Early Hominins

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Early Hominins

• Part 2

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AustralopithecinesThe earliest Hominins

• East African fossil finds
• 4-3 mya bipedal although these animals probably
  also were comfortable in the trees
• From Ethiopia, Tanzania, Kenya
• Great Rift Valley
• Environment has changed
• Hadar in the Afar depression of Ethiopia now dry,
  used to be wooded
• Laetoli in Tanzania bipedal footprints _at_ 3.6 mya
  in mud of a wetland area

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Maps of Africa (see http//81.0.149.237/frie_med
ier/Map_of_Africa.jpg and http//www.worldatlas.co
m/webimage/countrys/aflnd.htm)
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AustralopithecinesThe earliest Hominins

• South African fossil finds
• All the main finds from South Africa
• Taung child
• Raymond Dart in 1925
• The first Australopithecine ever discovered
• Australopithecus africanus
• Dates to about 3-2 mys
• Mrs. Ples, also A africanus confirmed the find
  was a bipedal hominid

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Maps of Africa (see http//81.0.149.237/frie_med
ier/Map_of_Africa.jpg and http//www.worldatlas.co
m/webimage/countrys/aflnd.htm)
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Gracile Australopithecines A anamensis

• Australopithecus anamesis
• Kenya
• 3.9-4.2 mya
• Small hominin
• Teeth like A. afarensis
• Long bones suggest bipedalism
• Homo from the neck down and head like
  Australopithecus
• https//www.msu.edu/heslipst/contents/ANP440/anam
  ensis.htm

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Gracile Australopithecines A afarensis

• Australopithecus afarensis
• 4-3 mya in East Africa
• Laetoli, Tanzania
• Teeth and jaws
• Footprints3.6 mya
• Hadar, Ethiopia
• Lucy40 of skeleton found
• Pelvis shows she was bipedal
• 3.2 mya in semi-arid savanna

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Gracile AustralopithecinesA afarensis

• Australopithecus afarensis differs from A
  africanus in terms of date (earlier) and location
  (E Africa)
• Incisors and canines large and tooth rows
  converge
• Often has sagittal crest and temporo-nuchal crest
• Largest males were 150 cm tall and cranial
  capacity was about 415 cc
• (http//anthropology.si.edu/humanorigins/ha/afar.h
  tml and (https//www.msu.edu/heslipst/contents/AN
  P440/afarensis.htm)

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Gracile AustralopithecinesA africanus

• Rounded brain case, well-develop forehead and
  moderate brow ridges, projecting face
• Cranial capacity between 428cc and 485cc
• Adults 105-135 cm tall
• Chinless jaw of Miocene apes but broad incisors
  and short canines as well a relatively small
  molarsdental function similar to humans
• Broad pelvis, lumbar curve and hip joint and
  femoral bone analysis suggest bipedalism
• 3-2 mya so more recent than A afarensis

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Gracile AustralopithecinesA africanus

• The Taung Child A africanus
• Discovered in 1925 by Raymond Dart
• Child less than 3 years old
• Dates to about 3.2 mya
• Foramen magnum position and short incisors and
  canines were human-like rather than ape like
• Biped
• Mrs.Ples found in 1940s confirmed the discovery
  of A africanus as a biped
• (http//anthropology.si.edu/humanorigins/ha/afri.h
  tmlhomo and https//www.msu.edu/heslipst/content
  s/ANP440/africanus.htm)

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Robust Australopithecines

• Date between 2.5 mya and 1 mya in East Africa and
  South Africa
• A boisei (http//anthropology.si.edu/humanorigins/
  ha/bos.html)
• East African
• 2.3-1.3 mya
• A robustus (http//anthropology.si.edu/humanorigin
  s/ha/rob.htm)
• South African
• 1.8-1 mya
• Should they all be called Paranthropus rather
  than Australopithecus?

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Robust Australopithecines

• In comparison to gracile australopithecines they
  had
• Thick jaws
• Large molars and premolars
• Small incisors
• Massive muscle attachments for chewing
• Large sagittal crests for chewing
• A boisei more extreme than A robustus in these
  features
• Cranial capacity of both species of robust
  australopithecine was 490-530cclarger than
  gracile forms
• Body size similar to A africanus so relative
  brain size was larger than A africanus

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Robust AustralopithecinesA robustus

• Discovered in South Africa in 1938 when it was
  given the name Paranthropus in contrast to A
  africanus
• Large teeth and jaw and flat face
• 1.8-1 mya
• A robustus ate vegetable foods but new studies do
  not rule out other foods
• Not ancestral to Homo species
• (http//anthropology.si.edu/humanorigins/ha/rob.ht
  m)
• (https//www.msu.edu/heslipst/contents/ANP440/ro
  bustus.htm)

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Robust AustralopithecinesA boisei

• Mary Leakey and Louis Leakey discovered A boisei
  at Olduvai Gorge in 1959
• Leakey called the new fossil Zinjantropus
• Now placed in the Australopithecines
• Extremely robust facial features
• Molar teeth, expanded premolars, massive and
  thick jaw, large sagittal crest
  (http//anthropology.si.edu/humanorigins/ha/bos.ht
  ml) and (https//www.msu.edu/heslipst/contents/AN
  P440/boisei.htm)
• 2.3-1.3 mya in dry, open environment
• Questions about robust Australopithecines
• Some lived at same time as Homodid they make and
  use tools found after 2.5 mya?
• Are similarities in robust forms (ie A robustus,
  A boisei and later H erectus due to evolutionary
  convergence or ancestral linkages?

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Stone tools and hunks of rock

• Provenience
• Kind of rockcan be flaked and will lastflakable
  and durable
• Bilateral flakingboth sides of stone struck to
  make and cutting edge
• Retouching
• Striking platform

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Lines of Descent

• See page 180 of the text and http//anthropology.s
  i.edu/humanorigins/ha/a_tree.html
• Between 3 and 1 mya there were at least two
  hominin lines
• Robust australopithecines became extinct about 1
  mya and were not ancestral to modern humans
• Homo habilis was in direct lines of descent to H
  sapiens

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Themes

• Complex jig-saw puzzle with pieces spread over
  100s of miles and millions of years
• Lots of ego involved in this work!
• Various species of Australopithecus existed
  together and in sequence
• A afarensis most likely ancestor of Homo
• Bipedal but not yet making toolsalso possibly
  partially arboreal in some species
• Sexual dimorphism especially in the robust forms
• Increase in cranial capacity indicating larger
  brains over time