ATH 351-02

Human evolution (basal hominins)

full articulated skeletons v. rare

all species combinations of primitive, derived, etc traits

African origin (Lake Chad 7mya, Rift Valley 4mya, S.Afr. 3mya)

river habitation @ rift vall.

Dating in Paleoanthro:

  • biochronology (diagnostic/index fossil succession)
  • Stratigraphy
  • paleomagnetism (current: Brunhes normal chronology)
  • dating methods:
    • relative
    • chronometric

Chronometric methods

Sahelanthropus tchadensis (Toumai)

  • context
    • Lake Chad 7mya
    • woodland habitat
  • discoverer
      • Michel Brunet – 2002
  • derived traits
    • Foramen Magnum central
    • Cranium small, non-Canine/Premolar honing complex
    • reduced prognathism (facial projection)
  • primitive traits
    • small brain (320cc)
    • large Supra-Orbital Torai

orrorin tugenensis

  • context
    • Kenya 6mya
    • forest habitat
  • dicoverers
    • Pickford & Senut 2000
  • Derived traits
    • femur w/thickened neck
    • obturator groove
    • thick molar enamel
  • primitive traits
    • long femoral neck, small head
    • large I&C, small M

ardipithecus kadabba

  • context
    • Ethiopia – 5.5-5.8 mya
    • woodland habitat
  • discoverer
    • Haile-Selassie – 2001
  • derived traits
    • foot bones indicate bipedality
  • primitive traits
    • C/P honing retained

ardipithecus remidus

  • context
    • Ethiopia 4.4mya
    • woodland fauna
  • discoverer
    • Tim White 1994
  • derived traits
    • smaller upper C than apes
    • anterior FM
  • primitive traits
    • thin dental enamel
    • retained C/P honing complex
    • narrow molars

Above: potential hominin — Below: definite hominin

australopithecus anamensis

  • context
    • Kenya, Kanapoi, Allia Bay
    • Ethiopia, Afar
    • 4.2mya
    • dry, open woodland
  • discoverer
    • Meave Leakey 1995
  • derived traits
    • equal tibial condyles
    • wide proximal tibia
  • primitive traits
    • large C, parallel tooth rows

Why bipedalism?

  • free upper limbs for carrying
    • carry tools, infants
    • food provisioning (Lovejoy)
  • reach fruit in small trees
  • see over greater distances
    • predator avoidance
  • reduce heat sress (Wheeler)
  • cover ground between trees
  • increased energy efficiency (Rodman & McHenry)

Piltdown hoax (“Eoanthropus dawsonii”)

  • Darwin’s scenario
    • bipedality, encephalization, culture, language
  • Piltdown 1912 in England
    • fraud determined in 1953
    • FUN dating (fluorine, uranium, nitrogen)
    • human skull & orang mandible
  • eurocentrism
    • colonialism, imperialism
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