[quotemstr]

You've identified the mechanism by which sexual selection operates. It's clearly a powerful force.

This paper is arguing that in addition to sexual selection's first order directional effect, there's an overlaid second order effect on variability, and the argument makes sense. Male reproductive success is already highly variable, because male gametes are cheap. Some males end up being disproportionately successful, e.g., Genghis Khan. From a gene's point of view, being hosted in Khan was winning the jackpot.

If you have a number of male offspring, some of them will be evolutionary "duds" no matter what. If you increase the variability in reproductive success of your male children, then some of them will be less reproductively successful and others will be more successful. But there's an asymmetry: "duds" are already duds and can't be made less successful, but on the other side of the curve, by increasing variability, you increase the likelihood of a jackpot.

The effect doesn't apply to female children, since a female mammal cannot have 200 offspring in her lifetime, but a male mammal certainly can.

(Your fruit analogy is inapt, since fruit in a bag don't reproduce among themselves and regress toward the population mean.)

[mirimir]

> ... since a female mammal cannot have 200 offspring in her lifetime ...

Ah, but now she could. With enough money to pay for enough surrogates (or eventually, machines) and childcare.

So maybe, going forward, there'll be more variability in human female reproductive success. Interesting.

[quotemstr]

Yeah. Various kinds of reproductive and genomic technologies invalidate general evolutionary assumptions, but the techniques haven't been around long enough or been common enough to matter so far. But in the future? Who knows?

[haihaibye]

And if there was any kind of genetic motivation for doing that (and almost everything is partly heritable) we'd see more of those genes next generation, so likely some of her kids would go down that route too and there we go...

[brenschluss]

>The effect doesn't apply to female children, since a female mammal cannot have 200 offspring in her lifetime, but a male mammal certainly can.

From the paper:

"Note that this theory makes no assumptions about differences in means between the sexes, nor does it presume that one sex is selective and the other non-selective"

So the reproduction capacity of sex A and sex B is equal. I'm attempting to debate the paper strictly based on its own arguments.

[quotemstr]

The paper then goes on to discuss, in detail, how differences in selectivity drive differences in variability, so the passage you quoted does not mean that the author is imagining A and B to be equally selective. The author is just asserting that both of his arbitrary sexes might be selective in an absolute sense.

I'm not sure what point you're trying to make, especially since you've opted not to quote or address the majority of my comment.

[brenschluss]

> This paper is arguing that in addition to sexual selection's first order directional effect, there's an overlaid second order effect on variability, and the argument makes sense. Male reproductive success is already highly variable, because male gametes are cheap. Some males end up being disproportionately successful, e.g., Genghis Khan. From a gene's point of view, being hosted in Khan was winning the jackpot.

The paper makes no distinction between sexes -- so a discussion of male or female differences, whether in reproductive success, does not discuss on the paper's model.

> If you have a number of male offspring, some of them will be evolutionary "duds" no matter what. If you increase the variability in reproductive success of your male children, then some of them will be less reproductively successful and others will be more successful. But there's an asymmetry: "duds" are already duds and can't be made less successful, but on the other side of the curve, by increasing variability, you increase the likelihood of a jackpot.

Your argument holds the selectivity of the female sex as constant, and discusses variability of the male sex.

The paper's argument is about variability in one sex ('sex B') being a function of the selectivity of sex A. These are fundamentally two different arguments, and so whether your argument is true or not, your argument does not discuss the paper's model.

> The effect doesn't apply to female children, since a female mammal cannot have 200 offspring in her lifetime, but a male mammal certainly can.

Addressed in a previous comment.

> (Your fruit analogy is inapt, since fruit in a bag don't reproduce among themselves and regress toward the population mean.)

Thank you - I did not know this until now. I assumed that fruit reproduced asexually in bags.

My fruit analogy is presented because the error that the paper seems to make happens at a simple statistical level -- because the paper assumes that you can 'sort' a two variably desirable populations (B1 and B2) on a histogram by desire, find the top 25% of the population (B11), and assume that the top 25% desirable population (B11) is as variable as the original population it came from (B1).