September 20, 2011
To be posted on

Peter Forster
Murray Edwards College
University of Cambridge
Cambridge CB3 ODF

Dear Peter Forster:
I enjoyed the article you wrote with Lord Renfrew (Peter Forster and Collin Renfrew Mother Tongue and Y Chromosomes SCIENCE vol. 333 no. 6048 September 9, 2011 page 1390)  It is a pleasant irony to think that the “mother tongue” seems to be carried with the father’s lineage so often. 

It is always a pleasure to look at careful work and I find it particularly nice when someone takes an interest in any process that spans multiple generations of people.  Most of us spend most of our time working with far shorter attention spans, maybe a few seconds.

I was hoping you might comment on Britain.  I have long taken an interest in the ancient British people and as a result have been obliged to change my opinion any number of times as data rolled in over the decades.  I have high regard of the opinion of experts, but I have higher regard for their evidence.  In my own field of diagnostic radiology, evidence trumps instinct just about every time. 

Recently I read Saxons, Vikings and Celts by Bryan Sykes and thought, “All right.  I’ll believe that.  At least it’s all in one place and I can find it.”  The definition of Celt seems to have undergone a sea change.  I used to think, “Ah yes, a population that arose in the bronze age characterized by an Indo-European language, Indo-European pantheon, exquisite crafts, representational arts, tribalism and love of horses.”  Of course none of those things arose in Britain, and there were people living in Britain long before any of them arose, so I made what I think to be the understandable assumption that the most ancient people of Britain were not in fact Celts. 

Sikes has shown me the error of my ways, so I now must believe that the Mesolithic Britons were Celts AND the master builders who came (sorry, “went,” I’m over on this side of the Atlantic, aren’t I?) to Britain in Neolithic times were Celts.  Together of course they are most of British genes. 

Well just because I believe it doesn’t mean I have to say it, so if you will forgive me I shall go with my old usage. 

The thing is that prior to the coming of the Angles and Saxons, the languages of Britain were Celtic.  Hardly a word survives from the time before the Celts.  I have it from a good source that “Carlyle” may be pre-Celtic, but that’s all I have heard of.  And of course Celtic languages, Celtic tales, Celtic tribalism and I suppose music remain.

The devil of it is that there are no Celtic genes.  No Y chromosomes.  No mitochondria.  They had to have come over in substantial numbers in order to dominate the whole archipelago.  You might be able to learn a language in the absence of people for whom it is a first language, but you will hardly make your first language one that is not spoken locally. 

Your article is concerned with whether languages follow the male line or the female line.  This is a case of equal opportunity extinction, so strictly speaking is not your interest.  But the question remains, what hit them? 

I have an idea that requires one assumption, from which all else follows.  The assumption is that they were pretty decent folk.   As being unquestionably the high status segment of the population they had every opportunity to exploit the natives sexually.  They could have been tumbling the local girls had they so chosen; who could have stopped them?  Had they done so, Y chromosomes would have lingered after the bulk of the Celts vanished.  And had they occasionally kicked a young person out to make his way among the under privileged, mitochondria would have persisted.  So when the bulk of them died, all died and there was no trace except for their culture.

So we have the rich, the dominant, the privileged dying while others lived.  That, as it turns out, is exactly what you would expect. 

Here is a graph that shows the results of a study made using the Icelandic genealogy. 

Graph is from An Association between Kinship and Fertility in Human Couples, Agnar Helgason, Snaebjoern Palsson, Daniel Abjardson, Pordur Kristjansson and Karl Stefanson, SCIENCE vol. 319 February 8, 2008 page 813.

They compared the kinship of couples with the number of children they had.  When they looked at grandchildren the curve was about the same except that there was a reduced number of grandchildren among those more closely related than second cousin (according to their reckoning, which is not the standard one).  By the time you reach seventh cousins you are below replacement. 

The moral is clear.  The big gene pool shrinks in the long run.  (And there is evidence that the run is not very long, but with your scope that is not relevant.)  The Celts kept their tribal, no doubt clan, structure, but their social horizon was still pretty big.  There might be thousands in an identified tribe.  That is simply too many.  Contrast that with the social horizon of the under privileged; they were pretty much marrying within the hamlet, or at most with an adjacent hamlet.  Their fertility was fine. 

It seems to me, begging your pardon, that this effect is not sufficiently recognized when people look at the fates of populations.  Yet it is the single most significant factor.  No babies, no population. 

I thought you might be interested.  Let me know what you think.  There is much more of this kind of thing on my web site, but if you like I can make it rather more succinct.

Thank you.


M. Linton Herbert MD

Dr. Forster was kind enough to send a reply, making him one of the tiny number who have extended that courtesy.  He made some interesting points, but since he did not give me permission to place them here, I shall let him place his ideas where he will.  I do think it is reasonable to mention that he and, I believe, Professor Colin Renfrew have a book coming out in 2012, which should address some of the things I mentioned in this letter I sent to him. 

He did not, however, address the issue of large populations and falling fertility.  I believe this means either 1) I have not made my point clearly 2) I have not put together enough evidence or 3) I’m wrong. 

Oh well.  This is far better than those who will not answer.  So I thank him profusely and look forward to his coming book. 

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