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Comment by richthegeek | Hacker News Reader

Standard Darwinian competition wouldn't matter here - people generally finish breeding (ages <35) long before they have trouble from cholesterol (ages 40+) or other minor dietary issues.

You could consider in the same way as the explanation for altruism - that families and communities who can rely on helpful old people to raise the children perform better and out-compete families/communities without that resource.

We should also consider that any dietary pressure will have only existed for at most a few thousands of years which, in evolutionary terms, 1000 generations perhaps, is basically nothing.

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That is not true. One of the many factors that make human tribes competitive is grandparents. Grandparents can help in many ways especially with child rearing and retain knowledge not available to younger people. Having more healthier and longer lived grandparents enhances the relative fitness of those of breeding age. There is a similar effect with homosexuals tending to contribute to tribal fitness thus enhancing reproductive fitness of the tribe.

Are there any data to support this?

Not yet. My ex is a geneticist who studies the evolutionary basis of aging and this is one of the hypotheses for human longevity being what it is, but there isn't hard proof so far.

>studies the evolutionary basis of aging

This sounds like it would be fascinating in general.

>> similar effect with homosexuals tending to contribute to tribal fitness thus enhancing reproductive fitness of the tribe.

If they want to reproduce, don't they have to search outside their tribe for a sperm/egg donor and possibly surrogate? So at least 50% or more of their reproductive health comes from outside the tribe?

I'm talking about behaviors and you are talking about desires. These are very different contexts.

Attempts to characterize behavior show homosexuals more commonly staying with parents and supporting relatives. The usual explanation for this is that they are not interested or able to compete in the usual mating and paring rituals. It isn't that they want to reproduce so much as they want to contribute to the tribe and in doing so result in the reproductive capacity of the entire tribe being increased.

> people generally finish breeding (ages <35) long before they have trouble from cholesterol (ages 40+) or other minor dietary issues

You’re speaking to modern times. Rebeccu, for instance, is a gorgeous town abandoned by Sardinians in the 14th century because of famine. Furthermore, the children of a famished mother are less likely to survive to reproductive age, and a family whose elderly died of famine will be less stable than one with multi-generational structures in place. These prenatal, neonatal and group selection dynamics bias the dice.

I'd suspect in the case of famine those who digest the cholesterol would have the highest survival rate. It still doesn't add up.

You don’t need famine; a wealthy societal elder is better positioned to marry his or her children and grandchildren into situations where they will have more children and their children will be better provided for. An elder male could continue reproducing by finding additional mates. There is good evidence that male genetic diversity is much lower than we would expect if most of our ancestors were monogamous.

Bugs might reproduce primarily constrained by their LDL uptake but humans are far more complex.

1000 generations is plenty of time for a new mutation to potentially achieve fixation in a relatively contained, small-ish (in human terms) population.

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