Wednesday, August 04, 2004
Following up on this week's development theme. The conditions under which an individual female lives, in the animal kingdom, affects what sex her babies are likely to be. Those in poorer health and lower social caste tend to have girls, higher-ups tend to have boys. This has never, however, been very well established in humans (although there are some effects seen in poor women in developing countries, mostly confounded by nutrition).
An letter published in the current Biology Letters and reviewed here seems to show a trend in richer Western women. Sortof. The women reported on the sex of their first child, and how long they thought they would live. Women who gave themselves longer tended to have had boys. There may be a real effect here, but by the write-up, I don't see any reason to take it seriously. Why did they think they'd live longer? Maybe because they're healthier, wealthier, and have family history (all linked to boy babies in poor women and monkeys)? and it's a bloody major stretch to go from there to psychological effects, as the piece wants us to do.