Environmentalist are always going on about how, when we as humans fiddle with one thing, there’s always an unforeseen and often negative chain reaction.

Like antibacterial soap.  Because we’re so obsessed with being clean, we’ve managed to aid in the evolution of antibacterial resistant strains.  Next step:  we invent stronger antibacterial soap, and bacteria in turn becomes resistant to that (and so on until it becomes the stuff of Dr Who episodes).

So what happens when we try to control the sex of our offspring (through, say, sex-selection abortion)?  Wouldn’t you know that we’re all wired up to keep that male to female ratio pretty much even.

When females are in short supply, they have a better chance of snagging a mate, and are thus more likely to pass the gene for fathering daughters on to their offspring. And when men are scarce, they have a better chance of mating and passing along the gene for having sons.

“It’s kind of a counterbalancing mechanism,” Gellatly explained in an interview. “You can’t get a population that becomes too skewed toward males or too skewed toward females.”

Makes for an interesting scenario in a country like China where there are 120 males for every 100 females.  If the science is accurate, more women will become pregnant with girls than boys.  And if the Chinese stay true to their traditions, the increase in number of abortions performed will be exponential.