Human evolution Waikato university site http sci waikato

Human evolution Waikato university site http: //sci. waikato. ac. nz/evolution/Human. Evolution. shtml

Main points Rapid changes as new fossils are found and reevaluated every year Human and chimp diverged about 7 mya in Africa Put lineage is ‘bushy’, with many different species in existence at the same time Ancestors of modern humans evolved in Africa Homo erectus populations left Africa about 1. 5 mya and moved rapidly across Europe and Asia (out of Africa theory)

Early (Miocene) apes Apes evolved in Africa 20 mya (proconsul) Monkey-like traits – backbone, pelvis and forelimb 17 mya land bridges to Eurasia allow migration out of Africa and divered into at least eight groups 13 mya – major climate change in Eurasia. Apes that survived – in SE Asia (ancestors of Urangutan) and in Africa (ancestors of African apes) human evolutionhuman_odyssey. pdf

proconsul

Earliest hominins – already ‘bushy’ lineage Orrorin tugenensis – 6 mya, Kenya, bipedal, ape-like canines Sahelanthropus tchadensis – 6 -7 mya, Chad, might not be bipedal, ape-like skull and dentition, forest environment Ardipithecus ramidus – Ethiopia, 4. 4 -5. 8 mya, forest environment,

Orrorin femur-head 6 mya

Sahelanthropus tchadensis

Australopithecines - gracile A. anamensis – 4. 2 -3. 9 mya. Probably bipedal, ape jaw and teeth A afarensis (Lucy, foot prints) – 3. 9 -3 mya, fully bipedal, intermediate human-ape dentition, face and cranium ape like, cranial capacity 375 -550 cc A garhi – 2. 5 mya, Ethiopia, 450 cc cranial capacity, A. Africanus – 3. 2 -2 mya, bipedal, 420 -500 cc cranium,

A. anamensis

Lucy

Laetoli footprints

Australopithecines – robust (Paranthropus) All have sagittal crest, large jaw, heavy skull, thick enamel on molars P. robustus – 2 -1. 5 mya, 530 cc cranium, tough, coarse food, might have used tools P. aethiopicus – 2. 6 -2. 4 mya, heavy face, large crest, 410 cc cranium, P. boisei – huge molars, massive built face and jaw, highly specialised hard food diet

Cut marks on bones –evidence for animal butchering using a tool

Trends in human evolution Cranial capacity Bipedalism Skull – dental arcade facial angle Sexual dimorphism Rib cage

Bipedalism Appears very early- (Maybe up to 7 mya) Gradual change (walking, followed by running) Earlier genus – position of foramen magnum Evidence from pelvic structure, knee and foot structure H. erectus – very efficient movement – very narrow pelvic outlook Wider pelvic outlet (in Sapiens) might be adaptation to larger infant head size

Cranial capacity Gradual increase in cranial capacity v. Early Australopithecines similar to modern chimp (Around 400 cc) v. Later australopithecines about 550 cc v. Homo erectus – 510 -1225 cc (within modern range) v. Neanderthal (1450 cc) larger than Homo (1350 cc) reflect difference in body size.

Skull morphology Dental arcade from U (chimp) [with cheek teeth parallel] to V (human) Decrease in size of teeth (molars ) Decrease in crest and ridges (sagital – diet, nuchal – posture) Facial angle becoming flatter (to vertical in Homo)

Other trends Reduce sexual dimorphism Rib cage size and shape: Funnel (A. afarensis) Barrel shape (Homo) Funnel shape accommodates the large gut needed for a herbivore (eg – gorilla). Barrel shape and hips – indication of meat in diet.

Out of Africa

Homo floresiensis Discovered 2004, in Indonesia 18, 000 yo remains Tiny – adult female 1 m tall, cranial capacity 380 cc, Tool maker and user Mix of traits: v. Primitive – low cranium, brow ridges, bipedal (narrow pelvis) v. Advance - flat face, Theory – a dwarf form of H. erectus, a case of dwarfism on islands

Homo neanderthalensis 230, 000 -30, 000 ya, ice age, in Europe and middle east Robust and heavily built Cranial capacity – 1450 cc Skull – elongated, receding forehead, weak chin, large nasal cavity Complex tools (Moustarian) m. DNA evidence – not closely related to Homo sapiens

Cultural evolution Tools Fire Shelter Clothing Art Cooperative behaviour (hunting) Domestication of plants and animals

Tools (I) Only stone tools survive Chimps – modified twigs and rocks, learnt behaviour, regional culture, pre-meditation A. gahri – 2. 5 mya H. habilis - Oldowan culture [cobble stones, one or more flakes knocked of one side] H. erectus – Acheulean culture[sharper, straighter edges, smaller flakes removed, worked from many sides, range of uses]

Oldowan tools

Acheulian tools

Tools (II) H. sapiens (archaic) and H. neanderthalensis Mousterian tools v. Stone core is shaped before flakes are removed v. Range of uses v. Some have tang at the end that suggests a wood or bone handle

Mousterian tools

Moustarian tool

Upper palaeolithic industry Modern H sapiens Africa – 40, 000 – 12, 000 ya Wider range of material, regional variation Uses – fishhooks, harpoon points, needles …

Neolithic spear head

Neanderthal cave drawings