What is an example of a taphonomic process? Why are dinosaur bones and Indiana jones not examples of archaeology? What are the three goals of archaeology? What kind of environments limit decay? What is the Pompeii premise? Biology and Evolutionary Theory – PowerPoint 2 Physical Anthropology: The study of human evolutionary biology and variation. Data are obtained from the fossil record, living humans and our primate relatives. Evolutionary Theory: Loosely defined, evolution means change through time. We are specifically concerned with origins, 1. Progressive Evolution : Herbert Spencer; Evolution proceeds from simple to complex. Adaptation is viewed as the predictable/expected consequence of evolution. 2. Inheritance of acquired traits : Jean Baptiste Lamarck; species evolve as they interact with their environment, passing changes to their offspring. Adaptation is viewed as a one-step process based on need of the organism. 3. Natural Selection : Charles Darwin; organisms evolve as a result of natural selection of variants which originated independently. Variation in color and break size among galapogos finches. In The origin of species ( 1859), Darwin argues that organisms possessing beneficial variations of traits experience differential reproductive success. Neo-Darwinian Evolution is a Two-step Process Creation of Variation - we now know comes from the random and undirected processes of mutation and recombination Natural Selection - primarily a negative force that acts on variation. All remaining variation is subject to competition as measured by differential reproductive success - or fitness. The process whereby organisms better adapted to their environment tend to survive and produce more offspring. Neo- Darwinian theory views adaptation as the result of Natural Selection, so evolution lacks a direction or goal. Other Major Evolutionary Processes Genetic Drift: In small populations, genetic drift may cause random changes or fluctuations in gene frequencies. Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce. o These random effects are caused by sampling variation. Variation represented by a founding population creates a founder effect. These can also be caused by a bottleneck event. Founder effect: The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors. The Bottleneck Effect occurs when there is a disaster of some sort that reduces a population to a small handful, which rarely represents the actual genetic makeup of the initial population. This leaves smaller variation among the surviving individuals. Gene Flow - The transfer of genes from one population to another.