9/6/16- Hominin Origins and Evolutions: Part 1Evidence for the biological evolution of humans consists of fossilized bone, genetic histories, and other data9/6/16- Hominin Origins and Evolutions: Part 1- Evidence for the biological evolution of humans consists of fossilized bone, genetic histories, and other data- Geological contexts of fossils and genetics data agree that the last common ancestry between chimpanzees and modern humans existed between 5-8 million years ago- Any species considered more closely related to humans than chimps we call hominims - Anthropoid and Hominid Beginningso First mammals appeared ca. 200 myao First primate-like mammals appeared ca. 65 mya, when dinosaurs went extinct and climate grew coolerso Ancestors of monkeys, apes, and humans (the Anthropoids) branched off from a prosimian-ancestral line ca. 50 myao First ape-like primates (the hominids) appear ca. 23 mya, at the beginning of the Mioceneo Cladogenesis Tree diagram Meaning a branching-off- MIOCENE APESo Miocene (23-5 mya) is the “age of the apes”o Adaptive radiation involving populations in Africa, Europe, and Asiao Nearly 30 genera recognized, many with no living descendantso Shift in Earth’s plates helps account for radiation out of Africao At 16 mya, Africa “docked” into Eurasia, enabling crossoverso Climate was becoming drier, opening up African forestso Proconsul, genus of African Miocene hominids with mixture of old world monkey traits and ape traits- The African Ape-Hominin Split: Bipedalismo Humans and their hominin ancestors are distinct from hominoidsfor BIPEDALISM: locomotion on two feeto For a hominoid fossil to be classified as a hominin, it has to have evidence for bipedalismo Suggestive fossil evidence for bipedalism dates as early as 7 mya;sound evidence dates to ca. 4.2 myao The fossil evidence finds support in molecular data, which puts African ape-hominin split at ca. 7-5 mya- Anatomy for Bipedalismo Foot Arch Great toe aligns with otherso Pelvis Basin shaped Legs to side Leg sockets angled inwardo Legs Femurs angled inward Offset facets at knee Knees lock in extended positiono Spine S-shaped, lumbar curveo Skull Foramen magnum faces downwardo Human foot has arch and great toe aligned with otherso Propulsion in humans from heel, along outside of arch, across to ball of foot, then out through great too Human hips are short and basin-shaped, with leg sockets angled inwardo Humans knee offsets angle in knee to give us a straight down angleo Even the human skull shows anatomy for bipedalism: straight downward orientation of FORAMEN MAGNUM (i.e. opening of spinal cord and other vital parts) on skull of