Distinguish Natural Selection from Sexual Selection. Chapter 1: Goetz, A. T., & Shackelford, T. K. Introduction to evolutionary theory and its modern application to human behavior and cognition (pp. 1-20). Evolutionary ideas predate Darwin: Anaximander Greek philosopher (c. 610 BC – c. 546 BC) Authors give us an unreferenced quote: “in water the first animal arose covered with spiny skin and with the lapse of time some crawled onto dry land…” Darwin’s contribution was the major mechanism by which evolution could operate: Natural selection Distinguish Natural Selection from Sexual Selection.

Evolution: Basic Principles Evolution: Change over time; decent with modification Natural Selection: Primary mechanism producing evolution (change over time). There are other mechanisms such as: sexual selection, social selection, drift. Basic principles of NS: Variability: stuff varies Heritability: variation is passed on genetically Competition: limited resources Selection: some variations are advantageous in securing limited resources and tend to passed on more than others = change over time Spencer’s misleading summary of NS: “survival of the fittest.”

Sexual selection Some traits may actually be detrimental to survival but provide an advantage in mating.

Sexual selection: intra-sexual competition Typically male-male competition for mates, resources, and status.

Intra-sexual coalitional competition Chimpanzees are especially well-known for forming male coalitions to challenge other males for dominance.

Other key concepts Modern Synthesis: combo of Darwinian selection with Mendelian genetics. Adaptations: inherited, phenotypic solutions to adaptive problems Byproducts: non-adaptive incidental tag-alongs to adaptive traits. Navel is byproduct of adaptation of umbilical connection of mammalian mother to offspring. Noise: Random non-adaptive characteristics of adaptations or byproducts. Inny vs. outie navel; dry hair, frizzy hair etc. Evolutionary psychology: human mental/emotional functioning as evolved solutions to adaptive problems. Ex: face processing; jealousy. Inputs-decision rules- outputs

More concepts Domain specificity: A psychological adaptation is specific to an adaptive problem, does not apply generally to a range of potential problems. Ex: cheater detection mechanism. Controversy as to how widespread this type of design is. EEA: Environment of Evolutionary Adaptiveness. The original selection pressures which shaped the present adaptation. Inclusive fitness: W.D. Hamilton – fitness should include not just direct offspring but kin offspring as well; gene’s eye view of evolution Connection to sociobiology: EP – greater emphasis on psychological mechanisms and less on current adaptive significance. Humans as “adaption executers, not fitness maximizers.” Key concept: NS cannot make you have alot of offspring, it can only motivate you to engage in those behaviors that in the past were associated with higher rates of reproduction.

Evolutionary basis for male competition Gamete size (cheap sperm vs. expensive eggs) Parental investment (mating vs. parenting effort) Parental certainty (paternal vs. maternal certainty)

Social Selection Some traits help animals get along better in their social groups which in turn increases their survival and reproduction. Ex: more socially skilled female baboons tend to have more surviving offspring.