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gwern comments on Differential reproduction for men and women. - Less Wrong

5 Post author: NancyLebovitz 02 April 2013 11:48AM

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Comment author: gwern 02 April 2013 02:40:10PM *  45 points [-]

7 comments and no answers...? Regardless, you could have answered this question pretty easily and I don't think this was Discussion-post-worthy (certainly a reasonable Open Thread question). But I'll answer your question anyway.


The second line of the linked talk says:

For more information on this topic, read Dr. Baumeister's book Is There Anything Good About Men? available in bookstores everywhere, including here.

A search of 'Is There Anything Good About Men' in the usual place turns up a copy. Download. What are we looking for? A reminder, the key lines in the linked speech are:

...It’s not a trick question, and it’s not 50%. True, about half the people who ever lived were women, but that’s not the question. We’re asking about all the people who ever lived who have a descendant living today. Or, put another way, yes,every baby has both a mother and a father, but some of those parents had multiple children. Recent research using DNA analysis answered this question about two years ago. Today’s human population is descended from twice as many women as men. I think this difference is the single most under-appreciated fact about gender. To get that kind of difference, you had to have something like, throughout the entire history of the human race, maybe 80% of women but only 40% of men reproduced.

We could search for various words or phrase from this passages which seem to be relatively unique; as it happens, I chose the rhetorical "50%" (but "80%", "40%", "underappreciated", etc all would've worked with varying levels of efficiency since the speech is heavily based on the book), and thus jumped straight to chapter 4, "The Most Underappreciated Fact About Men". A glance tells us that Baumeister is discussing exactly this topic of reproductive differentials, so we read on and a few pages later, on page 63, we hit the jackpot:

The correct answer has recently begun to emerge from DNA studies, notably those by Jason Wilder and his colleagues. They concluded that among the ancestors of today’s human population, women outnumbered men about two to one. Two to one! In percentage terms, then, humanity’s ancestors were about 67% female and 33% male.

A C-f for "Wilder" takes us to pg286, where we immediately read:

...The DNA studies on how today's human population is descended from twice as many women as men have been the most requested sources from my earlier talks on this. The work is by Jason Wilder and his colleagues. I list here some sources in the mass media, which may be more accessible to laypersons than the highly technical journal articles, but for the specialists I list those also.

For a highly readable introduction, you can Google the article "Ancient Man Spread the Love Around," which was published September, 20, 2004 and is still available (last I checked) online. There were plenty of other stories in the media at about this time, when the research findings first came out. In "Medical News Today," (www.medicalnewstoday. com), on the same date in 2004, a story under "Genes expose secrets of sex on the side" covered much the same material.

If you want the original sources, read Wilder, J. A., Mobasher, Z., & Hammer, M. F. (2004). "Genetic evidence for unequal effective population sizes of human females and males". Molecular Biology and Evolution, 21, 2047-2057. If that went down well, you might try Wilder, J. A., Kingan, S. B., Mobasher, Z., Pilkington, M. M., & Hammer, M. F. (2004). "Global patterns of human mitochondrial DNA and Y-chromosome structure are not influenced by higher migration rates of females versus males". Nature Genetics, 36, 1122-1125. That one was over my head, I admit. A more readable source on these is Shriver, M. D. (2005), "Female migration rate might not be greater than male rate". European Journal of Human Genetics, 13, 131-132. Shriver raises another intriguing hypothesis that could have contributed to the greater preponderance of females in our ancestors: Because couples mate such that the man is older, the generational intervals are smaller for females (i.e., baby's age is closer to mother's than to father's). As for the 90% to 20% differential in other species, that I believe is standard information in biology, which I first heard in one of the lectures on testosterone by the late James Dabbs, whose book Heroes, Rogues, and Lovers remains an authoritative source on the topic.

(I jailbroke Shriver 2005 for you. Wilder et al 2004, incidentally, fits well with Baumeister remarking in 2007 that the research was done 2 or so years ago.)

And of course you could've done the exact same thing using Google Books: search "baumeister anything good about men" to get to the book, then search-within-the-book for "50%", jump to page 53, read to page 63, do a second search-within-the-book for "Wilder" and the second hit of page 287 even gives you the exact snippet you need:

Sources and References 287

...If you want the original sources, read Wilder, J. A., Mobasher, Z., & Hammer, M. F. (2004). "Genetic evidence for unequal effective population sizes of human females and males". Molecular Biology and Evolution...

Comment author: NancyLebovitz 02 April 2013 04:47:48PM 4 points [-]

Thanks for the information.

It would be harder to find out the relative effects of various filters: no children, children don't reproduce, grandchildren don't reproduce, etc.

One of the few instances of pervasive modesty among people is underestimating how good they are at things, and getting irritated at all the other people who don't seem to pass a minimal standard.

As it happens, your comment joins two other recent instances of my failing to notice valuable information at the bottom of a post, so that's a habit I need to change.

Since I didn't realize Baumeister had written a book, I did a few word searches (including in google scholar) and didn't turn anything up. I'd previously raised this as a discussion question, and didn't get any answers suggesting a solid source.

Comment author: ChristianKl 04 April 2013 05:05:31PM 0 points [-]

It would be harder to find out the relative effects of various filters: no children, children don't reproduce, grandchildren don't reproduce, etc.

Shouldn't the amount of children that don't reproduce be the same for men and women?

Comment author: NancyLebovitz 05 April 2013 01:48:00AM *  2 points [-]

That sounds reasonable, but I'm not sure whether there are countervailing factors when we're talking about lineages. When I say I'm not sure, I mean that I'm just not visualizing the logic clearly enough to have an opinion.

Also, if we're tracking male chromosomes to find out whether men have had children, do we lose track of their daughters?

How much does it matter in ordinary life that descendants presumably follow a power law distribution (lots at the top) rather than a bell curve?

How much of cuckoldry is break-even? That is, a man might be raising another man's child, but some other man might be raising his child.

Does people becoming less violent make a difference to the chances of male reproduction?

Onwards to hypothetical land: How much do men care about having descendants that they will never see? There are occasional scandals in which men who own sperm banks substitute their own sperm, which is interesting because no sex is involved. It also leads me to wonder whether male staff at sperm banks can be trusted.

Comment author: ChristianKl 05 April 2013 02:54:04PM 2 points [-]

Onwards to hypothetical land: How much do men care about having descendants that they will never see?

That depends a lot of the particular men. There are man who do care about it but I think the majority doesn't. Sperm banks pay donors instead of the donor paying for the sperm bank accepting it's sperm.

Comment author: gwern 02 April 2013 04:52:25PM 0 points [-]

It would be harder to find out the relative effects of various filters: no children, children don't reproduce, grandchildren don't reproduce, etc.

Yes, you'd need much more detailed genealogical information. There's tons of modern genealogies, of course, but how useful are those outside the modern era?

Since I didn't realize Baumeister had written a book, I did a few word searches (including in google scholar) and didn't turn anything up.

His book was the second sentence in the page. :)