September 24, 2009
Agnar Helgason
Department of Anthropology
University of Iceland
101 Reykjavik
Iceland
agnar@decode.is
Dear Agnar Helgason:
It has been a while since I wrote. I thought I’d update you. I continue to be a great fan of yours on the basis or your article “An Association between the Kinship and Fertility of Human Couples.” The bottom line I take to be, “If you are not fairly close cousins, your fertility is going to be less than at a replacement level.” As I have mentioned, the same fact has been published in good scientific papers before and after yours, but yours remains the one with the cleanest numbers and the best translation into just how close those cousins need to be. Also, I had for years been asking everybody I could think of to do just the study that you did, even so far as going back 10 generations, so I have felt particularly gratified.
I do have a question on behalf of the readers on my web site. Your flagship graph:
(sorry I spelled your name wrong)
The graph is quite eloquent, but just how many children does the vertical axis represent? Dr. Labouraiu tried to explain it to me. He clearly understood, but I still cannot answer the question, “How many children can a pair of third cousins expect to have?” I think I told you my website is nobabies.net.
I have done my best to put the best information I have onto a DVD. I am enclosing a copy. It takes about 10 minutes to run. I would be happy to get your reaction.
I am posting this letter as an open letter on my website. I would be delighted to post anything you might have to add.
All the best,
Linton Herbert
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