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Comment by causi | Hacker News Reader

why the fossil record is mostly males

Because it can be, that's why. Population bottleneck is female reproduction. You can impregnate X females with X males, or 0.5X males, or 0.25X males. Wiping out males has a much lower effect on the future population of a group than wiping out females, so over time a group that loses a lot of males is better off than a group that loses a lot of females, and has more members to die and become fossils.

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Such statistical arguments ignore one important fact: every dinosaur died. All of them. So the difference is not so much whether they died or how important it was. The only pertinent issue is how they died and why that might change the statistics on fossilization.

Every *non-avian dinosaur died.

Most birds alive today will not be in 20 years.

This can explain why males die younger. It doesn't mean that more males than females die.

An animal that makes it to old age to get picked off by whatever predators follow the herd or keel over from disease is going to become food for something else, not a fossil.

When has the population of females ever been 4x the population of males?

Perhaps it has more to do with risk profile and group dynamics?

Not even close to 4x but in post-WWII Russia there were 1.21 females for every male.

After war time, this wouldn't be surprising. All the males in a tribe can easily get wiped out in one or two engagements, leaving only females and children.

In Russia after WW2 the ratio of female:male was 4:3

Imagine what that ratio would have been after a war in olden times.

I'm not saying it has. I'm saying that a small number of males can impregnate a large number of females.

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