Last updated: September 29, 2029

Class 16: 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

[Generic Family Relatedness]Research Strategies

1. Family studies 2. Twin studies 3. Adoption studies

     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?

              per genome4. Genome Mapping (Genome Wide Association Studies, GWAS)

The Interplay of Heredity & Environment

1. Polygenetic determinism

Single Gene Disorders Multiple Gene - Polygenetic Disorders
cystic fibrosis
alpha- and beta-thalassemias (less hemoglobin than normal)
sickle cell anemia (sickle cell disease)
Marfan syndrome (connective tissue disorder)
fragile X syndrome
Huntington's disease
hemochromatosis (too much iron stored)
heart disease
high blood pressure
Alzheimer's disease

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 (see chart below):


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. He didn't know the actual mechanism of genes (i.e., DNA), but knew there was some physical mechanism involved in how living creatures develop.
  • Fitness
  • Natural selection

Modern Refinements = Evolutionary Psychology