Evolutionary explanation of gender

produces gendered behaviour Selective pressures on males and females Our biological sex produces gendered behaviour What is the driving force behind it? Selective pressures on males and females When discussing the evolutionary explanation make sure you first explain the link with survival. Gender differences have evolved because they are advantageous to both sexes

Males produce lots of sperms and Mate choice: because reproduction makes different demands on men and women, they adopt different strategies to choose mates. Males produce lots of sperms and can fertilise many females at little cost Females produce few large eggs once a month so they have only 300 opportunities to reproduce in their lifetime Males cannot be sure of paternity Best strategy to enhance the chances of reproducing their genes into the next generation Careful mate selection, monogamy, high parental investment Best strategy to enhance the chances of reproducing their genes into the next generation is to have sex with as many fertile females as possible. Females select males displaying genetic fitness. Like strength, status and resources Physical aggressiveness to compete with other men

Buss (1989) Aim: to investigate if evolutionary explanations for sex differences in human mate preferences are found in all cultures. (if the same behaviours are found across cultures it suggests that they could have an evolutionary basis) Sample: 37 samples from 33 countries, located on six continents and five islands, number of participants 10,047. mean age:23.05 years Buss developed a questionnaire in which the participants were asked to rate 18 characteristics i.e. good financial prospects, good looks and ambition and industriousness. Results: In most cultures: “Good financial prospects”: was rated higher by females than males “Good looks” – All of the 37 samples showed that males rated “good looks” in their mate more than females did. “ Ambition and industriousness” In 34 of the 37 samples, females expressed a higher valuation for “ambition and industriousness” in a mate than did males. Conclusions:   Buss concluded that sex differences involving mate preferences for earning potential, relative youth and physical attractiveness were strongly confirmed across cultures. Buss’s findings support evolutionary explanations of human behaviour; specifically that mating behaviour should differ according to gender, reflecting the differences in reproductive capacities of males and females. 

However ... The sample size in some countries were small, only 28 men and 27 women represented Iran. Generalisations about mate preference can’t be made from this small a sample. A questionnaire may not be a valid measure of how we select mates, for example older males do not always seek younger females, so asking people about their mate choice is different to measuring how they behave in real life situations. Schmitt (2003) did a large cross-cultural study and tested 16,288 participants from 53 countries. In each culture there was a significant difference between women’s and men’s preferences for variety in mates. In every case, males desired a larger number of mates. This is consistent with evolutionary theory, as males with low parental investment can afford to have sex with a range of women whilst females are much choosier.

Furthermore ... Thornhill & Palmer (2000) suggest rape has evolved as a mechanism for sexually unsuccessful men to pass on their genes, a number of other species use forced sex as a reproductive strategy. Ethics: the evolutionary theory justifies rape and other sexual crimes and argues that they are inevitable. The evolutionary explanation predicts that men would object investing time and resources in a child who is not genetically related, however this does not seem to be supported by reality where men become step-fathers or adopt children.

Waynforth & Dunbar (1995) Content analysis of personal ads Findings: Age Males asked for Females 1-12yrs younger than them; Females asked for Males 2-7yrs older Attractiveness Males mentioned own attractiveness 1.4 time less than Females but asked for attractiveness twice as often Resources Males mentioned own wealth 1.7 time more than Females; Females asked for wealth 4.5 times more than Males

The Hunter Hypothesis The hunter-gatherer hypothesis, Silverman and Eals (1992), was proposed as an evolutionary explanation for sex differences in spatial ability. According to this hypothesis, gender differences in task performance have arisen from a process of natural selection that favoured hunting-related skills in men and gathering–related skills in women. One of these skills is spatial ability. This hypothesis cannot be tested directly, but we can test its predictions. Many studies support this hypothesis however Hoffman (2011) found that social factors influence the development of spatial skills so it could be that women are not given the opportunity to develop theses skills rather than an evolutionary cause.

They mainly carried out jobs close to home Furthermore, women need to ensure the baby survives whilst pregnant therefore invest in their pregnancy and in feeding the baby post birth Human babies are not born ‘fully formed’ because their brains are comparatively underdeveloped. A human foetus would have to undergo a gestation period of 18 to 21 months instead of nine to be born at a neurological and cognitive development stage comparable to that of a chimpanzee newborn. However the demands on the mother’s metabolism would be too great and the size of the pelvis is also a limitation to the size of babies. However in hunter-gatherer societies child care is communal with children being looked after by many adults so there is less pressure on the mother Women did provide some food e.g. growing vegetables and grains. This avoided starvation of the group when preys were scarce. They mainly carried out jobs close to home

This is speculative (there is no direct evidence) Kuhn & Stiner (2006) Neanderthals - Did not divide their labour and died out at least 30 000 years ago. Homo sapiens - Divided their labour and survived. However there is not a single cause for the Neanderthals’ extinction, change of climate is also a possibility. It has also been argued that they have been “absorbed” by the interbreeding with modern humans.

Differences in Cognitive Style (Baron-Cohen,2002) Empathising –Systemising - E-S theory. Research has shown that women are better at empathising (put themselves in shoes of others to understand how they feel)whereas men are better are systematising ((put things into sets). This gender difference may be the result of selection pressure for males, who develop better hunting strategies, and females, who focus on rearing children. But this could be the consequence rather than the cause of gender role (brain plasticity)or the effects of socialisation of each gender.

Tend and Befriend- Taylor et al (2000) Taylor  studied animals (rats and monkeys) and humans. She found gender differences in stressful situations: Women respond by- Tending (involves nurturing activities designed to protect the self and offspring that promote safety and reduce distress) and befriending (the creation and maintenance of social networks that may aid in this process). This buffers the effects of stress. Taylor who found females have raised levels of oxytocin which reduces anxiety and increased sociability. Men do not show this increase in oxytocin and respond by “fight or flight” This is supported by Ennis et al.(2001), sample: 67 college students, ages 18–21 years (33 males and 34 females). Levels of cortisol (stress hormone) were taken a week before an exam (low stress) and immediately before an exam (high stress). There was a significant increase in cortisol levels in males participants, but not in females. This shows that men respond to stressful situations by preparing to ‘fight or flight’, while women respond with developing a support network which buffers the effects of stress.

Evaluation of the evolutionary explanation of gender Deterministic It assumes that physical and psychological traits are predetermined and programmed while virtually ignoring non-genetic factors involved in human development. Even when evolutionary psychologists acknowledge the influence of the environment, they reduce its role to that of a trigger of the predetermined developmental instructions supposed to be encoded in a person's genes.  Hypotheses are difficult or impossible to test adequately. Relies on post hoc interpretations of controversial evidence (i.e. skeletons of Neanderthals at least 30 000 years old) Evolutionary psychologists tend to assume that their own current cultural context represents a universal human nature. (Have gender roles changed over time? Are they the same in different cultures?) Reductionist: does not take into account moral values and free will. According to Taylor: our biological heritage is not destiny but rather a force that "influences and interacts with social, cultural, cognitive and emotional factors."