Evolutionary Psychology and Cultural Impacts




The Nature -Nurture debate echoes on in psychology where nativists like Sir Francis Galton suggest that our genetics are all important and environmentalists like John B. Watson suggest that our circumstances and experiences are all important.


Part I: Nature


Basic Concepts

Chromosomes are the basic structural units of heredity which are composed of DNA, normal humans have 23 pairs of chromosomes with the last pair being the sex chromosomes ( XX-female; XY-male).

 Gender Identity &, Hormones The mysteries of gender Listen to Between XX & XY

Genes are the basic functional units of heredity which are located on chromosomes.

Genome is the complete set of genetic information that makes up an organism. Fig 3.1

Evolutionary psychology is a branch of psychology that focuses on the evolutionary history of humans as it plays a causal role in the behaviour and psychological characteristics of people today.

Comparative psychology is the study of psychological traits or abilities across species and is usually seen from and evolutionary perspective.

Sociobiology is an interdisciplinary field that attempts to explain human social behaviour in terms of comparison with other species and evolutionary history.
A favourite topic for sociobiologists is sexuality and mate selection.

Behavioural Genetics is the study of relative causes of genes and environment. Emphasis is on the genetic bases of individual traits. 



Natural Selection is a process hypothesized by Charles Darwin to be the central mechanism for the evolutionary development of species and the creation of new species from other ones.

The major components of this theory are the contribution of genetic inheritance in terms of traits that vary within and between species and the environmental pressures that "select" traits for survival .

The essential components for Darwin's theory are that the environment "selects" organisms with some traits to survive while others die out, what this means is that those who survive are best "fit" for their environments.

Other often present Darwin as saying that "survival of the fittest" means those who can be more competitive with their neighbours and are more fit (aggressive or otherwise) than their competitors.

Others, such as Richard Dawkins on Natural Selection (part 2) discusses the "Selfish Gene" whereby we are seen as prisoners of our genes, they (our genes) work to selfishly replicate themselves and and our behaviour is merely at the service of our genes.

Dawkins also describes the importance of the social transmission of ideas that enhance adaptation which he called memes.

Hence survival of the fittest mean the genes' fitness, not the body's

As such, altruism or pro-social behaviour is merely in appearance when our genes are acting in self-interest since we tend to share the same genes with those around us.

An Evolutionary approach to mate selection
Many socio-biologists expect males and females to behave differently due to biological (genetic) factors based upon evidence indicating that men think more often about sex, have more partners, report more use of porn)

(Buss, 1995) suggests that males prefer attractive physical features, women who are young and fertile.

Females prefer healthy but wealthy, mature, dominant males who can support and protect with a long term investment. Study done across 37 countries. Fig. 3.2

Not falsifiable but based upon speculations and guess work.
Verification of hypothesized "causes" is done to confirm theory.  

Makes use of stereotypes and masculine bias

Socialization is actual cause of similarities and apparent universal preferences

Standards within a society change and across them too, with contact

Sample may not be getting people "off the beaten track"
  Elsewhere Buss discusses on
you tube how men and women have conflict with each other, due to genetics



Family Studies of Inheritance

Heritability is a statistic of estimation regarding the proportion of variability for traits that is attributable to genetic differences within a given population. It applies to groups only and does not discount the influence of environmental determinants.
(groups vary in heritability-enriched vs. impoverished).  

Myers contends that evolutionary history predisposes us to altruism and aggression and that Genes + Experience lead to personality, emotions, intelligence. We are the products of both nature and nurture together.

Ethical questions arise when considering the human genome project in terms of selecting babies based upon DNA sequences and giving people insurance or jobs based upon their genetic liabilities. Eugenics is part of our past.

Group differences have been proposed and challenged for intelligence, ...

Twin Studies
Monozygotic (Mz ) and Dizygotic (Dz ) twins
are examined for the concordance of traits and characteristics. Essentially this is a correlation of traits examined through survey or psychological tests.

Mz twins share 100% of their genes while Dz twins share on average 50% of their genes, same for siblings and parents or children.

Studies suggest that some traits such as extroversion and neuroticism have higher concordance rates for Mz than Dz twins. Propensity for divorce?

Schizophrenia and other mental disorders are often more likely to be found in both twins if one has the disorder

Separated twins: Naturalistic quasi experiment where Mz twins are separated at birth and reunited in adulthood.
E.g., Jim and Jim , Oskar and Jack or Gerald & Mark.

(Jim & Jim -each married a woman named Linda, divorce them and then married women named betty, named their sons James Alan and James Allan, both named their boy-hood dogs "toy" they drank the same brand of beer and chain-smoked the same brand of cigarettes, both were deputy sheriffs and worked at McDonalds and pumped gas, enjoyed woodworking and stock-car races, chewed their finger nails and vacationed on the same Florida beach.) 

-Any two people will have chance similarities (chance)
-Twins adopted to similar homes by common agency (environment)
-had been together after reunion prior to testing


Now that all of this has been said there is  the newly developing field of epigenetics.

Epigenetics is a field that suggests that the environments of our parents or ancestors has an impact on us!

This is reflective of the Theory of Acquired Inheritance put forth by Jean-Baptiste Lamarck (1744-1829) ( a theory that people have said was falsified for many years now)!

Additionally the "New Biology" of Bruce Lipton (4) indicates that biology and perception (of the environment) are very closely related in terms of  how "perception"( or beliefs) changes biology. See also parts 5,  6 & 7 (implications to cognition and health).

We adjust our genes to fit the environments that we live in (based on perception)!

 He also discusses how "nature" can also be impacted by "mind" in Beyond Darwin



Part II From Nature to Nurture

Adoption Studies

appears to be more similar to biological than adopted parents, but values attitudes, manners, faith and politics are more similar to adopted parents (Wade et al. 2007).

Emotional reactivity is similar across ages (0-9mo);
as is inhibited or social type (4 mo - 2 yr);
emotional intensity (4 -12 mo, 3-21 yr).

Comparative studies with monkeys show heredity predisposes temperament.

Walter Mischel (2004) and socio-cognitive approach: looking at how behaviour is a result of persons and situations.  We interpret personality or people's behaviours against how we think certain situations should go. 

Zimbardo (2008) discusses Mischel's work on delay of gratification in young children (age 4) and predicts how they will respond to later issues in life based upon their style of time perspective. youtube

In the Time paradox, Zimbardo considers how present (hedonism) and future (delay) style lead to differences in education, taking drugs, etc.  [listen on line in d2l  (or CourseSpaces) to the time paradox lecture]


Experience and Brain Development

Rosenzwig & Krech raised rats in a variety of environments and found those in solitary vs. communal settings had a significant difference in their brain thickness and mass.


Culture & Self

Culture can be defined as involving language, history, values, norms, social organization and religious or cosmological views of nature, reality and self.

Looking at the anthropology of selves it is clear that there are as many models of self as their are indigenous psychologies.

Many cross-cultural psychologists look for broad similarities and differences in notions of self and other psychological characteristics where it is understood that culture creates or has a significant impact on the development of "selves" WAI

Triandis (1989) discusses individualism and collectivism (see table 4.1) which demarcates two broad forms of culture and their impacts on notions of self.

Markus and Kitayama (1991) Cultural Self Schematta
- Cognitive templates that organise our cognitive, affective, and motivational elements of who we are, and are caused by having lived in particular cultures.

-Primary features of these are interdependent self and independent self.
-most general and over arching of an individual's self system.
(note computer metaphor)

 Interdependent self involves: seeing oneself as part of a social group
-tend to have more complete integration of contextual and personal
-tend to feel other -focused 'social emotions' e.g, guilt, pride, shame 

 Independent self involves: bounded, unique motivational and cognitive
centre of awareness who make more self-references and feel ego-focused emotions e.g., joy sadness, anger, fear, ...

These differences are even seen in our brains where we expereince a sense of self and mother Zhu, et al. (2007).