Friday, April 08, 2005
Sexual selection & Evolutionary psychology
I sat through a most entertaining lecture last evening in our Social Psychology class and thought I might share a few of the notes I took regarding its content.
Sexual selection
· Intersexual selection:
If members of one sex have some consensus about the qualities that are desired in members of the opposite sex, then individuals of the opposite sex who possess those qualities will be preferentially chosen as mates...naturally, those who lack the desired qualities fail to get mates
· Parental Investment:
Males & Females differ significantly on several facets of parental investment. While males can, conceivably, produce a very large number of offspring, females can produce relatively few. Additionally, when offspring are produced, male investment is less necessary than female investment. Promiscuity can be conceived of as an OK option for males, but a bad option for females. The desired characteristics in a partner are comparatively similar as males desire a mate who is youthful and healthy and females desire a mate who is resourceful and healthy. Finally, while males are far more threatened by the thought of their partner having a sexual affair, females tend to be more threatened by the thought of their partner having an emotional affair.
· From an evolutionary perspective, humans choose partners in order to maximize reproductive success (Sprecher, Sullivan, & Hatfield, 1994).
· Biological differences between men and women have led to specific mate preferences in an effort to solve adaptive problems of reproduction (Feingold, 1992; Buss & Schmitt, 1993).
Adaptive Problems for Women in Long-Term Mating:
1 Selecting a mate who is able to invest
2 Selecting a mate who is willing to invest
3 Selecting a mate who is able to physically protect self and children
4 Selecting a mate who will show good parenting skills
5 Selecting a mate who is compatible
6 Selecting a mate who is healthy
Hypothesized solution & Evolved Mate Preference:
1 Good financial prospects; social status; older; ambition; size; strength; athletic ability
2 Dependability and stability; love and commitment cues; positive interactions with kids
3 Size (height); strength; bravery; athletic ability
4 Dependability; emotional stability; kindness; positive interactions with kids
5 Similar values; similar ages; similar personalities
6 Physical attractiveness; symmetry; good health
When we begin to examine the mate preferences of women more closely and also compare them with the preferences of men, amusing results are found. In a study examining mate preferences across the intimacy spectrum (dating - sexual relations - steady dating - marriage), a positive correlation was found between good financial prospects and the intimacy spectrum for females. In other words, the financial standards to which a woman would hold her mate are less stringent when she considers whether the mate is date worthy or “marriage material.” For males, however, a slightly different trend is found. That same positive correlation is seen, although overall good financial prospects are less important to males than females, with one glaring exception: good financial prospects are of comparatively little importance when a man is deciding whether or not to engage in sexual relations with the mate.
The disparity of mate preferences regarding financial prospects appears to be a stable phenomenon and is found across cultures. Other disparities in mate preferences found across cultures pertain to social status and the desired age of a mate. Women tend to prefer a mate of high social status much more so than men and of course, while women prefer mates of a similar age (or perhaps a little older) men prefer younger women.
The effects of the menstrual cycle on mate preferences also have an interesting affect. The ovulation cycle is theoretically important because women’s chances of becoming pregnant differ dramatically across the cycle. Although women always prefer masculine-looking faces, this preference is stronger when the chance of conception is higher. Thornhill & Gangestad (1999) asked men who varied in symmetry (as it pertains to facial structure, this is a fine predictor of physical attractiveness) to wear the same T-shirts for two days without showering or wearing deodorant. The T-shirts were collected and women were asked to judge how good or bad it smelled. Women judged the T-shirts worn by more symmetrical men as smelling better…but only if they were ovulating. The skinny on this would be; if a woman were to cheat on her respective other, it’s likely to be during her ovulation cycle and with a masculine and symmetrical man with much athletic prowess.
In some ways, men look for the same qualities in a mate as women do: intelligent, kind, humorous, understanding, healthy, and similarity in terms of values, personality, and religious beliefs. However, males were confronted with a different set of adaptive mating problems than did ancestral women and as a result, they have developed a different set of mate preferences. Allow me to speak briefly about male preferences regarding physical beauty. In the US, women typically believe that men want women who are slimmer than average, but men actually prefer women who are average. Although men’s preferences for body size vary to some degree across cultures, one body shape preference is universal: a particular ratio between the size of a women’s waist and the size of her hips. The desired waist-to-hip ratio (WHR) is a very powerful predictor of female attractiveness (.70 is optimal). WHR is also an accurate indicator of both reproductive status and long-term health status.
Short-term mating strategies are very different between the sexes. Males have lower standards, less risk, can spread genes with little investment, and most males will agree to a quick sexual encounter. For females, however, while the benefits of short-term mating are less obvious, cuckolding rates (men married to unfaithful wives) are estimated to be around 15% and may be as high as 25%.
In another related study, students were asked about the minimum percentile of intelligence you would accept in considering someone for: a date, a recurring sexual partner, a one night stand, a steady dating partner, and a marriage partner. The results indicate that both sexes desire above average intelligence for a single date, but men’s criteria are considerably lower for recurring sexual partners. The differences are even more pronounced for one-night stands. Steady dating partners and marriage partners are required to have above average intelligence for both sexes. This positive relationship is similar to the one found for good financial prospects. The results of these studies suggest that females increase selectivity as the probability of pregnancy increases and males are selective for long term relationships where they commit resources. Males being less selective if given the opportunity for a low investment reproductive opportunity of course, offset this.
Lastly, in Clark & Hatfield’s study (1989), students were approached by another student of the opposite sex, who said: “I have been noticing you around campus and I find you very attractive.” This was followed by one of three invitations:
1 “Would you go out with me tonight?”
2 “Would you come over to my apartment?”
3 “Would you go to bed with me?”
Results show that about half of both sexes said “yes” to the date, roughly 10% of the women and 65% of the men agreed to go back to their apartment, and while men were even more likely to say “yes” to the sexual invitation (somewhere around 75%), not a single woman said “yes” to the sexual invitation. Also noteworthy was that, if men said “no,” they typically apologized and/or offered an excuse such as “I’m dating someone,” whereas the women were more inclined to slap the fella.
Sexual selection
· Intersexual selection:
If members of one sex have some consensus about the qualities that are desired in members of the opposite sex, then individuals of the opposite sex who possess those qualities will be preferentially chosen as mates...naturally, those who lack the desired qualities fail to get mates
· Parental Investment:
Males & Females differ significantly on several facets of parental investment. While males can, conceivably, produce a very large number of offspring, females can produce relatively few. Additionally, when offspring are produced, male investment is less necessary than female investment. Promiscuity can be conceived of as an OK option for males, but a bad option for females. The desired characteristics in a partner are comparatively similar as males desire a mate who is youthful and healthy and females desire a mate who is resourceful and healthy. Finally, while males are far more threatened by the thought of their partner having a sexual affair, females tend to be more threatened by the thought of their partner having an emotional affair.
· From an evolutionary perspective, humans choose partners in order to maximize reproductive success (Sprecher, Sullivan, & Hatfield, 1994).
· Biological differences between men and women have led to specific mate preferences in an effort to solve adaptive problems of reproduction (Feingold, 1992; Buss & Schmitt, 1993).
Adaptive Problems for Women in Long-Term Mating:
1 Selecting a mate who is able to invest
2 Selecting a mate who is willing to invest
3 Selecting a mate who is able to physically protect self and children
4 Selecting a mate who will show good parenting skills
5 Selecting a mate who is compatible
6 Selecting a mate who is healthy
Hypothesized solution & Evolved Mate Preference:
1 Good financial prospects; social status; older; ambition; size; strength; athletic ability
2 Dependability and stability; love and commitment cues; positive interactions with kids
3 Size (height); strength; bravery; athletic ability
4 Dependability; emotional stability; kindness; positive interactions with kids
5 Similar values; similar ages; similar personalities
6 Physical attractiveness; symmetry; good health
When we begin to examine the mate preferences of women more closely and also compare them with the preferences of men, amusing results are found. In a study examining mate preferences across the intimacy spectrum (dating - sexual relations - steady dating - marriage), a positive correlation was found between good financial prospects and the intimacy spectrum for females. In other words, the financial standards to which a woman would hold her mate are less stringent when she considers whether the mate is date worthy or “marriage material.” For males, however, a slightly different trend is found. That same positive correlation is seen, although overall good financial prospects are less important to males than females, with one glaring exception: good financial prospects are of comparatively little importance when a man is deciding whether or not to engage in sexual relations with the mate.
The disparity of mate preferences regarding financial prospects appears to be a stable phenomenon and is found across cultures. Other disparities in mate preferences found across cultures pertain to social status and the desired age of a mate. Women tend to prefer a mate of high social status much more so than men and of course, while women prefer mates of a similar age (or perhaps a little older) men prefer younger women.
The effects of the menstrual cycle on mate preferences also have an interesting affect. The ovulation cycle is theoretically important because women’s chances of becoming pregnant differ dramatically across the cycle. Although women always prefer masculine-looking faces, this preference is stronger when the chance of conception is higher. Thornhill & Gangestad (1999) asked men who varied in symmetry (as it pertains to facial structure, this is a fine predictor of physical attractiveness) to wear the same T-shirts for two days without showering or wearing deodorant. The T-shirts were collected and women were asked to judge how good or bad it smelled. Women judged the T-shirts worn by more symmetrical men as smelling better…but only if they were ovulating. The skinny on this would be; if a woman were to cheat on her respective other, it’s likely to be during her ovulation cycle and with a masculine and symmetrical man with much athletic prowess.
In some ways, men look for the same qualities in a mate as women do: intelligent, kind, humorous, understanding, healthy, and similarity in terms of values, personality, and religious beliefs. However, males were confronted with a different set of adaptive mating problems than did ancestral women and as a result, they have developed a different set of mate preferences. Allow me to speak briefly about male preferences regarding physical beauty. In the US, women typically believe that men want women who are slimmer than average, but men actually prefer women who are average. Although men’s preferences for body size vary to some degree across cultures, one body shape preference is universal: a particular ratio between the size of a women’s waist and the size of her hips. The desired waist-to-hip ratio (WHR) is a very powerful predictor of female attractiveness (.70 is optimal). WHR is also an accurate indicator of both reproductive status and long-term health status.
Short-term mating strategies are very different between the sexes. Males have lower standards, less risk, can spread genes with little investment, and most males will agree to a quick sexual encounter. For females, however, while the benefits of short-term mating are less obvious, cuckolding rates (men married to unfaithful wives) are estimated to be around 15% and may be as high as 25%.
In another related study, students were asked about the minimum percentile of intelligence you would accept in considering someone for: a date, a recurring sexual partner, a one night stand, a steady dating partner, and a marriage partner. The results indicate that both sexes desire above average intelligence for a single date, but men’s criteria are considerably lower for recurring sexual partners. The differences are even more pronounced for one-night stands. Steady dating partners and marriage partners are required to have above average intelligence for both sexes. This positive relationship is similar to the one found for good financial prospects. The results of these studies suggest that females increase selectivity as the probability of pregnancy increases and males are selective for long term relationships where they commit resources. Males being less selective if given the opportunity for a low investment reproductive opportunity of course, offset this.
Lastly, in Clark & Hatfield’s study (1989), students were approached by another student of the opposite sex, who said: “I have been noticing you around campus and I find you very attractive.” This was followed by one of three invitations:
1 “Would you go out with me tonight?”
2 “Would you come over to my apartment?”
3 “Would you go to bed with me?”
Results show that about half of both sexes said “yes” to the date, roughly 10% of the women and 65% of the men agreed to go back to their apartment, and while men were even more likely to say “yes” to the sexual invitation (somewhere around 75%), not a single woman said “yes” to the sexual invitation. Also noteworthy was that, if men said “no,” they typically apologized and/or offered an excuse such as “I’m dating someone,” whereas the women were more inclined to slap the fella.
