Sex ratios seem to vary by latitude
This is an interesting tidbit from the New York Times today - although more boys than girls are born all over the world, the ratio seems to be smaller among people living nearer to the equator. And no one is sure why. There are obviously many factors that influence the skewed sex ratio, but latitude is interesting because it's purely natural - it's not a cultural or economic factor like diet, selective abortion, or war.
Strangely, the researcher conducting the study found that "African countries produced the lowest sex ratios — 50.7 percent boys — and European and Asian countries had the highest with 51.4 percent.The effect of latitude persisted across wide variations in lifestyle and socioeconomic status. There were large differences in sex ratio between tropical regions within 23 degrees of the equator and the temperate regions 23 to 50 degrees north or south, but no difference between the temperate regions and the subarctic north of 50 degrees." And apparently, data that might have been changed by abortion or the killing of baby girls was excluded.
The scientists say that it may have something to do with evolution - or that it might have something to do with the quality of sperm at different temperatures. And some scientists pointed out that it's virtually impossible to tease out the effects of poverty and other conditions, so the study may be fatally flawed. But if it's true, it's an interesting puzzle - what do you think?