Identify traits that distinguish primates from other mammals.

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Primates and Human Origins

• Identify traits that distinguish primates from
  other mammals.
• Describe fossil evidence relating humans to
  primate ancestors.
• Compare hypotheses concerning hominid evolution.

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Primates and Human Origins

• Characteristics
• Many primate characteristics are generalized
  rather than specialized and are similar to
  features possessed by ancestral mammals.
• Many primate traits are adaptations for living in
  groups in trees.
• Examples include strong three-dimensional vision
  and prehensile appendages, or hands, feet, and
  tails that can grasp.
• The primate brain, with its large cerebrum, is
  able to interpret complex visual information and
  keep track of subtle shifts in social
  organization.

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Primates and Human Origins

• Primate characteristics include
• Large brain parts relative to size
• Acute color vision
• Generalist teeth
• Communication
• Infant care
• Manual dexterity
• Social organization
• Characteristic skeletal structure

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Primates and Human Origins

• Prosimians Anthropoids
• The primate lineages that evolved the earliest
  include lemurs, lorises, and tarsierssometimes
  referred to as prosimians.
• The anthropoid primates include gibbons, New
  World monkeys, Old World monkeys, and apes,
  including humans.
• Anthropoid adaptations include rotating shoulder
  and elbow joints and an opposable thumb.
• All anthropoids have a similar dental formula.
• Compared to other primates, anthropoids have a
  more complex brain structure and a larger brain
  relative to body size.
• Orangutans, gorillas, chimpanzees, bonobos, and
  humans make up the great apes.

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Primates and Human Origins

• Modern Humans
• Among living mammals, only humans, Homo sapiens,
  have the trait of bipedalism.
• The human skeleton is adapted for bipedalism in
  several ways. The bowl-shaped human pelvis
  supports internal organs.
• The human spine curves in an S shape.
• Human toes are aligned with each other and are
  short.
• The larger brain and smaller jaw in humans result
  in a flatter face than that found in apes.
• The human brain is capable of speech
  communication.

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Primates and Human Origins

• Hominids
• Hominids include humans and extinct humanlike
  anthropoid species.
• Bipedalism is the distinguishing characteristic
  of this group.
• Apelike ancestors of the first hominids were
  probably quadrupedal.
• Fossil evidence has provided some clues as to how
  long ago the first bipedal hominid evolved.

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Types of Primates
Primates and Human Origins
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Primates and Human Origins

• Fossil Hominids
• Paleontologists and anthropologists have
  concluded that a variety of humanlike species
  lived on Earth within the past 10 million years.

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Primates and Human Origins

• Australopithecines
• A number of fossils of bipedal anthropoid
  primates with the brain size of a chimpanzee have
  been discovered in parts of Africa and date from
  about 2.5 million to 4 million years ago.
• These organisms have been classified in the genus
  Australopithecus within the subfamily of
  australopithecines, which may include other
  genera.
• The first australopithecine fossil discovery,
  nicknamed Lucy, was found in 1974 in the Afar
  Valley region of Africa by Donald Johanson and
  colleagues.

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Primates and Human Origins
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Comparing Gorillas and Australopithecine Skeletons
Primates and Human Origins
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Primates and Human Origins

• Paleontologists continue to find new hominid
  fossils and debate their classification.
• It is clear that several hominid forms arose,
  thrived, and became extinct over the past 7
  million years. Different species may have
  coexisted in time and possibly interacted.

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Primates and Human Origins

• Early hominid species include
• Gracile (slender) australopithecines
• Australopithecus afarensis (Lucys species)
• A. anamensis
• A. africanus
• Robust australopithecines (may be genus
  Paranthropus)
• A. aethiopicus
• A. robustus
• A. boisei

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Primates and Human Origins

• Sometime after australopithecines, the genus Homo
  appeared.
• Extinct and living members of this genus are
  called humans.
• Homo habilis and Homo erectus
• Homo habilis means the handy human.
• A later species was Homo erectus (meaning
  upright human).

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Primates and Human Origins

• Homo sapiens and Homo neanderthalensis
• Neanderthals, now classified as H.
  neanderthalensis, lived in Europe and Asia from
  about 230,000 to 30,000 years ago.
• They may have interacted with H. sapiens in some
  places.
• The first humans classified as H. sapiens
  appeared about 160,000 years ago.
• Some early fossils of H. sapiens are referred to
  as Cro-Magnons.

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Primates and Human Origins

• Modern Humans
• Two major hypotheses have been proposed to
  explain how modern humans come to occupy the
  entire globe
• In the multiregional hypothesis, local
  populations of H. erectus gave rise to local
  populations of H. sapiens all over the world.
• In the recent-African-origin hypothesis, H.
  sapiens evolved from H. erectus in Africa, then
  migrated out of Africa and populated the globe.
• An analysis of mitochondrial DNA from people
  around the world suggests that humans did arise
  in Africa.

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Primates and Human Origins
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Early Members of the Human Genus
Primates and Human Origins
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