ANTH1102 1st Edition Exam 2 Study Guide Lectures 7 12 Race and Ethnicity Biological diversity is seen through phenotypes physical expressions of genes thus different phenotypes occur from adaptation to environmental stimuli The biological definition of race is an isolated subdivision of a species based on common ancestry and biological traits However this definition is problematic because humans are not reproductively isolated skin color has a clinal distribution so the best definition of race would be the classification of peoples based on presumed biological similarities Race is a cultural expression with no biological basis so its classifications differ across the world For example hypodescent led to the One Drop Rule in which an interracial relationship the minority parent s race is assigned to the child Another example of culture defining race is the decidedly homogenous Japanese where intrinsic racism or the idea that perceived racial differences are sufficient basis for devaluing groups is common Then there are the Brazilians who have heterogenous multiracial categories and value the idea of an achieved race and style shifting because in their culture racial categories are a historical legacy Lastly many Mexicans affected by colonialism and categorization view intermixed races as one race combination of indigenous and European bloodlines Ethnicity is identification with an ethnic group whether individuals identify themselves or the individuals are identified by others based on cultural descent biological descent historically known geological origins shared language and shared sense People who identify with a specific nation classify their nationality Ethnic conflict has arisen over prejudice of stereotypes causing discrimination de facto in practice but not necessarily lawful e g racial profiling or de juro under law e g segregation and apartheid These ideas have led to ethnocide the deliberate destruction of an ethnic culture not to be confused with genocide that focuses on systematic destruction of racial political or cultural groups Evolution Evolution is simply defined as change over time biological evolution states that species change and give rise to new species Evidence of this is supported by studying fossil records and living species There exists many theories on human evolution including catastrophism transformism and uniformitarianism proposed by Sir Charles Lyell who believed current earth processes are the same as those in the past e g Bryce Canyon Utah Charles Darwin and Alfred Wallace created a theory to explain change the origins of species and natural selection called Darwinian Evolution The principles were variation inheritance differential survival and reproduction struggle for existence In conclusion natural selection meant that those forms most successful at reproducing in specific environments are selected thus changing species over time However Darwin missed some important keys mechanisms of inheritance origin of variation and population genetics Mendelian Genetics described further the ideas of genetic inheritance by studying pea plants and using Punnett Squares to determine phenotypes of offspring by multiplying factors genes from parents There are homozygous gene combinations that consist of two of the same genes both dominant or recessive and there are heterozygous combinations that consist of two different genes one dominant one recessive There are also different types of cell division mitosis between regular cells and meiosis between sex cellschromosomes During meiosis chromosomes intertwine and exchange segments of DNA which is called crossing over F Macroevolution is the genetic change in a population or species over time while microevolution is the change in genetic frequencies alleles in a population over few several or many generations There are four forces of macroevolution that affect geological distribution of varied human traits natural selection mutations random genetic drift and gene flow Punctuated equilibrium Stephen Jay Gould and Niles Eldridge 1972 describes long periods of stability with occasional evolutionary leaps extinction and succession replacement mutations speed up evolution Adaptation a series of beneficial traits is one of the main reasons that humans can survive for so long and in so many diverse environments This is studied and presented by Allen and Bergman s Rules when they describe how certain body types are selected for in certain climate temperatures in hot climates tall thin bodies are common and cold climates yield short stocky body types because of benefits that helped them survive and have reproductive success They also noticed the Quechua Southern Peru and Sherpa Nepal cultures that live at high altitudes and have biological traits that allow them to live in such environments