August 25, 2023
to be posted on

João Zilhão
UB (Universitat de Barcelona)
Departament de Prehistòria
C/ Montalegre 6
08001 Barcelona
34 934037510

Dear Professor Zilhão:

First let me thank you for being champion for the Neanderthals.  (And forgive me for not writing “Neandertal.”  I resist adopting a new word that does not introduce a new concept.) 

I read about you with delight. (Michael Salter Neandertal Champion Defends the Reputation of Our Closest Cousins SCIENCE vol. 337 no. 6095 August 10, 2012 page 642)  I shall mention why I like Neanderthals and then go on to propose an idea for you.  I am innocent of serious knowledge about them, so this is just for fun.  I hope it will amuse you.  At one point I shall touch on something of which I have indeed made study and feel very sure of the ground, but whether it is relevant I really cannot say.  The bottom line will be this:  The position that Neanderthals were just as intelligent as Homo sapiens is not extreme; in fact there is reason to believe that Neanderthals were significantly more intelligent. 

First the personal note.  As a child I knew a number of men who looked like they might have been the models for artists who depicted Neanderthals in the past.  One of them was in the military when a barracks caught fire with many men still in their bunks overcome by the smoke.  A fire hose was in play but was obviously going to take a long time putting the fire out.  My friend had the others tie a rope around his waist and turn the fire hose on him.  Thus aided he went into the flaming building and grabbed two men, one under each arm, and was dragged back out.  Then he went back for more.

The story persuaded me that there is more to life than intelligence.  There is also nobility of spirit.  Thus without an actual logical connection, I have always looked up to Neanderthals.

They inform me that Homo sapiens first appeared in Africa from which they emerged and encountered Neanderthals in the Holy Land, where they were able to interbreed and most of the world now carries a proportion of Neanderthal genes.  I would suspect that there are more Neanderthal genes in the world now than there ever were before.  There is much of interest that has happened in the Holy Land, but it is not necessarily germane. 

When the first Homo sapiens entered Europe, where Neanderthals were well established, interesting things started to happen.  I think of flutes, chewing gum and the javelins.  These were unique for the time.  So why did it happen then and there?  The humans involved may had had bigger brains and been smarter than moderns, but in that realm they were no match for the Neanderthals.  So in the event of contact and the simultaneous cultural growth, it seems that it was the Neanderthals that supplied the brain power. 

But that still leaves the question as to why Neanderthals had not done this long before.  What magic did Homo sapiens bring to the encounter that the Neanderthal lacked?  Here I reach my own area of interest.

It is a well established but little known fact that kinship is related to fertility.  There is an optimal degree of kinship that Patrick Bateson calls “optimal outbreeding,” which turns out to be close to, but not quite, inbreeding. 

(The relevant articles are few but impressive: 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 AND An Association between Kinship and Fertility of Human Couples Agnar Helgason et al. SCIENCE vol. 329 no. 5864 February 8, 2008 page 813 – 816 AND Human Fertility Increases with marital radius. Rodrigo Labourian and Antonio Amorim.  GENETICS volume 178 January 2008 page 603 AND Comment on “An Association Between the Kinship and Fertility of Human Couples,” Rodrigo Labouriau and António Amorim SCIENCE vol. 322, page 1634b December 12, 2008.)
My idea is this.  During their long sojourn in Africa Homo sapiens learned to take this phenomenon into account, although I am sure they did not understand it.  We do not understand it still.  They learned to live and marry within small very isolated bands.  Given this custom, they could survive at any population size density.  Otherwise extinction beckoned.  This was not due to any great intelligence.  To paraphrase Aristotle, it happened by chance and it persisted because it worked. 

It is reasonable to ask why such an effect should exist.  Why did evolution produce such an inconvenient effect?  The answer is that in order for evolution to proceed, speciation is necessary.  When a new niche opens, the faster speciating form gets an early start exploiting the new opportunity.  This puts a limit on how big a random mating population can be.  This is spelled out on this link:  Also you will find other evidence.  For instance apparently speciation takes about two thousand generations, which implies a maximum random mating population below 1,000.  To keep populations below that size, they must be eliminated within about 10 generations.  I take a generation (prior to electric lights) to be about 30 years, so an urban civilization should not be able to survive more than three centuries.  As the link shows, that does appear to be the case. 

Of course one way to limit population size is to limit population density.  The Eskimo use this strategy.  Anybody an Eskimo meets is likely to be near enough kin for fertility to persist.  According to Robin Fox, the only other culture studied that takes the attitude “marry whom you will” is modern urban culture, which by and large has not yet passed the three century test. 

So our happy Neanderthal ancestors lived at low density and were innocent of prejudice or tribal obligation.  They were politically correct.  But suppose one of them invented, say, a fish trap.  Given a nice estuary, a forest and a stone axe it is easy enough to drive in stakes in a pattern that will trap fishing moving out to sea with the tide.  That means plenty of food.  Many are welcomed in.  Lots of traps are built.  But in a couple or three centuries the local population dies out and with it the idea.  Cave painting, on the other hand, ought not encourage an increase in population density and might survive. 

Enter Homo sapiens.  They are able to survive at high population density.  They learn the trick and flourish. 

I do notice that the non-Neanderthal population of Africa persists in having extremely strong family ties, but it’s only an idea.  Feel free to shrug it off.  The kinship-fertility effect is true enough, but the idea that this was the critical contribution of Homo sapiens would be hard to establish, particularly in our politically correct culture, which rejects any such idea out of hand. 

But I thought you might enjoy it.  You might also enjoy tormenting those who say mean things about my friends the Neanderthals. 


M. Linton Herbert MD

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