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Transcript
ANG 6930 Proseminar in Anthropology IIA: Bioanthropology Day 2 ANG 6930 Prof. Connie J. Mulligan Department of Anthropology This week Science and Evolution Reading The Human Species, Chpt 1(pp 12-29) and Chpt 4 Course packet Park MA. 2005. Biological Anthropology, An Introductory Reader, Chpt 9 (pp 40-44), Natural Selection (1858), Charles R. Darwin and Alfred Russel Wallace Mayr E. 1997. “What is science?” in This is biology: The science of the living world, pp 24-44. Cambridge: Harvard University Press Scott EC. 1997. Antievolution and creationism in the United States. Annual Review of Anthropology 26:263-289 Talbot M. 2005. Darwin in the Dock. The New Yorker, pp 66-77 Berkman MB et al. 2008. Evolution and Creationism in America’s Classroom: A National Portrait. PLoS Biology, 6:0920-0924 Next week Genetics and the development of evolutionary theory Mendelian and molecular genetics Population genetics Evolutionary development biology (Evo Devo) Reading The Human Species, Chpts 2 (Human genetics), 3 (Evolutionary forces), 8 (Paleoanthropology) Course packet Tattersall I. 2000. Paleoanthropology: The last half-century. Evolutionary Anthropology 9:2-16 Foley R. 2001. In the shadow of the modern synthesis? Alternative perspectives on the last fifty years of paleoanthropology. Evolutionary Anthropology 10:5-14 Carroll SB. 2003. Genetics and the making of Homo sapiens. Nature. 422:849-857 “Beyond Stones and Bones”, Newsweek, March 19, 2007. Topic and abstract for journal analysis is due Journal analysis Your topic (the relevant question(s) and which other subfield you will be examining) and an abstract (<200 words) including your search strategy (which journals are you using and why) is due at the beginning of class on Jan 21. In your abstract, describe the problem you are addressing and some of the history of this issue. Be sure to specify your two additional journals, and why you chose them, as well as the other subfield of anthropology that you will be studying. I encourage you to discuss your topic with me in advance, in person or by email. The final paper is due at our last class, Feb 18. Turn in your original (graded) abstract with the final paper From last week Current hot topics on humans Top 10 mysteries about humans http://www.livescience.com/history/091026-top10origins-mysteries.html Top 10 things that make humans special http://www.livescience.com/culture/091030origins-top10-special.html Anthropology Important to remember that a strength of anthropology is its holistic approach What’s the difference between cultural anthropology and sociology? What’s the difference between biological anthropology and biology? Holistic view is not limited to the 4 anthropology subfields, but any relevant field Many Anthro departments are splitting along subfield lines Why do you think more anthropological research is not truly interdisciplinary? How could you make your research relevant to someone outside your subfield? Balaresque et al. 2007 Demography Migration/colonization Population origins Semitic speakers Admixture Out of Africa Peopling of New World Puerto Ricans Adaptation Peopling of the Americas Expansion out of Africa Natural selection Skin color Agriculture/domestication Disease Origin/intro to naïve pop’s Genetic/cultural risk factors Domestication of the donkey Modified from Balaresque et al. 2007 Origin and expansion of Semitic speakers Genetic and cultural components to ethnicity and health Chpt 1 - Science and Evolution Development of evolutionary thought Darwin and natural selection Misconceptions about evolution Science as a way of knowing Science, evolution, and creationism Landmarks in Euro-American Thought about Human Origins and Diversity Age of European Exploration Years A.D. Darwin publishes On the Origin of Species Development of Evolutionary Thought Ancient roots – differences and origins Renaissance – empiricism and science 17th-18th centuries – naturalism 1800-1859 – Racial origins 1859-1900 – Evolution and racial origins 1900-1950 – Description and classification 1950-present – New Physical Anthropology Pre-Darwinian Theories and Seeds of (R)evolution Pre-Darwinian thought Ancient Greek philosophy Aristotle (384-322 B.C.) Greek philosopher and naturalist Historia Animalium describes similarities between man, apes, and monkeys Static, unchanging view of the world Differences attributed to position in the scala naturae (Great Chain of Being) Aristotle’s notion of scala naturae did not incorporate racial hierarchy Argued for environmental causes of variation Wooly hair of Africans due to harsh, arid climate Straight hair of Thracians and Scythians due to moist air Carolus Linneaus (1707-1778) Swedish botanist and founder of taxonomy Epitomized focus on description and classification Systema Naturae (17351766) Identified two-dimensional structure of nature, as opposed to one-dimensional “Great Chain” Great Chain vs Linnaean Taxonomy Source: Marks (1995) Human Biodiversity Linnaeus’s Classification of Humans Homo sapiens in order Primates Four geographic varieties mix culture and biology H. sapiens europaeus H. sapiens asiaticus H. sapiens americanus H. sapiens afer George Louis Leclerc, Comte de Buffon (1707-1788) French naturalist Opposed Linnaeus No unit higher than species Species comprise Great Chain of Being Dismissed evolutionary implications of Linnaean ideas Posited microevolution in response to environment, but denied macroevolution Buffon and Human Variation Buffon rejected classification as goal of study, aimed to describe and explain diversity Varieties of the Human Species (1749) How is variation patterned? What explains patterns of variation? Buffon and Linneaus represent two strains of thought in 20th century anthropology Georges Cuvier (1769-1832) French zoologist and founder of paleontology Embraced Linnaeus’s nested hierarchy, but not evolutionary implications Best remembered for catastrophism Mass extinctions, repopulation gives appearance of change Consistent with Biblical view Jean Baptiste, Chevalier of Lamarck (1744-1829) French aristocrat Regarded classification as sterile and theorized about process of evolutionary change Inheritance of acquired characteristics Organism altered during lifetime by environment and behavior Change inherited by offspring James Hutton (1726-1797) Scottish geologist Developed principle of uniformitarianism (1785) Same geologic processes (erosion, continental drift) operate today as in the past Earth has long history Supernatural theories not required to explain history Earth’s geology shaped by processes observable today e.g. Deep soils formed by the weathering of bedrock over 1000s of years Sir Charles Lyell (1797-1875) Scottish geologist Promoted and extended principle of uniformitarianism Three-volume Principles of Geology (1830-1833) Darwin – “I always feel as if my books came half out of Lyell’s brain.” Charles Darwin (1809-1882) Born into intellectual family in northern England Enrolled in medicine, then graduated in theology Joined HMS Beagle in 1831 as “unpaid gentleman scholar and naturalist” Voyage of the HMS Beagle Darwin and Wallace Darwin outlined theory of natural selection in 1837 20 years later, young Wallace developed same theory Darwin and Wallace copresented at Linnaean Society of London (1858) Darwin published On the Origin of Species a year later Alfred Wallace 1823-1913 Darwin’s observations Much morphological variation Variation made sense in terms of environment Creatures in cold climates had fur Birds in areas where insects live deep inside tree trunks have long beaks Darwin’s Postulates Infinite ability of populations to grow, but finite ability of environments to support growth Malthus showed that the planet can not support uncontrolled growth, i.e. a large percentage of offspring will die and Darwin helps provide the answer as to who will die Within populations, organisms vary in ways that affect ability to survive and reproduce Variations are transmitted from parents to offspring Natural selection – evolution by variation and selective retention An Example – Darwin’s Finches Darwin identified multiple species of finches on Galápagos Islands, attributed special role in his thinking Drought and Darwin’s Finches Natural experiment– severe drought—tests Darwin’s postulates As food supply shrank, finch population declined Beak depth affected survival Parents and offspring had similar beak depths Darwin’s Finches Directional selection Beak depth influences individual’s probability of survival Distribution of beak depth shifts to right due to selection Darwin’s Finches Balancing selection Selection maintains status quo when most common type is best adapted Selection required to keep populations the same, not just to change Individual Selection Selection arises from competition among individuals, not among populations or species Example – individual reproductive success vs species’ survival Selection may favor high individual fertility, even if population growth threatens survival of species Evolution of Complex Adaptations Small variations are important Continuous, not discontinuous traits important Complexity arises from accumulation of small random variations Typing monkeys - “Methinks it is like a weasel.” Chance of randomly typing monkeys reproducing Shakespeare - ~ 1 in a trillion. Same as chance of randomly producing a human eye in a single trial Convergence - complex adaptations have evolved independently multiple times Selection favors intermediate phenotypes Selection of Intermediate Steps Living gastropod mollusks illustrate intermediate steps between eye cup and camera-type eye Rates of Evolutionary Change 14 living species in Galápagos All descended from single species within last half million years Evolution of Evolutionary Theory Darwin could not explain how variation was maintained Assumed blending inheritance Could not explain evolution beyond original range of variation Acceptance of Darwinian mechanisms awaited rediscovery of Mendelian genetics Modern Synthesis (1930-1950) Evo-Devo (1980-present) Science and Creationism What is Science? [Empirical science] is systematic description and classification of objects, events, [and] processes, and the explanation of those events and processes by theories that employ lawful regularities, all of the descriptive and explanatory statements employed being testable against publicly observable data. O’Meara, 1989 Science Is… Empirical Systematic and explicit Theoretical, explanatory, predictive Self-critical, reflexive, based on testing Public Creationist Claims “Evolution is only a theory” Actually, evolution is both a fact and a theory Fact is “an observation that has been repeatedly confirmed and for all practical purposes is accepted as ‘true.’” Theory is “a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.” National Academy of Sciences Creationist Claims “Evolution is unscientific, because it is not testable or falsifiable.” Microevolution and macroevolution Fossil record and macroevolutionary hypotheses “Living things must be products of intelligent design, because natural selection could not produce some complex beings.” Evolution of camera-type eye Convergence Chpt 4 - Speciation and Phylogeny Overview Microevolution macroevolution Species concepts Biological species Ecological species Evolutionary forces Systematics, phylogeny, and taxonomy Definitions Microevolution Changes in allele frequencies over relatively short time periods/small geographic ranges/small genomic ranges Evolution over short time periods Occurs in our lifetime, i.e. is observable to all of us Macroevolution Changes in allele frequencies over relatively long time periods/large geographic ranges/large genomic ranges Evolution over long time periods Creationists have problem with macroevolution b/c they say we can’t directly observe macroevolution We can’t do million year experiments, but we can make testable predictions, like in geology or astronomy What Are Species? Species are real biological categories, not abstractions Controversy about how species are defined Biological species concept Paleospecies are more abstract concepts Group of organisms that naturally interbreed and produce fertile offspring Ecological species concept Natural selection plays important role in species differences Reproductive isolation not necessary Species occupy different ecological niches, but are not necessarily physically isolated from each other Phylogenetic species concept Some level of genetic variation is chosen to define different species Modes of Speciation Anagenesis Cladogenesis Phylogeny and Systematics Phylogeny refers to evolutionary relationships among group of species, often depicted as a “family tree” What is the “outgroup” in this tree? Systematics is construction of phylogenies Taxonomy is use of phylogenies in naming and classification Approaches to systematics Evolutionary systematics Considers all homologous traits, primitive and derived Based on descent and overall similarity Complex algorithms to evaluate genetic distance or coalescence and translate that relationship into a tree Cladistics Argues that phylogenies should be constructed only on shared derived traits Much simpler, less sophisticated and probably less realistic Natural selection Mechanism for evolutionary change favoring the survival and reproduction of some organisms over others because of their biological characteristics. Requirements: Variation must exist a priori in order for natural selection to act, i.e. natural selection does not create a variant but it ‘prefers’ it Preferred variant/phenotype must act in such a way as to influence fitness of offspring, i.e. Alzheimer’s will not be selected against b/c it occurs late in life long after childbearing years Misconceptions of evolution and natural selection Bigger is better Newer is better Faster is better Natural selection always works Evolution has a direction or goal Natural selection always produces perfect structures All structures are adaptive Current structure reflect initial adaptations Natural selection will solve every problem – Will natural selection solve problem of stress-based disease? What is evolution? From a genetic perspective, not phenotypic At the most basic, causative definition What is evolution? Changes in allele frequencies over time What are the evolutionary forces that can change allele frequencies over time? What are the evolutionary forces that can change allele frequencies over time? Mutation Natural selection Genetic drift Gene flow What are the evolutionary forces that can change allele frequencies over time? Mutation Introduces a new variant, initially at very low frequency Natural selection Genetic drift Gene flow What are the evolutionary forces that can change allele frequencies over time? Mutation Natural selection Introduces a new variant, initially at very low frequency Alleles that increase fitness exhibit an increase in freq Alleles that decrease fitness exhibit a decrease in freq Balancing selection/heterozygote advantage = heterogzygote has selective advantage so frequencies of both alleles are selected to be in balance (sickle cell allele of hemoglobin protein) Genetic drift Gene flow What are the evolutionary forces that can change allele frequencies over time? Mutation Natural selection Alleles that increase fitness exhibit an increase in freq Alleles that decrease fitness exhibit a decrease in freq Balancing selection/heterozygote advantage = heterogzygote has selective advantage so frequencies of both alleles are selected to be in balance (sickle cell allele of hemoglobin protein) Genetic drift Introduces a new variant, initially at very low frequency Random change in allele frequency from generation to generation Gene flow What are the evolutionary forces that can change allele frequencies over time? Mutation Natural selection Alleles that increase fitness exhibit an increase in freq Alleles that decrease fitness exhibit a decrease in freq Balancing selection/heterozygote advantage = heterogzygote has selective advantage so frequencies of both alleles are selected to be in balance (sickle cell allele of hemoglobin protein) Genetic drift Introduces a new variant, initially at very low frequency Random change in allele frequency from generation to generation Gene flow One individual moves into a new population and reproduces there New genes are introduced into a population Gene flow makes 2 populations more similar No gene flow → reproductive isolation → genetic divergence → speciation What are the evolutionary forces that can change allele frequencies over time? Mutation Natural selection Genetic drift Gene flow In reality, all 4 forces, or a subset, can act at the same time Bioethics Review of research involving human subjects Federal regulations require that all research involving human subjects be approved by an IRB prior to the research Institutional review board = IRB Virtually all universities and research institutes will have their own IRBs Composed of professors/scientists who volunteer their time Must be research – anything commercial is not subject to same regulations, e.g. if someone pays to have genetic typing performed or forensic case work or contract archaeology Also excludes general medical practice, i.e. distinction between accepted and experimental therapy What is a human subject? A human subject is a living individual about whom a researcher obtains: Data through intervention or interaction w/ the individual Identifiable private information IRB regulations do not cover: Dead persons – no protection for the sample of someone who has died Samples that are already collected and that have no identifying information (i.e. are anonymous) Goal of IRB review To safeguard the rights and welfare of human subjects participating in biomedical and behavioral research Guided by the Belmont Report The Belmont Report Ethical Principles and Guidelines for the Protection of Human Subjects of Research The National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research April 18, 1979 Written in response to past abuses of human subjects in biomedical research WWII Abuses of concentration camp victims Tuskogee Syphilis Project Gov’t sponsored study (1932-1972) that denied effective treatment for syphilis to 399 African-American men in order to document the natural history of the disease Three basic principles Belmont Report Respect for persons Subjects must be given the opportunity to choose what will or will not happen to them Beneficence Principle of informed consent and the consent process (information, comprehension and voluntariness) “do no harm” “maximize possible benefits and minimize possible harms” Extends to both investigator and society Justice Requires that there be fair procedures and outcomes in the selection or subjects, both individually and socially (no one asked to unfairly bear burdens) Projects in which the study populations are intimately involved with the project Iceland – National human genome project deCode Genetics, an Icelandic start-up genomics company, spearheaded a project to map the genome of the Icelandic people as part of a larger medical database African Ancestry project Provides DNA testing to determine indigenous African paternal and maternal lineages among African Americans deCode Genetics Iceland is ideal location for a genetic disease association study Historically small population (~50,000 19th century & ~275,000 today) Relatively homogeneous and comparatively isolated Disease candidate genes may be easier to identify Detailed genealogical records for generations Detailed medical records dating back to 1915 In 1998 Icelandic parliament passed a bill authorizing the construction of a national medical database Lots of controversy, some detractors, but general Icelandic public seems to be in favor of project Informed consent as far as medical records goes was based on the principle of presumed, rather than informed, consent, i.e. people had to specifically request that their medical records not be used Many papers have identified genes involved in schizophrenia, heart attacks, asthma, pain, vascular disease, diabetes, etc African Ancestry project Motivated by African-Americans’ desire for more information about their ancestry There is only limited historical info available for African-Americans prior to their enslavement From 1619-1850, millions of indigenous west and central Africans were enslaved Primarily from Senegal south through the Cape of Good Hope and north along eastern Africa to Cape Delgado African Ancestry project, cont Spurred by African Burial Ground project In 1991, human remains were uncovered from an 18th century burial ground of enslaved African in lower Manhattan African American community became a major contributor (both financial and intellectual) to a research project with these aims: What are the origins of the population? What was the physical quality of life in 18th century NYC? What can the site reveal about the biological and cultural transition from African to African American identities? My experiences Panama Explaining my research to indigenous groups in Panama Genetics is my way of understanding history Collecting trip in Panama w/ Panamanian colleague Different decision-making process How to inform an indigenous person about my research? Yemen and Mongolia Different experience – completely positive and enthusiastic Bottom line Best research involves research subjects from the beginning and throughout project Best research honors the beliefs and goals of the research subjects Don’t expect them to buy into “greater good” argument because that is a standard of our culture, not all cultures Best research assumes that research subjects can be educated about the research as long as you put yourself in their position Discussion questions Scientists and the general public Do scientists/the general public have a “right” to learn about the human past? Do scientists/the general public have a “responsibility” to learn about the human past? Individuals Do individuals have a “responsibility” to participate in research for the common good? Do individuals have a “right” to participate in research for the common good?