Mates per human?

October 3, 2006 2:56 PM

I'm trying to track down a graph I once saw in a book - pretty sure it was an evolutionary psychology book - that compared the ratio of number of mates/sexual partners with either brain or body size among primates. Humans fell somewhere in the middle, at about 2.5 mates each (i.e. an argument about how "natural" monogamy is to our species.) Any ideas?
posted by gottabefunky to Science & Nature (10 answers total)

There is some information along those lines in The Third Chimpanzee.
posted by Riemann at 3:05 PM on October 3, 2006

Are you thinking of testicle size perhaps?
posted by fvw at 3:23 PM on October 3, 2006

Greater Male to female size ratios correlates with greater polygamy (number of female partners males have). Testes size correlates with male polygamy and sex competition among males for females, and with multiple makes mating with the same female (sperm competition).
posted by orthogonality at 3:25 PM on October 3, 2006

"Multiple males", that is.
posted by orthogonality at 3:25 PM on October 3, 2006

I doubt anyone is going to be able to track down a specific graph for you and since you didn't provide any information about the book, I'm assuming you're not actually looking for the graph, but just information on this subject.

This is a well-researched idea in the field of anthropology for sure. There are tons of papers written on body size and penis/testicle size in relation to mating patterns. There's tons of stuff on the internet about this, so using a few choice keywords in google will turn up a wealth of info. As an example, I typed "testicle size monogamy" and found plenty of pertinent results.
posted by Paul KC at 6:33 PM on October 3, 2006

Response by poster: Hmm, I don't remember it as being testicle size, but I do remember it as represented in a single graph. Maybe brain:body size ratio.

I thought it was in Grooming Gossing and the Evolution of Language, but can't find it there. Red Queen? The Naked Ape?

What I remember was that it implied that human males were "evolved" to mate with ~2.5 females, based on this size ratio. I'm curious what the X-axis measurement was.
posted by gottabefunky at 7:15 PM on October 3, 2006

I'm pretty sure it's from The Third Chimpanzee. There's a bunch of talk about monogamy and mate ratios, anyways.
posted by Mr. Gunn at 7:54 PM on October 3, 2006

I took a course on human evolution (from this professor) that dealt with this topic. The syllabus and the list of textbooks (both decidedly Web 1.0). I'm guessing we covered it in the fifth class, "Primate Behavior."

So you may want to get your hands on a copy of Jolly, CJ and White, R., Physical Anthropology and Archeology, fifth edition, and check out pages 167-178.

I no longer have the course reader that gave the title of so-and-so's "fifth article," so these are guesses:
-Rosenberg & Trevathan -- "Birth, Obstetrics, and Human Evolution," apparently on Blackwell (I can't see it).
-Small -- no idea who or what, and I'm not sure how to Google for it.
-Smuts -- Barbara, I presume -- has written plenty in this general area, and I'm not sure which article the syllabus means.

I'm almost positive Jolly & White will cover it adequately anyway.
posted by booksandlibretti at 8:05 PM on October 3, 2006

Sexual Dimorphism in Hominids (chart)

Sexual dimorphism and mean harem size in pinnipeds, ungulates, and primates (graph)

Hot artsy chick with violet eyes who fits search terms (photo)
posted by orthogonality at 9:07 PM on October 3, 2006

I am pretty sure that Dawkins has that chart in The Ancestor's Tale.
posted by Uncle Jimmy at 6:34 AM on October 4, 2006