Hominid Evolution

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Hominid Evolution

• Physical changes in hominid characteristics and
  behavior over time.

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Homo Sapiens Sapiens (modern man, present day)
http//www.bio.miami.edu/dana/pix/human_skull.jpg
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Homo Sapiens sapien (modern man, older, found in
czech republic)
http//www.bio.miami.edu/dana/pix/human_skull.jpg
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Homo Sapiens sapien (modern man, cro-magnon,
oldest found in France)
http//en.wikipedia.org/wiki/FileCro-Magnon.jpg
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Homo sapiens rhodesiensis
http//en.wikipedia.org/wiki/FileBroken_Hill_Skul
l_(Replica01).jpg
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Homo Sapiens neanderthalensis (Neandertal)
http//en.wikipedia.org/wiki/FileHomo_sapiens_nea
nderthalensis.jpg
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Homo erectus pekinensis (peking man)
http//en.wikipedia.org/wiki/FilePeking_Man_Skull
_(replica)_presented_at_Paleozoological_Museum_of_
China.jpg
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Homo erectus modjokertensis
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Paranthropus (Australopithicus) boisei
http//en.wikipedia.org/wiki/FileAustralopithecus
_boisei_P1060081.jpg
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Homo habilis (handy man)
http//en.wikipedia.org/wiki/FileHomo_habilis-KNM
_ER_1813.jpg
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Australopithicus africanus (taung child, Mrs.
Ples)
http//en.wikipedia.org/wiki/FileTaung27s_child.
jpg
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Sustralopithecus (Australopithicus) afarensis
(lucy)
http//www.skullsunlimited.com/graphics/bh-021t-lg
.jpg
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Pan Troglodytes (Chimpanzee)
http//www.boneclones.com/BC-003.htm
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Gorilla Gorilla (Gorilla)
http//www.sideshowtoy.com/?page_id4489skuBC001
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General Trends in Hominid Evolution - Braincase

• Smallest to largest chimp, homo habilis,
  gorilla, a. africanus, S. afarensis, H erectus,
  neandertal, H.S. rhodesiensis, H. S. sapiens
  (cro-magnon to modern)
• As hominids evolved, the braincase, in general
  got larger.

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General Trends in Hominid Evolution Sagital
Crest

• Sagital crest was largest in the gorilla, chimp,
  A. boisei, and H. erectus. By the time modern
  man evolved the sagital crest had disappeared.
• The sagital crest anchors extremely large jaw
  muscles and is found in animals that eat very
  tough food such as branches, shrubs, tough
  leaves, nuts, barks etc.

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General Trends in Hominid Evolution - Prognathism

• In older species the prognathism sticks out
  farther, meaning a lesser angle. Chimp, gorilla,
  H. habilis, and S. afarensis show the smallest
  angle while H. sapiens sapiens has the steepest.
• The greater the angle of prognathism, the weaker
  the jaw of the organism. This indicates that the
  diet of hominids got softer as the species
  evolved.

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General Trends in Hominid Evolution other
features

• As species evolved, the foramen magnum moved from
  the back of the skull to the center. This
  indicates that the species went from walking on 4
  legs to two over time.
• As species evolved, the supraorbital ridge went
  from large to small. This structure provides
  reinforcement to the skull to account for the
  pressure of large jaw/facial muscles flexing.
• The similar number of teeth and dental formula
  indicate that all members that we looked at
  evolved from a common ancestor. The diet did not
  change very much over time.

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Big Conclusions

• Species that evolved at an earlier time had a
  harder diet than we do today. Older species ate
  nuts, bark, branches, and tough, woody stems.
  This is shown by larger sagital crest and
  supraorbital ridges, and lower prognathism angle.
  This indicates that early human ancestors lived
  in the forest and gradually migrated to open
  grasslands.

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Big Conclusions cont.

• This move from forest to savannah also favors a
  more upright posture. In an environment with
  tall grasses walking on 2 legs allows you to see
  over the grass and look out for predators.
• The large canines on the chimp and gorilla are
  not for eating meat but rather they are used for
  fighting and sexual selection. Large teeth are
  more attractive and indicate good genes.