Genetics, Evolutionary Psych, and Behavior Unit 3C

Intro People have wide differences. People have universal qualities… faces, relationships, conformity, social ranks, grieve, celebrate, worship, play Genes 46 chromosomes (23 Mom, 23 Dad) DNA holds our genetic code Genes either expressed or repressed People are very similar, but the differences draw interest

How to study genetics Nature vs. Nurture (genetics vs. environment) Both matter! Experiments? No! Ethical issues! Twins, twins, twins. They have similar DNA—shows genetics. And… Adopted kids. They have similar upbringings—shows environment.

Groups of interest Identical twins – monozygotic twins – have same DNA. Any differences MUST be due to environment Fraternal twins – siblings – brother/sister but raised with very similar environments Siblings – bro/sis’ – similar DNA, similar environment Virtual twins – step bro/sis’ – dissimilar DNA, similar environment Adopted kids – dissimilar DNA, similar environment Unrelated – dissimilar DNA, dissimilar environment

Nature vs. nurture? Ranking of similarities… Identical twins raised together ID twins raised apart (freaky similarities) Fraternal twins raised together Siblings raised together Siblings and fraternal twins raised separately Virtual twins raised together Two random people Conclusion: Both matter! (but, genetics more so in this case)

Heritability Mark Twain and his story of boys raised in barrels. Caution! This has a trap. Definition = probability that the differences between people are due to genetics Trap: Heritability does not mean something is due to genetics! Rather, see above. So, if heritability is 60% for height… It’s right to say, “60% of the variation in people’s height is due to genetics.” It is wrong to say, “A person’s height is 60% due to genetics.” Mark Twain and his story of boys raised in barrels. Same environment, only genetics differs. So, IQ differences would be due to genes. This would be high heritability.

Practice Heritability for intelligence is about 50%. What would be a correct statement you could make using this stat? What is a common incorrect statement people make using this stat?

Evolutionary psychology Based on Darwin’s theory from the 1800s Summary… Survive Reproduce Pass on genes Mutations – random gene changes, sometimes hurt/help #1-3 Natural selection—nature weeds out bad genes, passes on good genes

Case study Researchers bred foxes, tried to domesticate them Only the most people-friendly foxes were selectively bred; those genes passed on 30 generations later, they had people-loving puppy-foxes

Evolutionists’ world view Survive, reproduce & pass genes—that’s it. Focus on similarities; people are 95% alike genetically Think “cave man”...is that person with a big club a friend/foe? (helps survival) Is that person a hottie & think I’m a hottie? (helps reproduction) Pregnant women get morning sickness, avoid foods (helps reprod.) We all genetically love junk food… …fats and sweets; fat is a reserve (helps survival)

M/F differences (AKA, sex stereotyping 101) Men and women differ. Ex.: ___ seeks sex more. Men, duh. Men more likely to see a compliment as a come-on. Women see sex as relationship, for the long haul. Men want to spread their genes; women want a man to stick around, provide for/protect the family. Men look for…young (20s), athletic build (waist 2/3 hips), smooth- skinned. This adds up to child-bearing. Women look for…slightly older men, mature, dominant, confident (think successful businessman). This adds up to stability & ability to provide for family.

Examples…

Critique of evolutionary psych Criticized as narrow-minded…all we do is strive to survive, reproduce, pass on genes. Many wonder… “Isn’t there more to humanity?”