LECTURE 14

Question 1

There are three related problems at the intersection of philosophy and science that are fundamental to our understanding of our relationship to the natural world

Answer 1

The mind–body problem, the free will problem, and the nature–nurture problem.

Question 2

Behavioural genetics

Answer 2

The science of how genes and environments work together to influence behavior

Question 3

Twin studies

Answer 3

A behavior genetic research method that involves comparison of the similarity of identical
(monozygotic; MZ) and fraternal (dizygotic; DZ) twins.

There are two types of twins: monozygotic (MZ) and dizygotic (DZ). Monozygotic twins, also called “identical” twins, result from a single zygote (fertilized egg) and have the same DNA. They are essentially clones.
Dizygotic twins, also known as “fraternal” twins, develop from two zygotes and share 50% of their DNA. Fraternal twins are ordinary siblings who happen to have been
born at the same time. To analyze nature–nurture using twins, we compare the similarity of MZ and DZ pairs. Sticking with the features of height and spoken language, let’s take a look at how nature and nurture
apply: Identical twins, unsurprisingly, are almost perfectly similar for height. The heights of fraternal twins, however, are like any other sibling pairs: more similar to each other than to people from other families, but hardly identical. This contrast between twin
types gives us a clue about the role genetics plays in determining height. Now consider spoken language. If one identical twin speaks Spanish at home, the co-twin with whom she is raised almost certainly does too. But the same would be true for a pair of fraternal twins raised together. In terms of spoken language, fraternal twins are just as similar as identical twins, so it appears that the genetic match of identical twins doesn’t make much difference.

Question 4

Quantitative Genetics

Answer 4

The scientific discipline in which similarities among individuals are analyzed based on how biologically related they are.

Scientific and mathematical methods for inferring genetic and environmental processes based
on the degree of genetic and environmental similarity among organisms.

Question 5

Heritability coefficient

Answer 5

An easily misinterpreted statistical construct that purports to measure the role of genetics in
the explanation of differences among individuals.

varying from 0 to 1, that is meant to provide a single measure of genetics’ influence of a trait. In a general way, a heritability coefficient measures how strongly differences among individuals are related to differences among their genes. But beware: Heritability coefficients, although simple to compute, are deceptively difficult to interpret. Nevertheless, numbers that provide simple answers to complicated questions tend to have a strong influence on the human imagination, and a great deal of time has been spent discussing whether the heritability of intelligence or personality or depression is equal to one number or another.

Question 6

Adoption Study

Answer 6

A behavior genetic research method that involves comparison of adopted children to their
adoptive and biological parents