Know Thyself Carolus Linnaeus Human Origins A Confluence

“Know Thyself” Carolus Linnaeus

Human Origins: A Confluence of Research Paleontology n Anthropology n Archaeology n Genetics n Paleoclimatology n

Conflict, Racism and Uncertainty n n 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 n n A) Very young discipline B) Relatively sparse fossil record

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

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

The Cradle of Humanity n n n 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

Famous locations of hominid fossils n Olduvai Gorge n Hadar n Laetoli

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

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

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

Australopithecus afarensis – “Lucy” n n n n 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

Australopithecus afarensis

Footprints at Laetoli, Tanzania (3. 6 Ma) – probable A. afarensis

Australopithecus afarensis and Homo habilus

One Version of the Time Line

General Picture of Hominid Evolution Probable common ancestor of humans and chimps circa 5. 5 Ma n Pliocene saw several hominid species coexising n Several lineages became extinct n Which one was our ancestor? n

Kenyanthropus platyops – an early ancestor to rival A. afarensis? n n n 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 –

General Picture of Hominid Evolution n n 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

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