That's essentially what this study is saying:
http://www.telegraph.co.uk/science/science-news/9289125/Men-more-attracted-to-women-who-act-dumb.html
Makes perfect sense. Males evolved to take advantage of every sexual opportunity that presents to them. After all, unlike women, men could decide after conception whether to dedicate resources to nurturing their offspring (women were stuck being pregnant). When men do decide to commit and dedicate resources, the qualities that they seek are different.
If you are a woman interested in attracting quality men for long term commitment, it is probably helpful to still show some vulnerability (potential for easy sex) by acting receptive and playing a bit dumb. 100% prim and proper does not grab male attention. However, if you act 100% dumb, you will be treated as such.
Showing posts with label Human Biology. Show all posts
Showing posts with label Human Biology. Show all posts
Wednesday, May 30, 2012
Tuesday, May 15, 2012
Female Shortage Leads to Early Marriage for Females - and Why Polygyny Leads to Oppression of Women and Angry Men
This article from the journal of Evolutionary Psychology describes what tends to happen when there's a relative shortage of women compared to men. The authors analyzed census data from 50 largest metropolitan areas in the United States and found that the relative shortage of women was correlated with:
1. lower average age of females at marriage
2. higher variation in the ages of males at marriage (no significant effect on average age at marriage)
The explanation is essentially this: when there is a shortage of women, women get wooed into marriage more aggressively and tend to marry at a younger age. Another way of looking at it is that women are more likely to find a suitable mate at an earlier age. Since young men know that there's increased competition for brides, they are also more likely to be willing to want to commit at a young age. However, young men do not on average have the wealth and status of older men. Some women may use the extra bargaining power that they have to marry an older guy with wealth and status. Also, some young men may find themselves "unmarriageable" before building their careers. All this combines to form a situation in which women tend to marry early but males vary a lot in the age at marriage.
Some amount of female shortage in a society that enforces monogamy (USA) is clearly beneficial for women, who can use their scarcity to land either a younger guy who otherwise wouldn't have committed or an older guy with wealth and status. However, extreme female shortage caused by polygyny (one man can take on multiple wives) is bad for most women and most men. In every society where polygyny is practiced, the average age of marriage is very low. This is a uniform trend from ultra-orthodox Mormon communities, to Muslim societies, to many countries in Africa. This makes complete sense: since some men take multiple wives, there's an extreme shortage of single women compared to men looking for brides. Women get hit on aggressively and men are very willing to marry. The age at marriage becomes so low that many women forego higher education.
The need to keep multiple wives in line while keeping aggressive single men at bay promote restriction of female freedom and strong patriarchy. To varying degrees, women are restricted to the home and are forbidden from showing off their sexual appeal publicly (burqas are the extreme case, orthodox Mormons have a code of dress). Look at the two pictures below. Both types of dresses are designed to hide women's sexual appeal - it's difficult to judge the body contours of these women. There's a huge variation in male reproductive success, and the winner males must try hard to keep their spoils to themselves.
The loser males, in particlar, become very frustrated. In monogamous societies, virtually all males are guaranteed a wife if he wants one badly enough (just not as hot and high-status as he might hope). There's overwhelming evidence that when men marry, they become calmer and more stable. His testosterone goes down. It is perhaps no coincidence that Muslim societies tend to produce suicide bombers. They are men who are angry, frustrated, and have no family anyway. In almost all civilizations, monogamy was the rule - exceptions were granted only for very powerful men such as kings - and even in those cases there was usually only one official wife. All this was for a good reason, and I am lost as to why Muslim societies developed the way they did. Perhaps the promise of virgins girls in heaven kept lower status Muslim men from revolting?
1. lower average age of females at marriage
2. higher variation in the ages of males at marriage (no significant effect on average age at marriage)
The explanation is essentially this: when there is a shortage of women, women get wooed into marriage more aggressively and tend to marry at a younger age. Another way of looking at it is that women are more likely to find a suitable mate at an earlier age. Since young men know that there's increased competition for brides, they are also more likely to be willing to want to commit at a young age. However, young men do not on average have the wealth and status of older men. Some women may use the extra bargaining power that they have to marry an older guy with wealth and status. Also, some young men may find themselves "unmarriageable" before building their careers. All this combines to form a situation in which women tend to marry early but males vary a lot in the age at marriage.
Some amount of female shortage in a society that enforces monogamy (USA) is clearly beneficial for women, who can use their scarcity to land either a younger guy who otherwise wouldn't have committed or an older guy with wealth and status. However, extreme female shortage caused by polygyny (one man can take on multiple wives) is bad for most women and most men. In every society where polygyny is practiced, the average age of marriage is very low. This is a uniform trend from ultra-orthodox Mormon communities, to Muslim societies, to many countries in Africa. This makes complete sense: since some men take multiple wives, there's an extreme shortage of single women compared to men looking for brides. Women get hit on aggressively and men are very willing to marry. The age at marriage becomes so low that many women forego higher education.
The need to keep multiple wives in line while keeping aggressive single men at bay promote restriction of female freedom and strong patriarchy. To varying degrees, women are restricted to the home and are forbidden from showing off their sexual appeal publicly (burqas are the extreme case, orthodox Mormons have a code of dress). Look at the two pictures below. Both types of dresses are designed to hide women's sexual appeal - it's difficult to judge the body contours of these women. There's a huge variation in male reproductive success, and the winner males must try hard to keep their spoils to themselves.
The loser males, in particlar, become very frustrated. In monogamous societies, virtually all males are guaranteed a wife if he wants one badly enough (just not as hot and high-status as he might hope). There's overwhelming evidence that when men marry, they become calmer and more stable. His testosterone goes down. It is perhaps no coincidence that Muslim societies tend to produce suicide bombers. They are men who are angry, frustrated, and have no family anyway. In almost all civilizations, monogamy was the rule - exceptions were granted only for very powerful men such as kings - and even in those cases there was usually only one official wife. All this was for a good reason, and I am lost as to why Muslim societies developed the way they did. Perhaps the promise of virgins girls in heaven kept lower status Muslim men from revolting?
Thursday, May 10, 2012
Why are Asian women less likely to have twins?
In our cell biology class on placenta and human reproduction today, the
professor talked a bit about twinning. According to him, the rate of
monozygotic (identical) twinning is fairly constant across populations, but the
rate of dizygotic (fraternal) twinning varies considerably, depending
on maternal characteristics. In order to have dizygotic twins, a woman must at
least ovulate two eggs, at least two of which must be fertilized and be
implanted in the woman's womb. The following are true of the rate of dizygotic
twinning:
1. More likely among overweight women.
2. More likely among women in their 30s.
3. More likely among women of African ancestry, and least likely among Asians. Whites are in between. According to wikipedia, the twinning rate of the Yoruba people in Africa is 40 per thousand. That of the Japanese is 6 per thousand.
#1 makes perfect evolutionary sense. In the evolutionary environment, being overweight was a signal that nutrition is abundant. It would have been evolutionarily advantageous to have twins when food was aplenty. Similarly, overweight children tend to enter puberty at an earlier age. In contrast, severe dieting often delays puberty in teenagers and often causes women to skip an ovultion. The human body is designed to reproduce more in times of plenty, and reproduce less in times of famine.
#2 is paradoxical. I can't come up with an evolutionary justification. Could it be that women in their 30s tend to have more dizygotic twins primarily because they are more likely to use In Vitro Fertilization to become pregnant than women in their 20s? In IVF, it is a routine practice to introduce two or more fertilized eggs into the mother, because the natural failure rate for implantation onto the womb is very high (majority of fertilized embyos do not successfully implant).
#3 is partly driven by the tendency of Asians to be thinner. But there was almost certainly selection pressure against twinning in Asians and (to a lesser extent) in White people, given the humongous variation in the rate of twinning and the widespread distribution of the gap. All human populations outside of Africa descend from a small share of prehistoric humans that left Africa - our species' birthplace. In many ways, Africans are our species genetic "default." Since East Asia and Europe were relatively inhospitable, cold, dry places during the Ice Age when humans first populated them, it may have been particularly disadvantageous to attempt to care for two babies at the same time. Perhaps for the same reason, Whites and Asians hit pubterty about 2 years after people of African ancestry do.
1. More likely among overweight women.
2. More likely among women in their 30s.
3. More likely among women of African ancestry, and least likely among Asians. Whites are in between. According to wikipedia, the twinning rate of the Yoruba people in Africa is 40 per thousand. That of the Japanese is 6 per thousand.
#1 makes perfect evolutionary sense. In the evolutionary environment, being overweight was a signal that nutrition is abundant. It would have been evolutionarily advantageous to have twins when food was aplenty. Similarly, overweight children tend to enter puberty at an earlier age. In contrast, severe dieting often delays puberty in teenagers and often causes women to skip an ovultion. The human body is designed to reproduce more in times of plenty, and reproduce less in times of famine.
#2 is paradoxical. I can't come up with an evolutionary justification. Could it be that women in their 30s tend to have more dizygotic twins primarily because they are more likely to use In Vitro Fertilization to become pregnant than women in their 20s? In IVF, it is a routine practice to introduce two or more fertilized eggs into the mother, because the natural failure rate for implantation onto the womb is very high (majority of fertilized embyos do not successfully implant).
#3 is partly driven by the tendency of Asians to be thinner. But there was almost certainly selection pressure against twinning in Asians and (to a lesser extent) in White people, given the humongous variation in the rate of twinning and the widespread distribution of the gap. All human populations outside of Africa descend from a small share of prehistoric humans that left Africa - our species' birthplace. In many ways, Africans are our species genetic "default." Since East Asia and Europe were relatively inhospitable, cold, dry places during the Ice Age when humans first populated them, it may have been particularly disadvantageous to attempt to care for two babies at the same time. Perhaps for the same reason, Whites and Asians hit pubterty about 2 years after people of African ancestry do.
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