Ch 3: Genes, Evolution, and Environment Flashcards
Evolutionary psychology
A field of psychology emphasizing evolutionary mechanisms that may help explain human COMMONALITIES in cognition, development, emotion, social practices, and other areas of behaviour
They believe the mind is not a general purpose computer, but evolved as a collection of specialized mental modules to handle specific survival problems (innate human characteristics)
Behavioural genetics
An interdisciplinary field of study concerned with the genetic bases of individual DIFFERENCES in behaviour and personality
Genes
The functional units of heredity; they are composed of DNA and specify the structure of proteins
Chromosomes
Within every cell, rod-shaped structures that carry the genes
Deoxyribonucleic acid (DNA)
The chromosomal molecule that transfers genetic characteristics by way of coded instructions for the structure of proteins
Genome
The full set of genes in each cell of an organism (with the exception of sperm and egg cells)
Researchers have completed a map of the entire human genome; but it doesn’t tell us what a gene does, or how multiple genes interact and influence behaviour
Genetic marker
A segment of DNA that varies among individuals, has a known location on a chromosome, and can function as a genetic landmark for a gene involved in a physical or mental condition
Used to track down genetic patterns of inheritance
Evolution
A change in gene frequencies within a population over many generations; a mechanism by which genetically influenced characteristics of a population may change
Mutation
Changes in genes, sometimes due to an error in the copying of the original DNA sequence during the division of the cells that produce sperm and eggs
Natural selection
How the environment determines whether genetic variations survive. So populations in a similar environment will end up with similar genes that are more successful within that environment
An evolutionary process in which individuals with genetically modified traits that are adaptive in a particular environment tend to survive and to reproduce in greater numbers that other individuals do; as a result, their traits become more common in the population
Mental modules
A collection of specialized and independent sections of the brain, developed to handle specific survival problems, such as the need to locate food or find a mate
List the innate human characteristics
Characteristics that are useful and help aid in survival:
- Infant reflexes; ex: to suck things, helps to nurse and, therefore, survive
- An interest in novelty; ex: looking at and listening to unfamiliar things; babies will even stop nursing to look at someone new
- A desire to explore and manipulate objects; ex: take things apart to see how small components fit together
- An impulse to play and fool around; provides practice in a safe setting, helps prepare for serious adult settings
- Basic cognitive skills; interpreting gestures and facial expressions; by 18 months old children can understand concepts like “more than” and “less than”
Sociobiology
An interdisciplinary field that emphasizes evolutionary explanations of social behaviour in animals, including human beings
Observations of behaviour in non-human animals can be applied to humans
Innate behaviour has been bred into humans to maximize the chance of passing on genes
Nature has selected adaptive psychological traits and social customs; ex: kinship bonds, sexual taboos
Arguments against the “Genetic Leash”
- Stereotypes of gender differences vs actual behaviour
Ex: Females have sex when already pregnant, males stick around to help protect and care for infants
- Convenience vs representative samples
Ex: 1970s studies only included women. Recent studies included men and women, and found that men are just as interested in family relationships as women
- What people say vs what they do:
Ex: Rely too much on answers to questionnaires that do not reflect real life
- The Fred Flintstone problem
Ex: Rely too much on genetic evidence from the Pleistocene age (2 million to 11 thousand years ago); natural selection since then has influenced genes associated with taste, smell, digestion, skin colour, brain function
Ex: Pleistocene age had smaller population; mates chosen based on similarity and proximity, rather than
Social Darwinism
The notion that the wealthy and successful are more reproductively fit than other people
Heritability
A statistical estimate of the proportion of the total variance in some trait that is attributable to genetic differences among individuals within a group
Used to understand how both genes and environment can contribute to human characteristics
Scores closer to 100% mean variability in a group is caused almost entirely by genetics
Scores closer to 50% mean variability in a group is strongly influenced by both environment and genetics
Estimates do not indicate how much of a trait is caused by genetics vs environment, but help researchers determine in which direction to focus further studies
List the main qualities of heritability
- An estimate of heritability applies only to a particular group living in a particular environment
- Heritability estimates do not apply to individuals, only to variations within a group
- Even highly heritable traits can be modified by the environment
Identical (monozygotic) twins
Twins that develop when a fertilized egg divides into two parts that develop into separate embryos
Fraternal (dizygotic) twins
Twins that develop from two separate eggs fertilized by different sperm; they are no more alike genetically than are any other pair of siblings
Intelligence quotient (IQ)
A measure of intelligence originally computed by dividing a person’s mental age by his or her chronological age and multiplying by 100; it is now derived from norms provided for standardized intelligence tests
Measures a general quality that affects most aspects of mental ability
Epigenetics
The study of changes in gene expression due to mechanisms other than structural changes in DNA
Gene expression varies due to random biochemical processes within bodily cells, which geneticists call “noise”; identical twins and cloned animals living in exactly the same environment can differ in appearance and behaviour
IQ test
A heritability study to measure intellectual functioning; most estimates apply only to those mental skills that affect test scores
Likely more valid for some groups than others because the tests are based mainly on samples of white people
Environmental factors that reduce mental ability
- Poor prenatal care
- Malnutrition
- Exposure to toxins
- Stressful family circumstances
Human Courtship and Marriage: Sociobiology vs Evolutionary Psychology
Sociobiologists:
Argue that males and females evolved different courtship strategies in response to survival problems faced by distant ancestors. Called the “Genetic Leash”
Males: adaptive to be promiscuous, attracted to young partners, and want sexual novelty
Females: adaptive to be monogamous, choosy about partners, and prefer security to novelty
Evolutionary Psychologists:
Agree with sociobiologists, find their analogies are simplistic and misleading; and other arguments against the “Genetic Leash”
Ex: sadistic rapists do not help to pass down genes
What is the “Genetic Leash”
The question that asks, “how large an influence does our Stone Age past have on our current courtship and mating customs?”
Evolutionary theorists/psychologists emphasize strategies developed from the Pleistocene era, when humans lived in hunter-gatherer societies, greatly influence the strategies of today
