Saturday 24 May 2008

Selective abortion in nature

A Danish researcher proposes an incredibly intriguing hypothesis - that the sex of the progeny is related to the stress levels experienced by the expecting mother during her pregnancy. Based on data collected from surveys that were administered to nearly 8000 expecting mothers between 1989 and 1992, the researcher arrived at a startling correlation- the more stressed a mother had been, the less chance she had of having given birth to a boy.

Most of us are statisticians enough to appreciate that correlation does not imply causality. However, the goal of scientific investigation is to look at possible causal structures that manifest themselves through final correlation. The investigator believes that if at all there is such a causal mechanism that directs the sex of the baby according to the stress experienced by its mother, the reasons are likely to be adaptive rather than pathological.

But all said and done, in spite of being a Darwinist at heart (not a social one though), I cannot say I am not surprised (even amused to an extent) when I read paragraphs such as these:

That is because the chances are that a daughter who reaches adulthood will find a mate and thus produce grandchildren. A son is a different matter. Healthy, strapping sons are likely to produce lots of grandchildren, by several women—or would have done in the hunter-gatherer societies in which most human evolution took place. Weak ones would be marginalized and maybe even killed in the cut and thrust of male competition. If a mother's stress adversely affects the development of her fetus (as it is likely to do) then selectively aborting boys, rather than wasting time and resources on bringing them to term, would make evolutionary sense. That, in turn, would explain why women in rich countries, who are less likely to suffer from hunger and disease, are more likely to give birth to sons.

- From The Economist
In so much as the contextual premises that such arguments are based upon, they seem perfectly reasonable. But there is still a part of me that feels something clinically lacking in these reasonings. A lazy disposition holds me back from thinking further in the present moment, so I'll leave it for the record.

3 comments:

Anirudh Patil said...

hmm..
i had read a few days back that the sex of the child depends on the nourishment the mother gets during her pregnancy. I think the result was better the nourishment, higher the chances of having a boy. When a doctor from delhi was asked what are we supposed to make out of this, she replied, "such studies must be taken with a pinch of salt".

Aytidaa Madras said...

It sounds like sense but feels like nonsense. Ever heard an argument that makes you feel like that?

Karthik Shekhar said...

@adidas- Very much. I can understand what you're feeling. I felt the same way when I learned of the 'principle of least action' in Physics. More than the feeling of 'nonsense', I was astounded as to why something like this should be true. But it does make for a brilliantly economical understanding of mechanics, I thought later.

If you could see the theory of the 'selfish gene' by Richard Dawkins in a similar vein, I guess what is mentioned in the news item might seem a little more plausible