Week 3 Flashcards
nature nurture debate
the influence of genetics and environment have on human development
why is it difficult to answer the nature-nurture debate
With humans, we can’t assign babies to parents at random, or select parents with certain behavioural characteristics to mate merely in the interest of science. In typical human families, children’s biological parents raise them, so it is very difficult to know whether children act like their parents due to genetics or environmental reasons
behavioural genetics
the empirical science of how genes and environments combine to generate behaviour
Easiest opportunity to observe behavioural genetics
adoption study
Adoption study
A behaviour genetic research method that involves comparison of the similarity of identical and fraternal twins
Monozygotic twins
Also called “identical” twins. Result from a single zygote and have the same DNA
Dizygotic twins
Also known as “fraternal” twins. Developed from two zygotes and share 50% of their DNA
nature nurture studies
We can do these studies on siblings and half siblings, cousins, twins who have been separated at birth and raised separately, or with entire extended families
Contentions about nature-nurture
Intensified because quantitative genetics produces a number called a heritability coefficient, varying from 0 to 1, that is meant to provide a single measure of genetics’ influence on a trait
Heritability coefficient
An easily misinterpreted statistical construct that purports to measure the role of genetics in the explanation of differences among individuals
Quantitative genetics
Developed in the 1920’s; DNA was discovered by Watson and Crick in the 1950s; the human genone was completely sequenced at the turn of the 21st century
What have we leanred about nature-nurture
The more genetically-related people are, the more similar they are for everything. Genetic influence on behaviour is a relatively recent study. The best predictors of an adopted child’rs personality or mental health are found in the biological parents he or she has never met, rather than in the adoptive parents who raised them. No behavioural traits are completely inherited, so you can’t leave environment or genes out alltogeher
Outcome of the nature nurture debate
Everything has turned out to be at least somewhat heritable, yet nothing has turned out to be absolutely heritable, and there hasn’t been much consistency as to which traits are more heritable and which are less heritable once other considerations are taken into account
Heritability of a trait
not simply a property of that trait, but a property of the trait in a particular context of relevant genes and environmental factors
Issue with the heritability coefficient
it divides traits’ determinants into two portions-genes and environment-which are then calculated together for the total variability
The way genes integrate
is complex. For many traits, genetic differences affect behaviour under some environmental circumstances but not others-a. phenomenon called gene-environmental interaction, or GxE
Effects of a behavioural trait
for most behavioural traits, the effects are so small and distributed across so many genes that we have not been able to catalog them in a meaningful way
one of the most important things modern genetics has taught us
Almost all human behaviour is complex to be nailed down even from the most complete genetic information, unless we’re looking at identical twins. The science of nature and nurture has demonstrated that genetic differences among people are vital to human moral equality, freedom, and self-determination, not opposed to them
Evolution
Change over time
Why do certain traits and behaviours develop over time
they are advantageous to our survival
when is physical survival important
only if it eventually contributes to successful reproduction
Reproductive success
the engine of evolution by natural selection
natural selection
Differential reproductive success as a consequence of differences in heritable attributes. In order for our genes to endure over time, we have inherited adaptive, psychological processes designed to ensure success
Adaptions
evolved solutions that historically contributed to reproductive success
First class of adaptions
Called survival adaptions
Survival adaptions
mechanisms that helped our ancestors handle the “hostile forces of nature”. For physical survival