ANTHROPOLOGY 3300 EXAM 1 STUDY GUIDE WHAT IS HUMAN EVOLUTION What questions could be asked about a skull Morphological questions Contextual questions o Context is as important as the fossil itself Major Trends in Hominin Evolution Bipedalism Brain expansion and elaboration o Brain size vs body size Increased body size Facial reduction Culture Ecological adaptability FOSSILS AND FOSSILIZATION Fossilization a process The replacement of organic material with inorganic material Can take thousands of years Isn t always great or complete Taphonomy The study of the processes that occur after death including the process of fossilization Taphos grave Ex Taung South Africa actual site in Buxton edge of Kalahari desert o 1924 limestone quarry o Hit large pockets of red sandstone Where fossils were found o Fossils brought to Raymond Dart University of Witwatersand Johannesburg Professor of Anatomy specialize in the brain Identified a fossil as endocast Fossil of a brain Foramen Magnum under not behind Bipedal animal Found full skull Child 3 4 yrs Australopithecus africanus Taung Child Breccia Broken Rock o Found a skull front Dolomite ancient limestone porus Tufa forms caves that can be dug thru o Given a dead baboon o Put it in Tufa cave o Taphanomic experiment 4 years 25 bones left over millions of years larger brain body size Lipriani Photo 1927 o egg shell genie fowl o jaw Taphonomy cont Parapapio broomi Reconstructing the community of the fossils Don t get all of the community fossils o Only the death assemblage o From the assemblage only some things get deposited o Only few fossils Community Death Assemblage Deposition Fossilization excavation publication EVOLUTIONARY THEORY AND THE SCIENTIFIC METHOD Evolutionary Theory and the Scientific Method Must propose testable hypothesis o EX Some unicorns are purple not testable o Ex All unicorns are purple testable Can be disproven The Killer Ape Hypothesis by Raymond Dart Robert Ardrey A africanus o Hypothesis Early hominins were violent brutal o Sub hypothesis early hominins use bones as tools o Sub sub hypothesis Hominin bone tool use is the only explanation for the fossil bone assemblage o Explanation o Evidence DISPROVEN Hyenas chew and break bones to look like tools Darwin s Prescient Insight Context is as important as the fossil o Human ancestors originated in Africa Hypothesis Evidence o Taung child o NOT disproven DATING METHODS IN PALEOANTHROPOLOGY For constructing evolutionary sequences and correlating event across Dating in Context continents and the globe 1820 Historical geologists looked for evidence of the biblical flood Charles Lyell o Found a lot of fossils o Couldn t all be from on event flood o Uniformitarianism All geologic phenomena are the result of existing forces having operated uniformly from the origin of the earth to the present Implied great antiquity of Earth Overcame a great impediment to scientific though the age of the earth Long term Evolution Earth is 4 5 billion years old Absolute dating Specific age in year BP before present Examples of absolute dating o Carbon Dating 200 50 000 years ago 14C radioactive isotope decays into non radioactive isotopes 12C and 13C 14C has a half life of 5 730 40 years proportion 12C to 14C increases with time o Potassium argon dating Used on volcanic tuff in eastern Africa 40K 40Ar or 40Ar 39Ar Half life of 1 3 billion years o Uranium series dating 238U or 235U daughter isotopes Used on tufa speleothems and apatite Half life of 4 47 years Problem with diagenesis mineral replacement Old rock is being replaced with newer rock limestone o Paleomagnetism Shifts in earth s magnetic poles Reversal North becomes South South becomes North Take place at slightly irregular intervals o Electron Spin Resonance Detects presence of unstable electrons trapped in solids Useful for sites around 100 000 to 2000 000 years Larger margin of error at older sites Relative Dating Examples of Relative Dating o Superposition Older things are on the bottom and newer things are closer to the top Formations Members and Beds Members Beds Units of formations Units of members o Faunal Dating Guild fossils and faunal seriations Faunal seriations Compare similarities among presence of species in faunal assemblages FADs and LADs vs Origins and Extinctions FAD LAD First appearance dates o Select against left and for right the extremes o The average of the population would change in a specific Last appearance dates SOURCES OF GENETIC VARIATION The Four Forces of Evolution Natural Selection Directional Selection direction Stabilizing Selection o Select against the extremes o Select for the average o Ex 4 chambered heart Disruptive Selection o Select for extremes o Select against the average Mutation The ultimate source of genetic variation Mutation rate number of mutations per gene location per generation Average known mutation rate 10 6 1 in a million Best estimate 10 5 1 in 100 000 Most mutations have no effect Genetic Drift Sewall Wright Sampling error in small populations Chance driven directional effect leading to loss of fixation of alleles Two kinds o Founders Effect Bottlenecking in population Variations get bottlenecked then change over time from the original population o Fixation Cross generational sampling error Allele frequencies change One allele takes over and become the only one fixation Other allele is lost Gene Flow Hybridization Interbreeding Increases the amount of variation Peopling the New World Facial Features o Mongoloid wash Asian proportions and features Decreases north south Blood type o Native Americans 15 A 85 O o South Americans 100 O o Why Initial population lost B antigen to genetic drift from Bering strait lost A through second bottleneck Population could be Type O and gene flow for type A The modern theory of evolution Micro evolutionary processes translate into speciation or macroevolution o Microevolution Anagenesis over time o Macroevolution Parent population changes to daughter population Cladogenesis Origin of new species Parent species divides into two daughter species different from each other Problem Can t be tested in Paleontology Biological Species A species is a reproductive community of populations that occupies a specific niche in nature Fixed Evolutionary species o A lineage an ancestral descendent sequence of populations evolving separately from others and with its own unitary evolutionary role and tendencies What is speciation Transformational Speciation A B over