April 23, 2013
to be posted on nobabies.net
John L. Hoogland
University of Maryland Center for Environmental Science
Appalachian Laboratory
Frostburg, MD 31532
hoogland@al.umces.edu
Dear John Hoogland:
I have read your splendid paper (John L. Hoogland Prairie Dogs Disperse When All Close Kin Have Disappeared SCIENCE vol. 339 no. 6124 March 8, 2013 page 1205) and before getting down to business would like to gush that this is what seems to me to be science at its best: patient work observing until a pattern emerges and interpreting the pattern. You studied prairie dogs for 31 years. That’s wonderful. I have been looking at my fruit flies for four or five years and I thought that was a long time; too long for a high school science project or generally even a graduate student. And you did it on your own. I like that. I also like the fact that they are still called prairie dogs. Somebody decided that starfish shouldn’t be called such because they, “Aren’t really fish.” They aren’t stars either, are they? But we have been threatened with “sea star” as a replacement. Down to business.
My own interest is in mating strategy as it applies to reproductive success. Patrick Bateson has shown that with Japanese quails there is a preferred strategy whereby a female is less drawn to brood mates than to cousins but more drawn to cousins than to unrelated males. Patrick Bateson Mate Choice (Cambridge University Press Cambridge 1983) So there is a preferred degree of kinship. This is reflected in a maximum fertility at least in humans at about third cousin. (That’s oversimplifying.) (An Association between Kinship and Fertility of Human Couples Agnar Helgason et al. SCIENCE vol. 329 no. 5864 February 8, 2008 page 813 – 816) there is more at http://nobabies.net/A%20December%20summary.html
What is lacking is good data showing the time course of fertility with regards to kinship over multiple generations. The Helgason article looks at children and grandchildren but not beyond. There is a suggestive study (Low fertility increases descendant socioeconomic position but reduces long-term fitness in a modern post-industrial society Proc. R. Soc. B 2012 279, 4342-4351 first published online 29 August 2012 Anna Goodman, Ilona Koupil and David W. Lawson) that appears to show even more pronounced loss of fertility of unrelated (Yes, that’s a misnomer; I mean very distantly related) people but it requires accepting prospertity as an indicator of reduced kinship of a couple.
A colleague and I have published an article about fruit flies in which I follow fertility against population size as a proxy for kinship. (We took pains to discourage the population from subdividing itself.) I shall attach the paper. But looking at all the data it appears that the time course for mice and humans is quite different from that for fruit flies. On the face of it the flies are responding to a mechanism mediated by post-zygotic infertility – infertility occurring after the egg is fertilized. On the other hand mice and humans seem to add a pre-zygotic mechanism, something that prevents fertilization.
But when I add it all up the result is not totally satisfactory and almost all the evidence is indirect. Fanfare of trumpets. Enter you with thirty one years of experience observing prairie dogs. That is many generations. If you can estimate kinship of mating pairs and their reproductive success over subsequent generations you may find a relationship like the one in the studies I cited above and carry that estimate over several generations. The data I have suggests that the process works itself out over about ten generations; the mechanism reaches back about that far in detecting consanguinity. This is the same span as the Helgason article examines.
Of course there can hardly be a more important topic than who has babies and how many. This effect appears to be true in mammals, birds, fish, insects. (On the Regulation of Populations of Mammals, Birds, Fish and Insects, Richard M. Sibly, Daniel Barker, Michael C. Denham, Jim Hope and Mark Pagel SCIENCE vol. 309 July 22, 2005 page 609) So whatever works in prairie dogs probably works in humans.
Is there any chance that you have data in a form you could search and work out just what is going on? I think you might find it exciting.
Sincerely,
M. Linton Herbert MD
I received a prompt and warm hearted reply from the professor and look forward to seeing what he publishes next. LH
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