Human%20Evolution

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Human Evolution
http//www.pbs.org/wgbh/evolution/library/07/1/l_0
71_01.html
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Topics covered in slide show

• Two theories on how evolution occurs
• Phylogeny and Cladograms
• Fossil Record and its gaps
• Human Evolution as determined from fossil record
• Are we still evolving?

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Types of Evolution

• Gradualism
• Punctuated Equilibrium
• Both play a role in evolution

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Gradualism

• Most evolutionary changes occur over long periods
  of time (when enviro. Is changing slowly)

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Punctuated Equilibrium

• Major evolutionary changes happen relatively
  rapidly and then are followed by a long period of
  very little change (occurs when species are
  exposed to new or rapidly changing enviro.)

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Phylogeny and Cladograms

• Phylogeny -Evolutionary relationship between
  organisms
• Cladograms -Diagram showing the evolutionary
  relationship of different groups of species

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Cladogram
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Evolution of Hominid Species
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Fossil Record and its Gaps

• In evolution, one of the key sources of evidence
  in fossils
• There are gaps in fossil record
• Gaps dont undermine all the other evidence of
  evolution
• Scientific investigations are continually filling
  these gaps

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Human Evolution as determined from fossil record

• There is a rich fossil record of human ancestors
• Homo sapiens first evolved in Africa and began
  spreading our from Africa 50 000 years ago
• Key evolutionary characteristics of humans
• Bipedalism
• Large brain
• Fine manipulation with hands

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Migration of Early Hominids
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Continued

• Humans closest related living species is the
  chimpanzee (closest relative)

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Are we still evolving?

• Rate of human evolution has been greater over the
  past several thousand years than during the past
  few million years
• Eg. Evolution of lactose tolerance
• Evolution of infectious diseases (HIV) and
  humans evolutionary responses are being studied
• Artificial selection of plants and animals has
  caused human population to explode

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Continued

• Understanding our evolutionary past has many
  benefits
• In the past, taste for sweets and fats were
  beneficial
• Darwinian medicine (use of evolutionary theory to
  understand medicine) is insightful into cause and
  spread of disease

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Continued

• We have evolved a brain capable of knowing how to
  obtain a sustainable future
• We have the tools and freedom to direct our
  unknown evolutionary future

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Reference

• Biology 11 Nelson 2011

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Questions

• Did we evolve from the chimpanzee? Justify your
  answer
• Trace the migration of homo sapiens.
• Does Cultural evolution affect biological
  evolution? Justify your answer.