human evolution Flashcards
what are the nearest relative
chimps
shared traits are due to
- shared common ancestor
- convergent evolution
Gigantopithecus
• Roamed in Asia from the late Miocene until the middle Pleistocene
• Largest primate that ever lived– perhaps as large as
300kg-
Chimpanzee skeleton
1. Hindlimbs shorter than forelimbs 2. Long pelvis 3. Knuckle walking 4. Protruding face 5. Spinal cord and the vertebrae enter into the cranium posteriorly
Paleoanthropology
study of human origins
Study of fossils of primates – especially Hominoidea
• AND traits themselves differ in timing and rates of evolution
Ardipithecus group: Sahelanthropus
tchadensis
Chad • Thicker enamel • Reduced prognathism • Massive brow ridge • Foramen magnum under the skull – suggests bipedalism • Brain 320-380 cc
Ardipithecus group: Orrorin tugenensis
Kenya • Like chimps in some ways, humans in other ways • Chimp-like front teeth – slight diastema • Human-like molars – smaller – with thick enamel • Maybe bipedal
Ardipithecus group: Ardipithecus ramidus
Ethiopia • Discovered 1992 • Females 120 cm; 50kg • Limb proportions similar to quadrupedal Miocene apes • Rigid-like foot (derived?) • Grasping toe (ancestral) • Woodland dwelling • Male and female canines similar size
Australopithecus Group
Erect • Bipedal • Relatively long forelimb (ape-like) • Sexually dimorphic (chimp-like) • Small brains (chimp-like) • Intermediate teeth – slight diastema – reduced canine – thicker enamel than ape
Locomotory transition: arboreal suspensory to
bipedal
- Postural adaptation for feeding
- Thermoregulatory (reduce surface area for insolation)
- Energetics of movement over open ground
- Carrying objects
Australopithecus
afarensis
Lucy • 40% complete skeleton • Adult female • 105-150 cm; 29-42 kg • Sex dimorphic • Skull/dentition – small braincase – prognathism – reduced canine – little bit of a diastema • Pelvis broad & narrow • Femoral neck long • Femur slants inward → Early bipedal • Arms somewhat longer relative to legs than in humans → Probably slept & foraged in trees
Australopithecus africanus
First identified in 1924 • ‘Taung Child’ • S Africa • ‘Southern ape of Africa’ • Small brain case • Face slightly protruding below the nose • Teeth large but proportions more similar to modern humans • Reduced canines
Australopithecus sediba
2008
• South Africa
• Small brain
• Good biped
Paranthropus
S & E Africa • Bipedal • Small brains • Robust masticatory apparatus but not entire body • Small incisors • Reduced canines • Massive cheek teeth • Large masticatory muscle – as per bony attachment on sagittal crest and mandible
Earliest Homo: H. habilis and
H. rudolfensis (2.8 - 1.5 mya)
• East Africa • Forelimb proportions similar to A. afarensis • Hand bones more robust than later Homo • Slightly enlarged brain (wide variation & body size larger too) • Sexually dimorphic (males > females • Reduced facial size and smaller teeth
