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MSU ISS 210 - Paleoanthropology

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ISS 210 1st Edition Lecture 3 Outline of Last Lecture I. Cognitive StyleII. Arguing About FactsIII. Types of Cognitive Style: MysticismIV. Common SenseV. Types of Cognitive Style: RationalismVI. Types of Cognitive Style: EmpiricismVII. The “Controversy”VIII. Characteristics of ScienceIX. The Problem of SubjectivityX. “Meaningless Science”XI. Teleological FunctionalismXII. Creationism and CatholicismXIII. Public Acceptance of EvolutionXIV. Non-Overlapping Magisteria (NOMA)Outline of Current Lecture I. Louis and Mary LeakyII. “Virtual Anthropology”III. Taphonomists and DepositionIV. A Leopards PrayV. StratigraphyVI. Vulcanic TuffsVII. ChronometricsVIII. “Trapped-Charge” DatingIX. Species: Where do you draw the line?X. CatastrophismXI. UniformitarianismXII. Phyletic GradualismXIII. Punctuated EquilibriumXIV. Allopatric SpeciationXV. Homosapiens Sapiens XVI. Cladistics Vs. Evolutionary TreeXVII. The Disadvantages of BipedalismXVIII. Dentition and SkullsXIX. Tooth Enamel Wear PatternsCurrent LectureI. 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 possibleIII. 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 leopardsV. 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 eruptionFaunaul correlation allows relative stratigraphic sequences (but still looking for a date) – Improved chronometric techniques date volcanic layers and depositsVI. 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 themVII. Chronometrics– Carbon-14 or radio carbon is radio active isotope of carbon absorbed by living organismsbut 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 agoVIII. “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” – ChangeXII. 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 changeXIII. 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 traitsXIV. Allopatric Speciation1. Local population within a species adapt to their local habitata. Almost always become distinct but maintain potential for reproductive continuitywith the rest of their speciesb. Local habitats constantly changing2. Isolating mechanism disrupts reproductive continuitya. New physical


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MSU ISS 210 - Paleoanthropology

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