>From the gene's point of view, the biological struggle between the
>generations is very real, and once Mom and Pop have done a good
>job of getting the tyrannical little genes into young Boomer, then
>as far as the gene is concerned, goodbye Mom and Pop! Especially
>if they're competing with young Boomer for foraging territory.
That might explain why kids kill their parents (they do?), but doesn't seem
to address JP's question. After all, it takes Boomer somewhere between 12
and 30 years to pop out Boomer Jr, but Mum and Dad are still in there
replicating like fiends, once a year and sometimes twins. If they stayed
fertile, Myrtle, they'd always be ahead of the game.
The real answers are going to involve complex interactions and costs.
Beating the critters that feast inside humans is surely one key to this -
sex as immunological remixing to stay Red Queened. And childhood enhancers
that just happen to involve deferred costs and luckless synergisms. I've
always assumed that since the germ line is passed straight down from the
year dot, with mutations but no senescence, the DNA-cleanup equipment used
to keep its shoes shined must be way too expensive to mass-produce for the
grunts, even the smart guys in the CNS.
Randolph Nesse and George Williams discuss this stuff in their recent book
on darwinian medicine (EVOLUTION AND HEALING in the UK, something else in
the USA), but wimp out at the crucial points - presumably because it's too
soon to say anything really informed.
Damien Broderick