Chapter 3 – Genes, Evolution, and the Environment

I. What Are Genes?

A. Located on chromosomes, 23 pairs per person

B. Consist of small segments of DNA

1. DNA: adenine, thymine, cytosine, guanine

C. All together form Human Genome

D. Identified via linkage studies, genetic markers

II. What Is Evolution?

A. Changes in gene frequencies over time

1. Within a population, not an individual

2. Over many generations, not within a generation

B. Why/how do genes change?

1. mutation

2. natural selection (match of genetic to environmental fitness)

C. Issues in evaluating evolutionary psychology

1. can be misled by retrospective (post-hoc) thinking

2. does NOT speak to current-day adaptiveness

III. Innate Human Characteristics

A. Reflexes (e.g., rooting, sucking)

B. Novelty preferences

C. Exploration/manipulation of objects

D. Playing

E. Basic cognitive skills

1. basic concepts of numbers, relativity, identification

2. language capacity (e.g., Chomsky’s “language acquisition device”)

F. Innate sex differences??

IV. Heritability

A. A population statistic, not an individual one

B. Proportion of variance due to genetic diffs within group

C. Will be higher in more similar environments, lower in more diverse environments

D. How can heritability be calculated?

1.  Family studies:  compare rates in gen’l pop vs. families of probands

                2.  Twin studies:  concordance rates in DZ vs. MZ twins

                3.  Adoption studies:  concordance rates between kids and biol. vs. adoptive parents

V. Nature versus Nurture

A. More than just genes

1. gene expression

2. polygenic traits

B. Gene-environment interactions

C. Importance of diversity for species continuity