhod] Brains bigger than erectus (1200 cc), bigger relatively and absolutely Very robust cranial bones Very pronounced brow ridges (seen in Neanderthals later on) Neanderthals 1850s, Neander valleys Many similarities to modern humans People start to question if Darwin’s concepts apply to humans Robust hominins, homo genus 200kya to 25-30kya Thick brow ridges Very large nasal apertures Generally flat-faced but project a little in mid facial region Very laterally rounded crania (debate) homo antecessor are just early Neanderthal Bigger brains than modern humans Bigger bodies than living humans Greater breadth of body Bodies well suited for cold climates when Eur and Asia were partly glaciated Diversity of body types have to do with environment/ climate Displaced by humans? An evolutionary failure? Around twice as long as humans have been Refined material culture Hyoid bone looks indistinguishable from modern human, capable of possessing complex language May have produced art Intentionally burying their dead Homo naledi 2013, cave sys in africa 1500 specimens of fragment of bone representing at least 15 diff individuals Based on foot, fully upright/ bipedal Sexual dimorphism Heavy body weight, greater stature Hands; thumb and metacarpals very derived/ modern but also retention in longer/ more curved distals(fingers) Small brain (450-500cc) Teeth/ jaws; fairly derived/ modern *no date, found imbedded in clays, no volcanic material, no flowstones (stalagmite/stalactites)…*
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