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“Know Thyself”

“Know Thyself”. Carolus Linnaeus. Human Origins: A Confluence of Research. Paleontology Anthropology Archaeology Genetics Paleoclimatology. Conflict, Racism and Uncertainty. Human origins – commonly at center of the Evolution vs. Creation “debate”

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“Know Thyself”

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  1. “Know Thyself” Carolus Linnaeus

  2. Human Origins:A Confluence of Research • Paleontology • Anthropology • Archaeology • Genetics • Paleoclimatology

  3. Conflict, Racism and Uncertainty • Human origins – commonly at center of the Evolution vs. Creation “debate” • Evolution and human origins are investigated scientifically – hypotheses are proposed and tested • Creationism/Creation Science/Intelligent Design, etc. are faith, not science • Topic is full of uncertainty • A) Very young discipline • B) Relatively sparse fossil record

  4. A Family Dynasty – the Leakeys: Louis, Richard, Mary and Richard Jr. • Mary Leakey - A lifetime of contributions including: • Many “first discoveries” of skulls, etc. • First hominid footprints

  5. A Patchy Fossil Record • Upland habitat – erosion vs. deposition • Fossils are not abundant • Most important sites are in Tanzania, Kenya, Ethiopia (East African Rift System) and Egypt • Teeth predominate • Jaw and skull fragments • Taphonomic changes make taxonomy difficult • Rare post-cranial skeleton • Few complete or nearly complete skeletons • Footprints

  6. The Cradle of Humanity • The East African Rift System • Earthquakes and formation of rift as Africa splits • Sinking of rift floor promoted accumulation of sediments • Early hominids preserved in these sediments • Recent erosion cuts through sediments to reveal fossils

  7. Famous locationsof hominid fossils • Olduvai Gorge • Hadar • Laetoli

  8. Arboreal Ancestors? • Characteristics of tree dwellers • Flexibility and agility • Parallax vision – eyes in front of head • Vision predominates over sense of smell • Enlarged brain to handle visual data • Secondary adaptations to bipedality (from tree swingers)

  9. Of Apes and Man • Divergence in Early Cenozoic – Oligocene? • Apes and Hominids • More gap than record • Too early to establish evolutionary relationships among species • Discovery of each new species changes picture • So, what is a hominid?

  10. Characteristics of Hominids(a.k.a. hominins) • Arched palate • U – shaped jaw • Uniform dentition (no diastema) • Enlarged skull and brain case • Opposable thumb • Bipedal • Paralax vision

  11. Australopithecus afarensis – “Lucy” • Circa 3.8 Ma Pliocene to Pleistocene (?) • Female • Four feet tall • Less than 100 lbs. • Tool user, but not maker • Coexisted with A. robustus • Upright posture and bipedality arise before enlargement of braincase

  12. Australopithecus afarensis

  13. Footprints at Laetoli, Tanzania(3.6 Ma) – probable A. afarensis

  14. Australopithecus afarensis and Homo habilus

  15. One Version of the Time Line

  16. General Picture ofHominid Evolution • Probable common ancestor of humans and chimps circa 5.5 Ma • Pliocene saw several hominid species coexising • Several lineages became extinct • Which one was our ancestor?

  17. Kenyanthropus platyops –an early ancestor to rival A. afarensis? • Mid-Pliocene (circa 3.5 Ma) • Some similarities to Homo (Kenyanthropus) rudolfensis • Coeval with A. afarensis • More “modern” appearances millions of years earlier than previously thought • Possibly incorrect – taphonomic distortion?

  18. General Picture ofHominid Evolution • Genus Homo arises circa 2.0 Ma (H. habilus) - Pleistocene • H. habilus – a tool maker and user, fire, built shelters, social structure • H. sapiens arises circa 500,000 to 300,000 ybp (Late Pleistocene) • Modern Humans arise about 100,000 ybp

  19. The Hominid Time Line • Accurate dating of fossils is critical • Direct evolutionary relationships are still unclear • New fossil discoveries prompt revisions all the time • The burning questions: Who are we? What is our heritage? Where do we fit in the grand scheme of things?

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