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Evolutionary
Psychology: The 'Emperor Eugenics' in new clothes? Author Paul Kenyon
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Visit the SALMON Bookshop for recommended books on this topic |
Evolutionary psychology views much of human behaviour as the product of evolutionary forces which shaped the survival and reproductive success of our ancestors. It challenges the dominant view within psychology that the human mind is blank at birth, and is filled as the result of experiences during the individual's lifetime.
Evolutionary psychology has been accused of resurrecting biological determinism; of supporting the view that our behaviour is written in our genes.
Biological determinism has a dark history - born as social darwinism and let loose on the world as eugenics which sought to increase desirable characteristics in the human population by selective breeding. Eugenic's methods included: cutting off your head or your balls!
This lecture will argue that there is a fundamental difference between the 'biological determinism' of eugenics and evolutionary psychology.
The lecture also introduces two apparent weaknesses in contemporary evolutionary psychology:
The lecture ends by suggesting that the application of Tinbergen's four questions about behaviour: 'How has it evolved?',' How does it develop?' 'What are its immediate causes?' and 'What is its function?', may rid evolutionary psychology of the charge of crude biological determinism.
The birth of evolutionary psychology
Jefferson's introduction to the American Declaration of Independence begins with these famous words:
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| First Page of Jefferson's Draft of the Declaration of Independence |
Until relatively recently psychology was dominated by the Standard Social Science Model which echoes the belief that we are all equal at birth. According to this model the human mind is blank at birth (a tabula rasa - blank slate) and is filled as the result of experiences during the individual's lifetime. Behaviourism is a classic example of this approach to understanding human behaviour.
The father
of behaviourism, John Watson, made this startling
claim about human nature in 1924:
"give me a dozen healthy infants, well -formed, and my own specified world to bring them up in and I'll guarantee to take anyone at random and train them to become any type of specialist I might select - doctor, lawyer, artist, merchant-chief, and, yes, even beggar man and thief , regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors" Watson was exaggerating and he knew it, because he added:
"I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years"
(see Boakes, 1984, pp226)
In
his recent book "The Blank Slate: The Modern Denial of Human Nature",
Steven Pinker (2002) points out
the social impact of the view that humans are born as blank slates:
"The Blank Slate has also served as a sacred scripture for political and ethical beliefs. According to the doctrine, any differences we see among races, ethnic groups, sexes, and individuals come not from differences in their innate constitution but from differences in their experiences. Change the experiences—by reforming parenting, education, the media, and social rewards— and you can change the person. Underachievement, poverty, and antisocial behavior can be ameliorated; indeed, it is irresponsible not to do so." Steven Pinker discusses his book "The Blank Slate: The Modern Denial of Human Nature" in this video (authors@MIT 2002)
In the 1960s
and 1970s most psychologists came to accept that
behaviour develops as an interaction between
factors in an animal's environment, as well as
biological predispositions.
In 1975
E.O. Wilson wrote a groundbreaking and challenging book 'Sociobiology
the New Synthesis' in which he argued that human social
behaviour could be explained in evolutionary terms. The term
sociobiology has now been replaced by the phrase 'evolutionary
psychology'. A good place to begin reading about this new
area is Cosmides and Tooby "Evolutionary Psychology: A Primer" which is
available online.
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According to
evolutionary psychology, human behaviour has evolved,
it is adapted to meet the survival and
reproductive challenges faced by our ancestors, and it is controlled by
modular structures whose operation
is unconscious.
Evolutionary psychologists are particularly interested in psychological mechanisms that:
Evolutionary psychologists believe that behaviour is strongly influenced by inherited factors, and that every human being acts (consciously, but mostly unconsciously) to enhance their inclusive fitness - i.e. to increase the frequency and distribution of their genes in future generations. As Steven Pinker puts it, 'the ultimate goal that the mind was designed to attain is maximizing the number of copies of the genes that created it'. |
The debate between The Standard Social Science Model and evolutionary psychology boils down to whether fundamental aspects of the mind are constructed during development of the individual, or have evolved during development of the species.
Evolutionary psychology is controversial
Evolutionary psychology is controversial; it confronts the standard social science model and it has generated socio-political debate in the wider community. Some of this criticism is well-founded, but some is based on misunderstanding.
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Evolutionary psychology ...
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The benefits of evolutionary psychology
Let me put this
crudely, starkly and provocatively
- the scientific study of human behaviour is fragmented into several
virtually independent subdisciplines. Some of these subdisciplines have
ignored 150 years of scientific research which flowed from Darwin's
theory of evolution.
Why does contemporary psychology ignore Darwin? Because psychology got badly burnt when it flirted with social darwinism - a popular misrepresentation of Darwin's theory of evolution through natural selection - in the guise of eugenics. And as we shall see shortly some research into human behaviour is still exploited by modern advocates of eugenics. |
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Four evolutionary processes in a nutshell
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Natural
selection
Sexual selection The peacock fascinated Darwin: How could natural selection alone have led to such an elaborate plumage? Surely such an encumbrance would have jeopardized the bird's survival? He proposed that secondary sexual characteristics of male animals evolved because females preferred to mate with individuals that had those features. In essence, sexual selection can operate through two mechanisms:
Parental investment Darwin's (1871) theory of sexual selection was developed further by Trivers (1972) who argued that because of parental investment, the sex that invests greater resources in offspring will evolve to be the choosier sex in selecting a mate. In contrast, the sex that invests fewer resources in offspring will evolve to be more competitive with its own sex for access to the high-investing sex. Hamilton's kin selection theory The existence of altruism posed a significant challenge to Darwin's theory of evolution through natural and sexual selection. For example:
Hamilton proposed that genes can spread by benefiting other carriers of the same gene. This additional mechanism underlying evolution is called inclusive fitness or kin selection theory.
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Abuses of evolutionary theory
The use of evolutionary principles to explain human behaviour - Social Darwinism - was championed by the British philosopher Herbert Spencer who coined the phrase 'survival of the fittest' which implies that only the ruthless will survive.
gives this summary of his views:
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progress in society was to be achieved by a 'genuine liberalism' which
maximized individual liberty and minimized interference from the State;
vaccination, and care for the infirm or insane, only served to promote
the regression of the human race; economic and social differences
between races, sexes or classes were part of the natural order, a
necessary part of evolution."
(Boakes, 1984; emphasis added) |
Eugenics and selective breeding
The term eugenics refers to a set of methods that are designed to increase desirable characteristics in the human population by selective breeding. For example, individuals with desirable characteristics are encouraged to have children, whilst those with undesirable characteristics are sterilized.
| This form is an Order for Sexual
Sterilization of an inmate in a state hospital in Virginia
(USA).
If "the Board finds that the said inmate is [either] insane, idiotic, imbecile, feeble-minded [or] epileptic and by the laws of heredity is the probable potential parent of socially inadequate offsprings likewise afflicted; that the said inmate may be sexually sterilized without detriment to his/her general health, and that the welfare of the inmate and of society will be improved by such sterilization." [emphasis added] The 'inmate' would be sterilized 30 days after the form was signed. |
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Where did the terms 'idiotic' and 'imbecile' come from? - psychology!
Intelligence tests - a potential eugenic tool?
As
psychologists you will be familiar with the use of intelligence tests
to reveal individual differences. IQ tests were
invented by the French psychologist
Alfred Binet in 1905 to select children for
academic or vocational schools. There are echoes of this approach to
education in the British system of grammar and secondary modern schools
which have only relatively recently been replaced by comprehensive
schools by most local educational authorities.
IQ scores range from 0 to 200 and fit a bell-shaped curve, with an average IQ of 100. Normal intelligence ranges from 86 to 115. At one time, terms like "moron," "imbecile," and "idiot" described persons with IQs below 86, while "bright" and "genius" were used for scores above 115.
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You are probably aware of the controversy surrounding the British psychologist Burt's research into intelligence. Burt claimed that IQ was 80% inherited and 20% environmentally determined. This breakdown of IQ into a small contribution from nurture but a large contribution from nature could be used to justify the belief that intelligence was to a large extent fixed at birth, biologically determined and essentially immutable.
Subsequent analysis of his papers indicates that Burt fabricated some of his most important data (see Hearnshaw, 1979).
Eugenicists employed IQ and other tests to
compare different racial and ethnic groups. In the 1920's
some American psychologists (who were mostly WASPs - White Anglo Saxon
Protestants) attempted to use the results of IQ tests to influence
congress which was debating the introduction of legislation to restrict
immigration from southern and eastern Europe. This
attempt to use psychology to influence legislation was opposed by
scientists who had suffered from racial discrimination on account of
their 'non-Aryan' background. But the influence of social darwinism and
eugenics persisted - and had horrific consequences - in Europe during
the second world war when millions of people were murdered on account
of their 'race', behaviour or beliefs.
Revulsion at the consequences of eugenics probably influenced psychologists to embrace behaviourism and the Standard Social Science Model. The message that the human mind is blank at birth (a tabula rasa - blank slate) and is filled as the result of experiences during the individual's lifetime was consistent with the social and political climate in democracies after World War II.
But the view that aspects of human behaviour were genetically determined keeps resurfacing. In 1994 Herrnstein and Murray published the controversial (see Bouchard and Dorfman, 1995) book "The Bell Curve" which discussed the relationship between IQ and socioeconomic status. Herrnstein and Murray argue that:
In an interview Dr. Robert Gordon of Johns Hopkins University stated in response to the question "Do you think that people with low IQs should be paid to be sterilized?" replied:
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Apart from the condescending, patronizing tone of the answer, Gordon gives a clear cut example of how genetics and psychological research can be misused to advocate a social policy based on eugenics.
Herrnstein and Murray met with a hail of criticism including the generally accepted views that
Nevertheless
IQ and the social environment do interact in important ways. For
example, in a review of Herrnstein and
Murray book "The Bell Curve" Bouchard commented:
I think Bouchard may be implying that an apparently environmental factor - marriage - is more important than a genetic factor - IQ - in determining whether or not a child will be raised in poverty. But, as we shall see, evolutionary explanations of marriage (long and short term mating strategies) and child care (parental investment) lie at the heart of evolutionary psychology. |
Although
evolutionary psychology has made a number of useful contributions to
our understanding of reproductive and parental behaviours, this is
potentially controversial territory. In the 1930s
eugenics was also concerned with these topics as shown on the cover of
this book which discusses:
For this reason evolutionary psychologists enter these waters with extreme caution. |
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Is evolutionary psychology eugenics in new clothes?
Evolutionary psychology may have attracted criticism and suspicion from some psychologists because it appears to resurrect old issues to do with eugenics and genetic determinism in a new suit of clothes. However eugenics is concerned about the differences between people and about placing value judements on those differences. Evolutionary psychology is concerned with universals - behaviours that are common to all humans across all cultures.
Biology has taken massive strides during the last 50 years:
Chromosomes
are found in the nuclei of most cells in the body (see Patterson,1999).
Chromosomes are made of DNA (deoxyribonucleic acid). DNA consists of
four different bases: adenine, cytosine, guanine and thymine. In 1953
Watson and Crick worked out the structure of DNA - the double-helix.
DNA is like a spiral staircase. The side pieces consist of long chains
of sugar and phosphate. The 'treads' of the staircase are made of two
interlocking bases. But there are only two types of tread because the
four bases can only pair in two ways:
This staircase of interlocking bases is called the 'genetic code' or genome. Humans have 24 distinct chromosomes (separate staircases). Each chromosome consists of 50 million to 250 million base pairs. Sections of chromosome are called genes. Genes make up only 2% of the human genome. Humans contain 30 to 100 thousand genes (Kreek in Yudell and DeSalle, 2002, p97). Each cell of the body (apart from red blood cells) contains a complete copy of the genome. |
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The human genome project
has unravelled the staircase of interlocking bases in order to read the
genetic code (See Yudell and DeSalle 2002).
There are 3 million base pair differences in the DNA of any two randomly selected individuals. To put this in perspective a bacteria or virus has only 3 million base pairs. |
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Genes control the production of proteins by cells in the body. Proteins are large complex molecules made up of chains of amino acids. Within a gene each specific sequence of three bases controls the addition of one amino acid to the growing protein chain.
By
clicking on these links you can view slides in the display area which
show:
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| Images
created by the U.S. Department of Energy Human Genome Program's Human
Genome Management Information System (HGMIS) presented here by courtesy of the U.S. Department of Energy Human Genome Program or U.S. Department of Energy Genomes to Life Program see website at http://www.ornl.gov/hgmis. |
The genotype describes the genes inherited by an organism. Phenotype refers to an individual's anatomical structure, physiology and behaviour. The phenotype refers to everything that can be easily observed and measured about an plant, animal or human being.
Our phenotype is the product of
I deliberately used the word 'our' in the phrase "Our phenotype is the product of " because as psychologists we are interested in human behaviour. But debates about human phenotype are based on the science of genetics. A quick glance through a genetics textbook (e.g. Suzuki et al, 1981) reveals that genetics is founded on the study of plants and simpler animals such as the fruit fly Drosophila. The next section gives a flavour of these studies (see Lewontin (2000) Chapter 1 ).
It is relatively easy to study how the same genotype reacts to different environments in plants.
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Some species of plant can be cut into several pieces that will grow if they are put into soil. In this experiment (Clausen et al. 1958 see Suzuki et al, 1981 p18) seven Achillea plants were each cut into three separate sections.
The three plants in each column have identical genotypes. Each parent plant (#4.....#16) has a unique genotype.
Consider the plants that resulted from parent plant #4. The clones grew well at low and high altitude, but at medium elevation this genotype failed to thrive.
Maybe the conditions are not suitable for growing Achillea at 1400 meters. But this explanation is not likely because the cutting from parent #24 thrived at this level compared to the performance of this genotype at low and high altitude.
What does this experiment tell us about genotype. Quite clearly the phenotype of each cloned plant depends on the environment in which it grows.
Also it is impossible to make any firm conclusions about altitude as an environmental factor in this study. For example, some of the plants grew well at the intermediate site (#23,24) where others fared less well (#4,16).
This graph is based on
the data presented in the picture above. Individual lines on the graph
shows how the three cuttings taken from one plant grew at various
altitudes. Each line is called the 'norm of reaction'
.The term 'norm of reaction' refers to how a particular genotype (from
a parent plant) develops into a phenotype (cloned offspring) as a
function of the environment in which the clone develops.
It is immediately obvious that identical genetic material produces different phenotypes.
This result is not peculiar to plants. Similar results have been seen in the fruit fly (see Lewontin, 2000)
Suzuki et al (1981) draw the following conclusion from this type of experiment:
Can you identify examples on the graph that illustrate these point?
What is the consequence
of 'norms of reaction' for human behaviour? Imagine that a political
proposed a perfectly plausible proposal to modify the environment to
improve childrens' intelligence. Would it work? Well it might, but
again it might not if intelligence is the product of each child's genes
and environment.
I have used the norms of reaction from the Achillea experiment in this diagram.
The child with a genotype represented by the red line would benefit from the 'enriched' and 'hyper-enriched' environments. But the other child would suffer a progressive loss in IQ score if raised outside the normal environment.
The point of this example is not to suggest that we should abandon attempts to improve our childrens' environment, but to suggest that we need to be aware that outcomes may not always be as expected.
Incidentally the phenotypes in his hypothetical example have been given very high IQs in order to turn-up the 'ethical screws'.
The evidence presented thus far suggests that the way we are and what we do, our physical appearance and behaviour - our phenotype - is the result of a complex interaction between our genome, our environment and 'je ne sais quoi' - random factors. It is thankfully uncontrollable and unpredictable. But there may be things about ourselves that are a result of where we came from - our evolutionary past.
The application of evolutionary concepts to human behaviour
Hamilton's kin selection theory
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We have seen that kin share many common genes. Genes can spread by benefiting other carriers of the same gene. Hamilton proposed the inclusive fitness or kin selection theory to explain altruism or self-sacrifice.
In an altruistic encounter there is:
The probability that the altruist and the recipient share a gene is called the coefficient of relatedness ( r ). The diagram shows the extent to which we share genes with our relatives. The value of r varies between 0 and 1. On average we share half of our genes with our brothers, sisters and children ( r=0.5 ), and a quarter of our genes are identical with those of our grandchildren, nephews and nieces ( r=0.25 )
According to Hamilton's Rule altruism pays off if rb>c . In other words, shared genes will profit if the cost to the altruist is less than the benefit to the recipient multiplied by the probability that the recipient shares genes with the donor.
Costs and benefits are expressed in units of fitness or reproductive success with values between 0 and 1.
For the sake of argument assume you have spare food that you could give to your brother to feed him and his children.
We can test if your altruism would benefit kin selection by putting these values into Hamilton's Rule rb>c where:
You might wonder why b and c are not always equal. Why not use the spare food you have to increase your own reproductive success? Well there is a limit to how much you can eat. If you have an abundance of food and your brother is starving, the cost to you of sharing is small, but it may be a matter of life or death to your brother and his children.
Kin selection theory in action
You may not have a  twin (r = 1.0), but you
probably feel more related to
Redrawn from Study 1: Burnstein, et al (1994). |
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| Burnstein et al (1994)
and Petrinovich et al (1993) asked people to imagine how they would
react in life-and-death situations in which they could prevent the
death of a relative.
For example imagine that a train is running out of control down a track that branches. You are in charge of the points at a track junction. If the train goes down the left track it will kill one of your relatives. If you send the train down the other track it will kill two strangers. The choice is yours! |
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| The results reflect what you may have predicted; we are more likely to help a near relative (e.g. brother or sister (r=0.50) than a stranger (r=0.00) in a life-and-death situation. | |
Individuals can ensure the survival of a proportion of their genes by reproducing and helping their relatives to reproduce.
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Mateo
(2002) studied the ability of Belding's ground squirrels
to discriminate between close relatives on the basis of odours produced
by facial scent glands. Ground squirrels live in burrows. Mateo placed
odour-impregnated cubes at burrow entrances. She measured the amount of
time emerging squirrel spent sniffing these cubes. Her results show
that a Belding's ground squirrel is able to recognize as kin a relative
it has never encountered before.
This
discrimination is exquisitely sensitive; squirrels are able to
distinguish between relatives where the difference in coefficients of
relatedness is very small [ e.g. 'r' =0.06; Mateo, 2002, Figure 2b].
See Segelken (2002) for Cornell's press release on this research. |
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| Belding's ground squirrel mother and offspring picture credit: J. Mateo/Cornell University |
I have a problem with the application of kin selection to explain human behaviour. Compared to animals (see Pfennig, 2002 ), humans seem to be very poor at 'kin recognition'. The human language contains surprisingly few words to describe people that are genetically related to us. For example:
I call this the 'cricket field' problem because our language is so rich when it comes to describing the location of people on a cricket field. apparently there are at least 23 named positions that a fielder can occupy during a cricket match.
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We have no 'innate / unconscious' way of recognizing relatives. For example, at family gatherings I have to be introduced to distant relatives.
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Darwin's (1871) theory of sexual selection was developed further by Trivers (1972) who argued that because of parental investment, the sex that invests greater resources in offspring will evolve to be the choosier sex in selecting a mate. In contrast, the sex that invests fewer resources in offspring will evolve to be more competitive with its own sex for access to the high-investing sex.
Buss (1999 p 41) provides a clear description of why evolutionary psychologists have applied Trivers' theory of parental investment to human mating:
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"Barkus is willing, but Peggoty is shy" with apologies to Charles Dickens author of 'David Copperfield'
| Evolutionary psychology suggests that males have evolved an approach to mating that leads them to seek multiple copulatory partners. This prediction - based on Trivers' theory of parental investment - is consistent with the following observations: | |
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| A note of caution; These results are based on what men and women say about their desires and preferences. People's replies to questions about what they think they would do should be treated with caution. Researchers need to be wary of demand characteristics influencing participants' behaviour. Demand characteristics refer to participants awareness of experimenters' goals or cultural expectations influencing participants responses. | ||
Short-term mating: "A dance between the sexes?"
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Although the data (Buss
& Schmidt, 1993) suggest
that - compared to females - males would like to mate with more
partners over time, it does not support
the hypothesis that females are exclusively monogamous.
If you look carefully at the graph you will see that females would like
more than one partner over their lifetime. This opens up the
possibility that a male may be cuckolded
and consequently waste his parental investment.
Also examination of these results suggests that whereas:
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It is often claimed by
evolutionary psychologists that the cost of mating for men are
relatively slight. For example: "A man in human evolutionary history
could walk away from a casual coupling having lost only a few hours or
even a few minutes." (Buss, 1999, p102). But the interview data
suggests that men may have to invest between three and six months in
courtship behaviours before they get the opportunity to mate. Whilst
this is much less than the nine months a woman devotes to pregnancy
plus the years of postnatal care, there is nevertheless a greater cost
to the male than is sometimes implied. The pre-mating costs for men
seem to have been discounted by evolutionary psychology.
A small,
but significant, proportion of women in long-term relationships engage
in short-term matings (see figure). There must have been some selective
advantage for women to engage in short-term mating otherwise the
inclination to engage in this behaviour would never have had a
selection advantage for women. Buss (1999)
distinguishes between different types of explanations for female
short-term mating that have some experimental support in the human and
animal literature:
To
sum up, I would suggest that the notion of monogamous
females and polygamous males is a myth. I would suggest
that there is more symmetry in the costs and
benefits of short-term mating for both sexes than hitherto
acknowledged. It would advantage the inclusive fitness of both males
and females to engage in short-term mating where the partner offers
'good biology', and any offspring would be sufficiently resourced to
ensure their survival to reproductive age. Thus:
This analysis suggests the following hypotheses about the attitudes of genetic relatives to short-term mating:
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The historical novel 'The Other Boleyn Girl' by Philippa Gregory - the subject of a recent BBC TV programme - deals with the relationship between Mary Boleyn and Henry VIII . At a time when Henry was married to Catherine of Aragon and Mary Boleyn was married to William Carey, her father and brother (Thomas and George Boleyn) persuaded Mary, against her wishes, to enter a sexual relationship with the king - Henry VIII - to secure the Boleyn family's position at court. After the birth of a son, Henry broke off his relationship with Mary, established a new relationship with her sister Anne, divorced his wife Catherine and married Anne Boleyn. Anne failed to produce a male heir and was executed on charges of participating in extra-marital sexual relationships. Henry VIII married Jane Seymour and Mary Boleyn lived in relative obscurity with William Stafford, whom she married after the death of her first husband. |  |
Long-term mating:"A battle between the sexes"?
In a groundbreaking study of long-term mating strategies involving 10,047 participants from 33 countries Buss (1989) showed that:
Males
prefer young, physically attractive,
and chaste mates. 
Females
place greater emphasis on the earning capacity
and ambitiousness-industriousness of
potential partners than men do. It is interesting that the commentary elicited by this paper focussed on alternative explanations involving economic powerlessness for the female preferences. The findings on male desires did not provoke a spate of alternative explanations based on cultural interpretations to challenge the evolutionary explanation. Buss (1989) and Buss' responses to peer commentaries are both available online
According to conventional evolutionary psychology (e.g. Buss, 1996) these psychological differences between the sexes evolved because the adaptive problems posed by reproduction are different for men and women. However, if we examine the adaptive problems posed by long-term mating there is remarkable symmetry between the problems faced by the sexes:
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Four ways of looking at behaviour
One way of thinking about behavioural questions is to consider how they relate to stages on a species' journey through time, from the distant past into the future.
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Webcasts
--Online Audio and Video Files
about Genetics and the Human Genome Project
Humans and other mammals have approximately 3 billion
base pairs in their DNA. 
(r = 0.5) than to 
(r = 0.25) or 
(r = 0.125) or
(r = 0.00)
