On 01/06/2011 16:45, David Paste wrote:
On Jun 1, 1:21 pm, wrote:

Likewise we could extend human life by sterilising the off spring of those
that don't live a long time.

That wouldn't extend human life, it'd shift the mean, but then you've
got to take regression to mean into account - maybe the long-lived
ones were an anomaly?

Not necessarily - what you say would be right if human lifetime was
random, but it isn't - some people are more susceptible to eg heart
disease or cancer, so removing the people who die earlier would put a
selective bias towards the longer lived.

(at the moment there's little selective bias - most people live long
enough to breed, and that's what counts - the extra years afterwards
don't help much)