Posted on 08/08/2007 2:47:23 PM PDT by blam
Rich mothers 'have more sons'
By Roger Highfield, Science Editor
Last Updated: 12:01am BST 08/08/2007
Rich, married and well-educated women tend to have more sons while those who are unhealthy and poorer tend to have more daughters, according to a study.
Well-off women produce more sons
Researchers studied 50 million people and found that mothers in 'good condition’ - those who were married, better educated and younger - bore more sons than mothers in 'poor condition’.
The reason, simply put, is that women are tougher than men so according to evolutionary theory women living in poorer communities are predisposed to have daughters to ensure survival of the family line because the men are more at risk of dying younger.
The research, carried out in America and published today in the Proceedings of the Royal Society also holds up a mirror to the poor health and education of black people in America, where black mothers have long born fewer boys than white mothers, who have seven more for every thousands births.
And it has a depressing implication for countries such as India and China where female infanticide occurs, since the findings suggest that these countries cannot avoid having an excess of daughters.
The ideas has proved true for a range of species, such as insects, birds, pigs, sheep, dogs, mink and deer. The study by Prof Lena Edlund and Prof Douglas Almond of Columbia Univetsity, New York, used the “largest and most detailed data set yet employed.”
She said: “We find that married, better educated and younger (advantageous from a biological perspective) mothers are more likely to bear sons.
“For instance, relative to a mother with some college education, a mother without a high school degree was approximately 0.6% less likely to bear a boy.
“Infant deaths were more male if the mother was unmarried and young.” Being married seemed to help the survival of boy babies, though this had only one third the effect of being white as opposed to black in America.
“In the case of marital status, the results are unambiguous,” they conclude. “Married mothers bore more sons and infant mortality reinforced the pattern observed at birth. That is, married mothers were not only more likely to bear sons, but marriage was also associated with reduced risk for male infants.”
The work provides powerful confirmation of an idea set out more than three decades ago by Robert Trivers, an evolutionary biologist, and Dan Willard, a mathematician, who boil life down to one factor - having as many offspring as possible and thus passing on as many genes to future generations as possible.
The “Trivers-Willard hypothesis” argues that strong healthy women tend to have sons in order to ensure her genes and family line are passed on. These sons are in turn strong and outdo other weaker male offspring to reproduce, thus ensuring survival of the fittest and of the family line.
However, weaker or poor mothers tend to have weaker sons who do not do well and are more likely to die early - earlier than women in the same society.
To ensure survival of the family line, the women tend to have daughters because they are more likely to be survive long enough to become parents themselves.
Although the results strictly apply to the United States, Prof Edlund speculated that in developing countries she would expect the effect of a bias towards girls at the bottom social strata to be more pronounced because infant mortality is up to ten times greater than seen in America.
There is much emphasis in these societies on the need for a son to carry on the family name, said Prof Edlund. “For the son to do this, he will need a partner, and in a society where everybody hankers for sons, it is the poor whose sons would not find spouses. Thus, they might be better off with a daughter - there would be no continuation of the family name, but at least of its genes.”
but gabz, we were eatin’ dirt when we had both the boys
and living in the “high rent district” when kels was born.
every family in our immediate family
contradicts this,um, study too.
It’s just plain dumb..........
What is wrong with the UK? A bunch of weirdos.
The only reason why I can think that this would happen is because wealthier women plan everything, even the day that they conceive their children. They know when they are ovulating and do it at the exact appointed time. That’s how they end up with more boys, the boy’s swim fast.
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