Chapter 3: Evolution, Genes, and Environment
Nature versus Nurture
-Traditionally an either/or argument
Nativism-genetic determinism; innate and inborn.
Empiricism- environmental determinism; blank slate, learning
-"Geniuses and idiots are born, not made"- Sir France Gallman
-"Everyone is born with the same potential".
Nature and Nurture
Today, more focus on interaction of nature and nurture to explain human 'nature'.
Epigenetic- "on" or "over" the genetic information encoded in the DNA--> could
turn a gene on or off. "Epigenetic regulation of the glucocorticoid receptor in
human brain associates with childhood abuse."-Nature Neuroscience, 2009.
o Behavioural Genetics.
Differences (individual variation).
Identical twins raised together or apart. Adoptees can be compared to
"Heredity deal the cards; environment plays the hand." -Charles L. Brewer
Differences (individual variation)
identical twins raised together or apart
“Heredity deals the cards; environment plays the hand.” ~Psychologist Charles L. Brewer (1990)
o Commonalities (human universals)
o Evolutionary Biology + Cognitive Psychology
o Goal is to understand the human mind/brain from an evolutionary perspective
o The design of the mind must have been shaped by natural selection (including
Evolutionary psychologists propose that humans evolved tendencies to think, feel, and
behave in certain ways, and not others because of adaptations. Our mental lives and behavior reflect the evolutionary history of our species, particularly
the adaptive problems that had to be solved such as avoiding predators, eating the right
food, attractive mates, forming alliances, and "reading other people's minds".
The human mind consists of a set of domain-specific information processing modules.
Evolutionary psychologists argue that there are very many (hundreds? Thousands?)of
specialized modules in the human mind.
o Ex. Paternal love as obligatory parental investment
o genes for fathering motivation became “standard equipment” in the genetic
complement of human males, just like genes code for facial hair in males. Still,
there is variation across males (behavioral genetics).
Evolutionary adaptations are general and flexible
o e.g., we have not evolved to understand specific languages, such as French or
English, but rather…
Not all human abilities evolved via natural selection
o your ability to read
3 characteristics of evolved adaptations:
o adaptive, heritable, and universal
innate human characteristics
Attraction to novelty
Desire to explore
but…many aspects of human behavior that probably reflect evolutionary adaptations but
do not increase survival and reproduction in contemporary
Some are evolutionary carry-overs that no longer have any apparent survival value.
o Swimming reflex
o Moro reflex
fats and sugars - evolved tastes Backfires in contemporary environments
Have to consider the environment of evolutionary adaptedness (EEA) - environments in
which a species’ evolutionary adaptations were selected
in which our ancestors lived for millions of years prior to the rise of agriculture
The Pleistocene period: 2 million – 10,000 years ago
Compare this with modern environments to explain maladaptive behavior today
Modern human brain consists of modules from the past
Darwin’s Theory of Evolution by Natural Selection
3 major principles:
o characteristics are passed from one generation to the next
characteristics vary across members of a species
o some individuals will be more successful in their environment than others
o demand for resources produces selective pressure
3. natural selection (“survival of the fittest”)
o how species change, or evolve, over time
o only those members of a species able to compete successfully for limited
resources will survive and reproduce
Darwin’s second “major” book: 1871 On the Descent of Man, and Selection in Relation to
-Darwin needed a theory to explain the many extravagant traits that seem to reduce
survival (e.g. the peacock’s tail).
There are two types:
1. Intrasexual selection (ex. Two males fighting)
2. Intersexual selection (ex. A female choosing the strongest male) The Case of Sex
Evolutionary/Sociobiological view: love as pair-bonding
Requires attraction to opposite sex
Romantic love is an adaptation
Men and women face different selection pressure