Human evolution

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Human evolution

• Waikato university site
• http//sci.waikato.ac.nz/evolution/HumanEvolution.
  shtml

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Main points

• Rapid changes as new fossils are found and
  re-evaluated every year
• Human and chimp diverged about 7mya 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)

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Early (Miocene) apes

• Apes evolved in Africa 20 mya (proconsul)
• Monkey-like traits backbone, pelvis and
  forelimb
• 17mya 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
  Urang-utan) and in Africa (ancestors of African
  apes)
• human evolution\human_odyssey.pdf

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proconsul
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Earliest hominins already bushy lineage

• Orrorin tugenensis 6mya, 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,

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Orrorin femur-head6 mya
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Sahelanthropus tchadensis
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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
  375-550cc
• A garhi 2.5 mya, Ethiopia, 450cc cranial
  capacity,
• A. Africanus 3.2-2 mya, bipedal, 420-500cc
  cranium,

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A. anamensis
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Lucy
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Laetoli footprints
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Australopithecines robust (Paranthropus)

• All have sagittal crest, large jaw, heavy skull,
  thick enamel on molars
• P. robustus 2-1.5 mya, 530cc cranium, tough,
  coarse food, might have used tools
• P.aethiopicus 2.6-2.4 mya, heavy face, large
  crest, 410cc cranium,
• P. boisei huge molars, massive built face and
  jaw, highly specialised hard food diet

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Cut marks on bones evidence for animal
butchering using a tool
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Trends in human evolution

• Cranial capacity
• Bipedalism
• Skull dental arcade
• facial angle
• Sexual dimorphism
• Rib cage

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Bipedalism

• Appears very early- (Maybe up to 7mya)
• 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

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Cranial capacity

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

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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)

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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.

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Out of Africa
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Homo floresiensis

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

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Homo neanderthalensis

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

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Cultural evolution

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

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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 culturesharper,
  straighter edges, smaller flakes removed, worked
  from many sides, range of uses

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Oldowan tools
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Acheulian tools
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Tools (II)

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

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Mousterian tools
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Moustarian tool
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Upper palaeolithic industry

• Modern H sapiens
• Africa 40,000 12,000ya
• Wider range of material, regional variation
• Uses fishhooks, harpoon points, needles

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Neolithic spear head
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Neanderthal cave drawings
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