ISS 210 1st Edition Lecture 3 Outline of Last Lecture I Cognitive Style II Arguing About Facts III Types of Cognitive Style Mysticism IV Common Sense V Types of Cognitive Style Rationalism VI Types of Cognitive Style Empiricism VII The Controversy VIII Characteristics of Science IX The Problem of Subjectivity X Meaningless Science XI XII XIII XIV Teleological Functionalism Creationism and Catholicism Public Acceptance of Evolution Non Overlapping Magisteria NOMA Outline of Current Lecture I Louis and Mary Leaky II Virtual Anthropology III Taphonomists and Deposition IV A Leopards Pray V Stratigraphy VI Vulcanic Tuffs VII Chronometrics VIII Trapped Charge Dating IX Species Where do you draw the line X Catastrophism XI Uniformitarianism XII Phyletic Gradualism XIII Punctuated Equilibrium XIV Allopatric Speciation XV Homosapiens Sapiens XVI Cladistics Vs Evolutionary Tree XVII The Disadvantages of Bipedalism XVIII Dentition and Skulls XIX Tooth Enamel Wear Patterns Current Lecture I Louis and Mary Leaky Began research in Olduval Gorge in 1950s Developed teams of highly specialized paleo fill in to gather and interpret fossil and geological evidence II Virtual Anthropology Use of CT scans Removes breccias and other deposits without damaging the skull Provides a non invasive way to examine cranial capacity and other anatomical features General trend in primate evolution has been increasing brain size relatively to body size No Absolute correlation between brain size and intelligence but there may be Why expend energy on building unnecessary structure Much of our anatomy seems to connect with cooling in the brain Allows for comparisons that would not otherwise be possible III Taphonomists and Deposition Taphonomists study what happen to an individual after death Bones forensic anthropology The interpretation of Death Assemblages of fossil remains is critical to getting the interpretation right how bones got there IV A Leopards Pray In 1960s the remains of animals including hominids at Swartkrans in South Africa were taken as evidence that A africanus was a Killer ape and a cannibal The bones were deposited by leopards V Stratigraphy Study of the sequences which sedimentary rocks that often contain fossils were laid down The layer cake effect can be distorted due to folding or in sedimentary basins depressions made by erosion making sequencing difficult Layers can be matched over great distances using Geochemical fingerprinting based on the unique chemical signature of a volcanic eruption Faunaul correlation allows relative stratigraphic sequences but still looking for a date Improved chronometric techniques date volcanic layers and deposits VI Vulcanic Tuffs Stratigraphy of the Afar region in Ethiopia where A afrarensis Lucy was found Note the layers of volcanic deposits that provide a range of dates for the hominid remains between them VII Chronometrics Carbon 14 or radio carbon is radio active isotope of carbon absorbed by living organisms but begins to decay at a fixed rate when they die Useful on specimens less than 40 000 years old Potassium Argon K Ar and recent KR Ar method exploits the decay of radio active potassium into the noble gas argon K Ar in volcanic rocks provides key date for stratigraphic layers 200 000 to several million years Applied to hominid fossils at Olavvai Gorge changed the dates from Leakey s estimate of 600 000 to 1 8 million years ago VIII Trapped Charge Dating Free electrons are trapped in the crystals structures of mineral associated with fossils The number trapped are a function of time Heating empties the electron traps and resets the clock IX Species Where do you draw the line In biology species are the largest populations with in which fully functional interbreeding between individuals is possible Species are defined by a biological boundary reproductive cohesion not morphology Reproductive incompatibility producing sterile offspring Ex mule In paleontology species became segments of lineages defined By the accumulation of morphological novelties By random discontinuities in fossil record X Catastrophism In the late 19th century it was commonly believed that the world had been created in 4004 bc The discovery of thunder stoves fossils led to theory of multiple floods or catastrophes Geology began to identify natural processes that required a much older earth Modern Astronomy requires a much older universe Theory of Catastrophism stated that natural laws were suspended and events happened a different rate than they do today XI Uniformitarianism Charleslyell a geologist stated the principle of uniformitarianism that the natural forces acting today acted in the past and that thy have always worked with the same intensity Change XII Phyletic Gradualism A phylum is the lineage or line of descent of a species and chronicle change over time Evolution was simply a matter of gradual generational changes single modifying lineage Lineages changed due to adaptive response to natural selection The gaps in the record account for but do not explain radical changes The Modern Synthesis saw human evolution as a single minded slog from primitiveness to perfection brought about by gradual generaton to generation change XIII Punctuated Equilibrium Gould and Eldridge noted that species did not change gradually but rather experienced long periods of stability or equilibrium interspersed or punctuated with periods of rapid change Long periods of species stability with brief periods of speciation extinction and replacement Evolution by jerks to quote one of their critics New species appear speciation because they developed else where allopatric due to isolation and environmental differences Model requires mutation as source for genetic variability Genetic drive and bottle necking to establish new traits XIV Allopatric Speciation 1 Local population within a species adapt to their local habitat a Almost always become distinct but maintain potential for reproductive continuity with the rest of their species b Local habitats constantly changing 2 Isolating mechanism disrupts reproductive continuity a New physical variations most likely to become established in small and quasiisolated population b Genetic isolation breaks reproductive continuity 3 The parent and the now independent species are free to compete should contact ever be reestablished between the two 4 Environmental shifts occur too quickly for Natural Selection to react a Rapid colonization to territory by newly