Early Human Evolution: Oldest Hominins Study for HO PDF

Early human evolution: Oldest hominins Human/ Hominin characteristics - Short life history - Talk and elaborate culture - Bicondylar angle in knee vs straight - Foramen magnum is in the center, under the cranium for balance vs towards the back of the skull - Lumbar lordosis: curves in...

Early human evolution: Oldest hominins Human/ Hominin characteristics - Short life history - Talk and elaborate culture - Bicondylar angle in knee vs straight - Foramen magnum is in the center, under the cranium for balance vs towards the back of the skull - Lumbar lordosis: curves in the spine for shock absorption vs vertebral column: c shaped spine, just one curve - Larger brain - Large molars with thick enamel - Small canines - Less prognathic face - Parabolic dental arcade vs u shaped - Arched foot with big toe aligned with the other toes vs flat foot with grasping big toe - Wide pelvis - Apes have a large diastema for large canines (most hominins don't have this) Sahelanthropus tchadensis - Oldest - 6-7 MYA: Molecular data indicates the last ancestor of humans and chimps - Foramen magnum under cranium showing bipedalism and the reason for why we think its a hominin O. tugensis - Large femoral head, high neck angle, similar to humans showing bipedalism and the reason for why we think its a hominin A. ramidus - Bipedalism?- pelvis, foot, skull + Climbing?- foot, hand - Less prognathic than chimps (skull) - Ilium adapted for bipedalism (pelvis) - Not a knuckle walker (hand)- curved fingers - Grasping toe, stiff foot for bipedalism? (foot) Early human evolution: Australopithecus A. anamensis- A. afarensis - A. anamensis is likely an ancestor to A. afarensis - Woody grassland - Prognathic face + Smaller brains + Wide cranial base like chimps - Somewhat smaller canines than chimps - Body size dimorphism (males larger than females)- showing competition - Features btw homo + pan in: shape of dental arcade, diastema, canine dimorphism, third lower premolar for sharpening upper canine  - Bipedal based on vertebrae, hip, knee, ankle, foot (footprints) - Arboreal?- some tree climbing ability - Skeleton known as Lucy - Combination of homo + pan postcrania features: homo features- bicondylar angle of femur, big toe not divergent (not shown in skeleton, based on footprints), broad+short pelvis and pan features- long arms, curved toes and fingers Laetoli footprints - Similar to human footprints (probably A. afarensis) - Evidence of bipedalism A. afarensis: Dikika (Dikika child) - Shows features of bipedalism + climbing - Unerupted teeth - 3 yr old brain is 75% adult A. afarensis size - Slower brain maturation (longer life history as humans) A. africanus (Taung child) - Foramen magnum position suggests bipedalism - Small brain (cranially like A. afarensis) - Challenged large brain first idea A. garhi - Stone tools found nearby (capable of making stone tools?) A. sediba - Youngest- latest occuring - Small body and brains - Small teeth (like Homo?) - Relatively long arms Paranthropus - “Robust australopiths”- Side branch of human evolution - Craniodental adaptations: Enormous premolars + molars (huge cheekbones for tough food), Large sagittal crest, Large temporalis muscles, Huge zygomatic arches - Postcranial adaptations: Bipedal - Stronger chewing teeth - Very large masseter muscles - Very large temporalis muscle - Large temporal fossa - Postcrania: Pelvis and foot bones are more human-like than ape-like, Body weight estimates are similar to Australopithecus, Greater sexual dimorphism than humans and chimps but not as great as gorillas and orangutans - 3 species: P. aethiopicus, P. robustus, P. boisei P. aethiopicus (Black Skull) - Oldest species of Paranthropus - Very prognathic - Possible ancestor of P. boisei and P. robustus - East Africa P. robustus - Craniodental adaptations for chewing (ex. Huge molars) - Less robust than East African species of Paranthropus - South Africa P. boisei (Zinj or Nutcracker Man) - Largest cheek teeth and least prognathic of Paranthropus - Tough, fibrous vegetation - East Africa Early Homo Characteristics of Genus Homo - Inc brain size but not body - Tool use?: not a good feature if other hominins are creating tools - Obligate bipedal?: H. habilis were still climbing - Less prognathic face - Smaller cheek teeth (premolars and molars) - Relatively larger anterior teeth - Less sexual dimorphism The Oldowan Toolmakers - Oldowan industry= simple stone tool production (Mode 1 technology) - Oldowan tools at Olduvai Gorge, Tanzania, made by Homo habilis (or Paranthropus boisei) - Mode 1 tools can be used for carcass, butchering and/or digging sticks Hunters or Scavengers? - Cut marks do not= hunting - Some bones have cut marks + carnivore bite marks - Early hominin too small + too poorly encephalized to hunt? Meat Eating? - Why did early hominins eat more meat?- Expensive tissue hypothesis: inc brain size has a metabolic cost Postcrania of Homo habilis - Small bodied - Australopithecus/ape-like proportions w/ arms long relative to legs- suspensory? - Hand: large distal phalanges (+thumb) like H. sapiens  - Foot: non-grasping big toe, longitudinal arch H. rudolfensis - Much larger cranium - Larger cheek teeth - Less prognathic Homo erectus, Out of Africa Homo ergaster/erectus - Bigger brain - Smaller cheek teeth and flatter face than Australopithecus - First to migrate out of Africa - Some refer to all African and Asian species as H. erectus while others call African forms H. ergaster H. ergaster skull - Primitive: no chin, postorbital constriction, receding forehead - Derived: less prognathic, taller cranium, larger brain, smaller jaws and teeth - Unique: pronounced brow ridge (supraorbital torus), occipital torus H. ergaster Postcrania - Modern human limb proportions - 5’4 ft tall (probably 6ft as an adult)- significantly larger (taller) hominin H. ergaster: Acheulean industry - Biface (hand axe) strategically designed Dmanisi Postcrania - Cranium of old man w/ one tooth (couldn’t chew well) Homo erectus - First fossil evidence for an ape-human transitional species - Large brain - Femur=bipedalism - Viewed as first evidence humans evolved from apes as Darwin predicted - Possible cranial diffs w/ H. ergaster include: sagittal keel Homo floresiensis: The “Hobbit” - Small brain w/ associated stone tools - No chin - Occipital torus - Slight sagittal keel - Supraorbital torus - Widest at cranial base - Pelvis australopithecus-like, long arms, primitive feet that lack an arch  - Tooth size is w/in the modern human range + much smaller than similar sized species of Australopithecus Appearance of Homo sapiens and their contemporaries Archaic H. sapiens - Large geographic distribution of ‘Archaic’ Homo and lots of morphological variations Bodo - Evidence of defleshing from tool marks on the zygomatic bone - Cannibalism? Ritual? Atapuerca - Midfacial prognathism - H. antecessor with strongly arched brow ridges like a neanderthal Levallois (prepared core) technique Mode 3 technology - Archaic Homo tools for large game hunting Homo (sapiens) neanderthalensis - Only found in Europe, none found in Africa - Western Eurasian population of H. heidelbergensis became adapted to the glacial conditions - Brain size overlaps & exceeds modern human range, elongate crania with sloping foreheads, double-arched brow ridges Neanderthal Morphology - Larger brain than H. sapiens! - Oblong skulls (less round than H. sapiens): Occipital bun - bulging back of skull, Large projecting face w/ brow ridge, large nasal opening for cold weather - Unique teeth: Taurodont tooth roots, Heavily worn incisors - processing meat or tearing away animal skins - Short and stocky-> cold weather adaptation - More robusts limbs w/ better developed muscle attachments - Body form is an adaptation for retaining body heat in cold climates Neanderthal Intelligence - Original idea of neanderthals lacking intelligence is no longer supported - Use Mode 3 tools - Large game hunters - Burial of dead = ceremonial? or to keep scavengers away? The Life of a Neanderthal - Short life span (under 45)  - Difficult lives: Arthritis, Worn teeth / gum disease, Healed fractures / injuries, Survival from such significant injuries suggests conspecific care - Gene flow from Neanderthals into ancestors of non-african people occurred before divergence of eurasian groups from each other (breeding with eurasians not africans) Modern Homo Sapiens - Large, round cranium with high forehead - Small face and teeth - Protruding chin - Less robust postcranial skeleton - Long limbs = for dispersing body heat in equatorial Africa? - Higher populations / densities than Neanderthals in Europe - Lived longer than Neanderthals. Passed on more knowledge? - Healthier = less evidence of disease and trauma than the bones of Neanderthals