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QUICK STUDY NOTES - How Humans Evolved - Chapter 10-13 - BIO 1M03

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James S Quinn

Chapter 10: From Tree Shrew To Ape Radiometric Dating 1. Potassium Argon Dating (500k years) – argon absent for lava – any argon in volcanic rock is derived from K decay 14 12 14 12 2. Carbon-14 Dating (~40k)– live animals C and C of atmosphere; after death, C decays into C – ratio to estimate age Radiometric Methods 1. Thermo luminescence Dating – high energy nuclear particles from cosmic rays and radioactive decay are trapped by particles that are released when heated; burning resets particle composition – measure particle composition to quantity age of burned material 2. Electron Spin Resonance Dating – determines age of apatite crystals; measures age according to presence of trapped e - Problems with Radiometric Dating  Particular site may not always contain appropriate material  Methods can have large confidence interval Radiometric Dating is often supplemented with relative methods 1. Magnetic Reversals 2. Extinct and Distinct Species of Animals Vascular Plants – circulation system; larger than non-vascular plants Gymnosperm – produces ovules that lack a cover Angiosperm – vascular plants that form flowers; seeds can have a fruit coat around seed coat (testa), must have endosperm within seeds  By end of Cretaceous 65 mya, large canopy forming angiosperms replaced conifers as dominant trees  Relationship with animals – pollination, defense, dispersal Primate  Adaptations for climbing and locomotion (leaping, walking etc.)  Opposable thumbs, prehensive tails  Stereoscopic vision  3-color vision (Some)  nails (instead of claws) on toes and fingers  5 digits Plesiadapiforms – extinct; some primate-like traits; 65-54 mya  Carpolestes simpsoni – small creature, lived ~56 mya, opposable big toe with flat nail instead of claws, molars consistent with frugivory Primate Traits Favored By Natural Selection 1. Binocular Vision 2. Grasping Hands and Feel 3. Nails on Fingers and Toes  Enhanced visually directed predation in insects in the terminal branches of trees  Facilitate locomotion (leaping)  Enhance the ability to exploit a new array of plant recourses on terminal branches of angiosperms Eocene Primates  Wetter and Warmer Climate  Ancestor of “wet nosed”, “flat nosed”, “downward nosed” primate lived  Features that define modern primates 1. Grasping hands and feet with nails instead of claws 2. Hind limb-dominated posture 3. Shorter snouts 4. Eyes moved forward in the head and encased in a bony orbit 5. Relatively large brains  Two Families 1. Adapids - small eye orbits, probably diurnal, variable diet adaptations, similar to lemurs 2. Omomyidae – large eye orbits probably nocturnal, similar to galagos and tarsiers First Anthropoids Oligocene Primates  Cooler Climate  Prosimians (wet nosed), anthropoids (flat nosed) and “downward nosed” primates  Monkeys reached SA by late Oligocene – evolved into “flat nosed” primates = NWM  By late Oligocene, SA and Africa were separated by ~3000km  No fossils of anthropoids in NA, only prosimians – anthropoid primates dispersed earlier when South Atlantic Ocean was more narrow Miocene Primates  Climate initially warmer – became cooler and more arid  Apes diversified but eventually all ancestors of extant lineages went extinct by end of Miocene  Monkeys diversified extensively in Late Miocene, early Pliocene Teeth  Informative; complex structures that reflect dietary specialization  Tooth enamel not remodeled during animals life  Preserves better than bones Hominoids and Apes – refers to clade that includes 1. Gibbons 2. Orangutans 3. Gorillas 4. Chimpanzees 5. Humans  Apes differ from monkeys in some dental and skeletal traits, brain size and life history patterns o Apes – suspensory posture o Monkeys – climb on top of branches Origins of Violence  Gibbons – monogamous  Orangutans - solitary, bi-maturation, occasional forced copulation  Gorillas – harems, one silver back male with many females with offspring; infanticide  Chimps – multi-male, multi-female groups, male dominated hierarchy, raids  Bonobos – less hierarchal, strong female-female bonds, same-sex sex Adaptations for Suspensory Locomotion 1. Short trunk and legs 2. Long arms and fingers 3. Fingernails instead of claws 4. Inward closing hook-like fingers 5. Opposable thumbs 6. Shoulder, wrists and other joints more mobile Chapter 11: From Hominoid to Hominin Late Miocene/Pliocene Primate’s  Global cooling associated with decreased rainfall and seasonality, including dry seasons  5 Human Characteristics 1. Bipedalism 2. Differences in dental anatomy from other apes 3. Very large brains relative to body size 4. Long period of juvenile development 5. Language – spoken and dependent on a material and symbolic culture Chimp-Human Split (5-7mya) 1. Aridipithecus ramidus 2. Orrorin tugenensis 3. Sahelanthropus tchadensis  Features of fossils: o Small molars o Thin enamel o Canines larger than humans o Large brow ridge o Small brain case relative to hu
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