Behavior & Genetics Genes, Environment, & Behavior: Twins are made when the fertilized egg splits into two eggs with the exact same mixture of genes Temperament, Heredity, & Genes: Temperament is an individual's characteristic emotional reactivity and intensity (“sociability” or “shyness”) Twin Studies & Adoption Studies: Twin and Adoption studies allow us to process the “nature” vs. “nurture” debate Monozygotic Twins are identical twins (result from a single fertilized egg) → share 100% of their genes Dizygotic Twins are fraternal twins (result from two separately fertilized eggs) Heritability: Heritability helps explain the variation of traits in a population that is due to genetic makeup (population dependent!) Heritability increases if environmental factors are in check and decreases if environment is not in check (i.e. one identical twin grows up in the rainforest and the other identical twin in Beverly Hills) - Regulatory Genes: A vast majority of DNA don’t really code for proteins but instead regulate the expression of other genes (about 95% of genes have regulatory functions) Epigenetics is the study of the changes in gene expression resulting from changes to something other than the DNA sequence Methylation (silencing) and acetylation (activating) does this Gene Environment Interaction: Genes and environment are important components for behavior Gene expression can affect environment and environment can affect gene expression (i.e. think of a beautiful baby given lots of love while an ugly baby is given not much love, making it more likely to develop depression) We begin to think of it as nature through nurture. As opposed to them opposing one another, they go hand in hand 1. 2. 3. Adaptive Value of Behavioral Traits: Ethology is the scientific study of animal behavior in the natural environment (rests on observation) 3 Behavior Types: Innate behavior is behavior that is genetically programmed, such as inherited and intrinsic behaviors (i.e. behaviors present in animals that are raised even in total isolation) Learned behavior is behaviors that are not inherited and extrinsic (acquired only through observation and experience) Complex behavior refers to behaviors between innate and learned (i.e. insects that can fly know how to fly, but also learn to be more efficient over time through exposure to other insects)