Evolution, Genetics, and Experience

Evidence for Macroevolution• The fossil record• Striking structural similarities orhomologies• Selective breeding of plants and animalsex: dog species

Brief History of Human Evolution• Two types of hominids:Australopithecus and HomoScientists believe:Australopithecus evolvedapprox: 6 mya in Africa fromapesHomo species evolved fromAustralopithecus approx 2mya

Interesting Note:• Humans have had larger brains,opposable thumbs, and havewalked upright for over 100,000years• Artistic works did not appear untilapprox 40,000 yrs ago• Writing did not appear until 3,500yrs ago• Why?

Forces Behind Human Evolution• Natural selection• Mutation• Random genetic drift• Population mating structure• Culture

Natural Selection• 3 types:• Directional selectionex: human brain size• Stabilizing selectionex: human birth weight• Disruptive selectionex: no known examples in human evolution

Mutations• Mutation: an error in the copying of DNA• 2 types: somatic and germinal• Most mutations are in somatic cells• Germinal mutations can introduce newgenetic material-source of variation• More likely to be passed on if beneficial orneutral

Random Genetic Drift• Changes in allele frequencies over timedue to chance and chance alone• Genetic drift varies with population size• Effects of genetic drift decrease with largerpopulations

Population Mating StructureIncludes:geographical and physiologicalisolationimmigration/emigrationmate preferences-sexual selection

Culture• Culture: the transmission of informationand behavior from one generation to thenextex: pass on info about medicine andsanitationCan influence evolution:ex: cultural ideas about abortion, birthcontrol, etc.

Culture Cont.• Travel allows people all over the world tomeet and mate• Humans no longer have geographicallyisolated populations

Evolution and Human Behavior• Many behaviors weexperience today maybe a product ofevolution• Ex: article about maleand female matepreferences

Human Mate Preferences• Differences in matepreferences betweenmales and females• Are these evolvedbehaviors?• Do these preferencesstill apply today?

Human Evolution and OtherAnimals• We tend to treat humans differentlythan other animals-we usually cite mental or emotional abilitiesto support this• Are humans somehow different fromother animals?• If humans are or are not different,what ethical issues arise concerningtreatment of animals?

Evolution and Behavior• What other traits or behaviors may be aproduct of evolution?• Fear of spiders/snakes• Innate behavior of babies• Others?

Are we still evolving?

What would be required for humanevolution to occur?• Ex: evolution can be caused byenvironmental changes that favor oneform of a trait over another• However, humans are able to alter theenvironment• Could an environmental process such asglobal warming influence evolution?