Last updated: February 23, 2018
Biological Bases of Behavior III:
Some Notes on Heredity and Evolutionary Psychology (Outline)

Heredity & Behavior

  • Are the sayings true: like father, like son, or, like mother, like daughter?
  • Does craziness run in families?
  • Is biology destiny?

Basic Principles of Genetics

cell to dna nucleus

human male karyotypeChromosomes


Human beings have 23 pairs of chromosomes

                  Family Relatedness]Research Strategies

     Example: Schizophrenic (SCZ) Disorders

concordance rates:

Why is this evidence that SCZ cannot be merely an hereditary disorder, that is, that SCZ is not due solely to genetic influences?

The Interplay of Heredity & Environment

1. Polygenetic determinism

2. Genetic vulnerability (called a "diathesis" in medicine). Thus, diathesis + high environmental stress = disorder.

3. Epigenetics = study of heritable changes in how genes express themselves that do NOT involve modifications to the DNA sequence.

4. Most traits are the result of the combined effects of heredity and environment. (chart below not in the Notes):


The Evolutionary Basis of Behavior

  • Is monogamy natural?
  • Are humans doomed as a species because our minds were fundamentally shaped by the demands of the Stone Age, but we now live in a world of germ warfare, atomic weapons, and the potential to kill the planet?
  • Are men programmed or destined to be unfaithful to their wives?
  • Are women less interested in sex than men are?
  • Is it natural that men mostly look for beautiful women while women mostly look for men who are (potentially) rich or influential?
[Darwin's On the Origin of Species]

[Charles Darwin]Charles Darwin's Theory (1859: On the Origin of Species by Means of Natural Selection)

  • Various physical characteristics or traits emerge due to random genetic changes & an be passed down to subsequent generations.
  • Fitness
  • Natural selection

Modern Refinements = Evolutionary Psychology