BSC2010-evolution-10-2023.ppt

Human Evolution BSC2010,Fall 2023 Outline 1. Humans in the tree of life 2. The evolution of primates 3. The evolution of H. sapiens • selective forces • phenotypic changes • geography Scientific American, 2014 Evolutionary Tree PLANTS flowering plants conifers ginkgos horsetails ferns FUNGI...

Human Evolution BSC2010,Fall 2023 Outline 1. Humans in the tree of life 2. The evolution of primates 3. The evolution of H. sapiens • selective forces • phenotypic changes • geography Scientific American, 2014 Evolutionary Tree PLANTS flowering plants conifers ginkgos horsetails ferns FUNGI sac club fungi fungi cycads zygosporeforming fungi lycophytes ANIMALS arthropods chordates annelids roundechinomollusks worms derms rotifers flatworms cnidarians bryophytes chlorophytes (stramenopiles) brown algae chrysophytes oomycotes sponges chytrids green algae amoeboid protozoans red algae slime molds ? crown of eukaryotes (rapid divergences) PROTISTANS ciliates (alveolates) sporozoans dinoflagellates euglenoids kinetoplastids parabasalids (e.g., Trichomonas) ARCHAEBACTERIA diplomonads extreme (e.g., Giardia) Gram-positive bacteria halophiles methanogens cyanobacteria extreme thermophiles molecular origin of life EUBACTERIA spirochetes chlamydias proteobacteria Mammals Chordates Birds Echinoderms “Reptiles” Amniotes Amphibians Arthropods Annelids Coelomate Ancestry Tetrapods Lungfishes Mollusks Lobe-finned Fishes Ray-finned Fishes Rotifers Roundworms Bilateral Ancestry Radial Ancestry Flatworms Cartilaginous Fishes Jawed Vertebrates Lampreys Vertebrates Craniates Cnidarians Hagfishes Cephalochordates Urochordates Multicelled Ancestry Sponges Single-celled, protist-like ancestors Chordates Our Phylum What features do these organisms share with other chordates? notochord, dorsal hollow nerve chord, gill slits, post-anal ta Urochordate Cephalochordate When did they first appear in the fossil record? > 500 MYA Characteristics of mammals? When did mammals arise? > 175 MYA Adaptive Radiation of Primates (65 MYA) Primates evolved from an ancestral arboreal insectivore about 65 mya • • • • • Great Apes—hominoids (25 MYA) Gorillas Orangutans Gibbons Humans Chimpanzees Changes in the Environment Warm, wet 23-5 mya—the Miocene Cool, dry Hominids split from other great apes about 5 MYA Common Misconceptions • Our ancestors were not chimps, or any other modern ape • Human evolution has not been ladder-like. Many evolutionary dead ends. Species of humans coexisted. From Ethiopia, in 2009…. Ardipithecus ramidus: 4.5 “Lucy”: Australopithecus afarensis 3.2 MYA Homo habilis in East Africa, 2.3-1.3 MYA Homo sapiens • Modern humans evolved by about 200,000 years ago • Compared to Homo erectus: – Smaller teeth and jaws – Smaller facial bones – Larger-volume brain case – Ability for symbolic thought Phenotypic Changes in Human Evolution • Mouth/dentition • Brain size • Bipedalism Bipedalism Laetoli footprints, 3.7 MYA Why bipedalism? Cultural Evolution: How does it intersect with biological evolution? Dates to know from this lecture for the exam • • • • • Adaptive radiation of mammals When mammals arose When great apes (hominoids) arose When hominids arose When Homo sapiens arose