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Human Origins:Human Origins:A Confluence of ResearchA Confluence of Research
PaleontologyPaleontology AnthropologyAnthropology ArchaeologyArchaeology GeneticsGenetics PaleoclimatologyPaleoclimatology
Conflict, Racism and Conflict, Racism and UncertaintyUncertainty
Human origins – commonly at center of Human origins – commonly at center of the Evolution vs. Creation “debate”the Evolution vs. Creation “debate”
Evolution and human origins are Evolution and human origins are investigated scientifically – hypotheses investigated scientifically – hypotheses are proposed and testedare proposed and tested
Creationism/Creation Science/Intelligent Creationism/Creation Science/Intelligent Design, etc. are faith, not scienceDesign, etc. are faith, not science
Topic is full of uncertainty Topic is full of uncertainty A) Very young disciplineA) Very young discipline B) Relatively sparse fossil recordB) Relatively sparse fossil record
A Family Dynasty – the A Family Dynasty – the Leakeys: Louis, Richard, Leakeys: Louis, Richard,
Mary and Richard Jr.Mary and Richard Jr.
Mary Leakey - A Mary Leakey - A lifetime of lifetime of contributions contributions including:including: Many “first Many “first
discoveries” of discoveries” of skulls, etc.skulls, etc.
First hominid First hominid footprintsfootprints
A Patchy Fossil RecordA Patchy Fossil Record Upland habitat – erosion vs. depositionUpland habitat – erosion vs. deposition Fossils are not abundantFossils are not abundant Most important sites are in Tanzania, Most important sites are in Tanzania,
Kenya, Ethiopia (East African Rift Kenya, Ethiopia (East African Rift System) and EgyptSystem) and Egypt
Teeth predominateTeeth predominate Jaw and skull fragmentsJaw and skull fragments
Taphonomic changes make taxonomy difficultTaphonomic changes make taxonomy difficult Rare post-cranial skeletonRare post-cranial skeleton Few complete or nearly complete Few complete or nearly complete
skeletonsskeletons FootprintsFootprints
The Cradle of HumanityThe Cradle of Humanity The East African Rift The East African Rift
SystemSystem Earthquakes and Earthquakes and
formation of rift as formation of rift as Africa splitsAfrica splits
Sinking of rift floor Sinking of rift floor promoted accumulation promoted accumulation of sedimentsof sediments
Early hominids Early hominids preserved in these preserved in these sedimentssediments
Recent erosion cuts Recent erosion cuts through sediments to through sediments to reveal fossilsreveal fossils
Famous locationsFamous locationsof hominid fossilsof hominid fossils
Olduvai Olduvai GorgeGorge
HadarHadar LaetoliLaetoli
Arboreal Ancestors?Arboreal Ancestors?
Characteristics of tree dwellersCharacteristics of tree dwellers Flexibility and agilityFlexibility and agility Parallax vision – eyes in front of headParallax vision – eyes in front of head Vision predominates over sense of Vision predominates over sense of
smellsmell Enlarged brain to handle visual dataEnlarged brain to handle visual data Secondary adaptations to bipedality Secondary adaptations to bipedality
(from tree swingers)(from tree swingers)
Of Apes and ManOf Apes and Man
Divergence in Early Cenozoic – Divergence in Early Cenozoic – Oligocene?Oligocene?
Apes and HominidsApes and Hominids More gap than recordMore gap than record Too early to establish evolutionary Too early to establish evolutionary
relationships among speciesrelationships among species Discovery of each new species changes Discovery of each new species changes
picturepicture So, what is a hominid?So, what is a hominid?
Characteristics of HominidsCharacteristics of Hominids(a.k.a. hominins)(a.k.a. hominins)
Arched palateArched palate U – shaped jawU – shaped jaw Uniform dentition (no diastema)Uniform dentition (no diastema) Enlarged skull and brain caseEnlarged skull and brain case Opposable thumbOpposable thumb BipedalBipedal Paralax visionParalax vision
Australopithecus afarensisAustralopithecus afarensis – – “Lucy”“Lucy”
Circa 3.8 Ma Pliocene to Circa 3.8 Ma Pliocene to Pleistocene (?)Pleistocene (?)
FemaleFemale Four feet tall Four feet tall Less than 100 lbs.Less than 100 lbs. Tool user, but not makerTool user, but not maker Coexisted with Coexisted with A. A.
robustusrobustus Upright posture and Upright posture and
bipedality arise before bipedality arise before enlargement of enlargement of braincasebraincase
Footprints at Laetoli, Footprints at Laetoli, TanzaniaTanzania
(3.6 Ma) – probable (3.6 Ma) – probable A. A. afarensisafarensis
General Picture ofGeneral Picture ofHominid EvolutionHominid Evolution
Probable common ancestor of Probable common ancestor of humans and chimps circa 5.5 Mahumans and chimps circa 5.5 Ma
Pliocene saw several hominid Pliocene saw several hominid species coexisingspecies coexising
Several lineages became extinctSeveral lineages became extinct Which one was our ancestor?Which one was our ancestor?
Kenyanthropus platyops –Kenyanthropus platyops –an early ancestor to rivalan early ancestor to rival A. A.
afarensisafarensis?? Mid-Pliocene (circa 3.5 Mid-Pliocene (circa 3.5
Ma)Ma) Some similarities to Some similarities to
Homo (Kenyanthropus) Homo (Kenyanthropus) rudolfensisrudolfensis
Coeval with Coeval with A. afarensisA. afarensis More “modern” More “modern”
appearances millions of appearances millions of years earlier than years earlier than previously thoughtpreviously thought
Possibly incorrect – Possibly incorrect – taphonomic distortion?taphonomic distortion?
General Picture ofGeneral Picture ofHominid EvolutionHominid Evolution
Genus Genus HomoHomo arises arises circa 2.0 Ma (circa 2.0 Ma (H. H. habilushabilus) - Pleistocene) - Pleistocene
H. habilus H. habilus – a tool – a tool maker and user, fire, maker and user, fire, built shelters, social built shelters, social structurestructure
H. sapiensH. sapiens arises arises circa 500,000 to circa 500,000 to 300,000 ybp (Late 300,000 ybp (Late Pleistocene)Pleistocene)
Modern Humans Modern Humans arise about 100,000 arise about 100,000 ybpybp
The Hominid Time LineThe Hominid Time Line
Accurate dating of fossils is criticalAccurate dating of fossils is critical Direct evolutionary relationships are Direct evolutionary relationships are
still unclearstill unclear New fossil discoveries prompt New fossil discoveries prompt
revisions all the timerevisions all the time The burning questions: Who are we? The burning questions: Who are we?
What is our heritage? Where do we What is our heritage? Where do we fit in the grand scheme of things?fit in the grand scheme of things?