August 10, 2010

Daniel Sarewitz
Co-director of Consortium for Science, Policy and Outcomes
Arizona State University

Dear Daniel Sarewitz:
You are so right.  (Not by Experts Alone NATURE vol. 466 no. 7307 August 5, 2010 page 688) You point out that once an important technology is in use, restricting,, reorienting or replacing it becomes incredibly difficult.  If I might be so bold as to extend the principle, once an important idea is accepted by the experts, changing it becomes incredibly difficult. 

My own interest is inbreeding – not incest – inbreeding, marrying second or third cousins out to say fifth or sixth cousins.  Expert opinion goes back many years to a man who walked around Appalachia talking to people about their families.  By collecting enough genealogies and learning about the incidence of things like hair lip, mental deficiency and color blindness (Don’t hold me to exactly which things.  It’s been a long time.) he was able to demonstrate that genes were inherited in humans according to the standard Medelian laws of genetics.  This was no big surprise.

When the experts looked at his data, they noticed that feeblemindedness (the term that would have been used at the time) could behave as a Medelian recessive, and thus the particular cases involved probably would never have happened had there been no consanguinity.  Good so far.  Thus inbreeding causes feeblemindedness.  Foul!  There was no control group.  Nothing could be concluded except that apparently genes are real in humans. 

In fact in that location at that time, the overwhelming majority of people in institutions because of mental deficiency were there because of Rh incompatibility.  If an Rh positive baby is born of an Rh negative mother, and he is not the first Rh positive baby, and the standard of care is what it was then, he will probably be brain damaged as will all subsequent Rh positive siblings.  The moral is, if you are going to be born Rh positive, don’t have an Rh negative mother, and if you are an Rh positive man, don’t marry an Rh negative woman.  Since at the time, the Rh factor had not been worked out, the only thing that would reduce the number of Rh positive babies that got into trouble was consanguinity.  The effect is not very strong, but the bottom line is that inbreeding reduces feeblemindedness.  Modern care has changed things a great deal, but even now there is very good logic – although I know of no one who has tried to gather data – that if you are going to be an Rh positive baby you still don’t want and Rh negative mother. 

When this came out, did it cause people to say, “Oh, how wrong we were.  That was the wrong conclusion.  It isn’t so bad after all”?  Not a bit of it.  In fact the prejudice crops up on page 698 of the same issue of NATURE as your own article.  The title is “Close Relatives are Bad News.”  They are having a little fun with an ambiguity in the phrase “close relative.”  As was pointed out in “A Series of Unfortunate Events,” it can mean physically close, emotionally close or genealogically close.  In this case they mean physically close, and they do not mean relatives, they mean members of the same species.

What they are discussing is that a seedling in the jungle of Panama is less likely to survive if it happens to be near a member of the same species.  This results in the species being rare, or at least widely separated.  Since seeds and pollen only travel a finite distance, the effect is to reduce gene pool size.  It promotes inbreeding.  Yet the title slams inbreeding.

There are a number of reasons people might want children, but high on the list has to be the hope that there will be grandchildren.  Let’s just say for argument’s sake that grandchildren are good. 

If so, then inbreeding is good.  It’s not just OK.  It’s good.  In fact it is absolutely necessary in the long run.  If nobody marries cousins, then we will go extinct.  There is an enormous amount of data to support that.  I have squirreled a lot of it away on  For convenience, here are three key references. 

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 no. 309 July 22, 2005 page 607.

An Association Between Kinship and Fertility in Human Couples, Agnar Helgason, Snaebjörn Pálsson, Daniel Guöbjartson, Pórdöur Kristjánsson and Kári Stefánson, SCIENCE vol. 319 no. 319 February 8, 2008 page 813.

Comment on “An Association between Kinship and Fertility of Human Couples”, Rodrigo Labouriau and António Amorim SCIENCE vol. 322 no. 5908 December 12, 2008 page 1634.

They all present data that follows the same form.  Each independently proves what I say.  Marry cousins or die out. 

I have made it my business for the past ten or so years to run the truth down and to point it out to the experts.  Finding the truth has been pretty easy.  Getting experts to pay the slightest attention, even the experts whose data I cite, has been essentially impossible; those experts are needed to agree on just what advice to offer people. 

And now you point out that a technology (and you could describe mating strategy as a technology) has been adopted, it is incredibly difficult – by which I mean effectively impossible – to change it.  I don’t have a prayer.  I never had a prayer. 

That’s not good news, but it is the kind of thing one ought to know.


M. Linton Herbert MD 

I’ll put this letter on unless you can think of a reason not to.  I put everything there that I think is relevant. 

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