4/8 Biological Anthropology- Paleoanthropologyo Explore evidence for human evolutiono Begin w/ a consideration we determine the age of fossils o Keyanthropus platyops-human ancestor? North Kenya Very distorted and is therefore contradictory- Late Cretaceous 90 MYA- Chronology and dating fossilso Relative dating techniques date one event relative to anothero Law of stratigraphic succession; layer of earth are older when lower insequenceo Biostratigraphy  Using index fossils to relatively date the rocks in which fossils are found Index fossils have short timespan and great range Can correlate w/ other fossils Allow correlation from undated to well dated sites- Absolute dating; exponential decay process (radiometric uses this)o Yields ages in years BPo Half life is time for the half of radioactive material decaying from a parent to a daughter isotopeo Carbon 14->Nitrogen 14o Potassium 40->Argon 40o Carbon 14 datingo Useful only up to 50,000 yao Carbon 14 produced in the atmosphere and it enters into the food chain, C14 and C12 in the atmosphere and in organisms is at an equilibriumo C14 decays to N14 and Ca14 and changing ration of C14 to C12 and this gives specimens ageo ½ life of C14, 5,730 years for ½ of C14 will be lost and only half will remain- Potassium Argon datingo 1/2 life of 1.3 BYA o used to date moon rocks – 4 BYAo K20 decays to Ar40 in volcanic rockso Calibration is reset by recent eruptions, in that material the Argon gas is released when rocks are heated to molten - Geologic time scales o 65-55.8 MYA Paleoceneo 59-34 MYA Eocene (primates)o 34-23 MYA Oligoceneo 23-5.3 MYA Miocene (age of apes)o 5.3-2.6 MYA Plioceneo 2.6-0 MYA Pleistocene (ice age)o 0-10KYA Holocene- Deep timeo Generational timeo For humans 20 year generational span 5 generations every 100 years 50 generations every 1,000 years 50,000 generations over 1 MYA 250,000 generations over 5MYA- KT boundaring-geological signature that divides the Mesozoic to the Cenozoic- Age of Apes (Miocene)o Europe, Asia and Africao Proconsul-ape b/c it has no tail Early ape Wide frontal, wide incisors Basil Catarrhine, monkey and ape like Not a brachiator, quadroped- Afropithecus- Griphopithecuso Curved shaped face of apes- Late Miocene apes-Sivapithecus indicus, o Indian continent, Siwalik Hills, Pakistan 12.5-8.5 MYAo Ancestor of orangs?o During Middle Miocene many ape specieso Ape species decline in Late Mioceneo Cooling trendo Forest reductiono Increase in Old World Monkey species (beginning to out compete apes)o Apes show up earlier than monkeyso Some terrestrial, arboreal, quadropedal, suspensory hanging- Early Homininso Africa, Late Miocene 7 MYAo Anatomical traits indicating use of bipedalityo Upper body characteristics for suspensory locomotiono Brain size to body size ratios comparable to modern chimps and bonobos, small, as intelligent as those species; large brains and complex behavior (1000-2000cc)o Language, culture, stone toolso Reduced dentition especially canineso Upright posture and bipedal locomotion (anatomical changes in lowerlimb and spine)- Mosaic Evolutiono Different traits evolve at different times- Pre Genus HOMO homininso Bipedal apes- Hominin bipedalismo 6 anatomical features 1) placement of foramen magnum underneath the brain, head balance and movement of head 2) 2 types of vertebral curvature kyphosis-seen in chimps, bonobos, gorillas, thoracic curvature Lordosis-‘S’ shaped curve in lumbar and cervical regions; cervical 1st the lumbar 3) pelvis, shape and placement of iliac crests 4) Longer lower limbs 5)Foot changes-trade off btw mobility for stability in unipedally 6)Knee is angled in, unipedal stance, hip, knee, and foot in vertical line loose opposable big tow and no longer grasping(divergent) longer lower limbs carrying angle of femur pelvis-orientation of musculature- changes to iliac accompany bipedalism - gluteus helps our pelvis not get out from under us provides lateral stability during bipedalism all the configurations help us walk w/ our eye level at a smoothpath- 8 mm of movement at eye