March 23, 2010

Patricia McAnany
Room 211, Alumni Building
Department of Anthropology, CB# 3115
University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-3115

Dear Patricia McAnany:
I am delighted to observe that the inherently distasteful subject of the collapse of civilizations it getting its day in the sun.  I have been poking about the edges of the subject for several years.

What I have discovered is this.  In humans as in other animals fertility is determined by the size of the mating pool.  Pretty much the smaller the mating pool the greater the number of offspring, bar truly intense inbreeding.  This may not seem to be intuitively likely, but there is massive evidence to support it and no contradictory evidence I have found in all my searches.

Evidence is presented on the enclosed DVD and more on the enclosed poster.  More, along with my letters to experts, is to be found at 

Armed with this fact – sorry if you don’t believe it, but the amount of evidence is overwhelming – it is interesting to go back over the Mayan experience you recount in your chapter in Questioning Collapse.  One observation you make is that in the hinterlands the primary Mayan producers flourished for over a thousand years, while in the big cultural centers where the heroic monuments were built there was no such long term survival.  It is difficult to look at the numbers and make much sense because the actual phases of Classical Mayan civilization were rather few.  But if you lump them together with the Romans (who lasted a long time in name but had periodic times of upheaval and shift in the center of political power) and the phases of Chaco Canyon civilization, you get this.  I graph ages of the regimes at the time of collapse on the horizontal axis and the probability in fifty year increments that the civilizations reaching that age will persist another half century.

Information taken from BBC and The Collapse of Complex Societies.  Joseph A. Tainter.  Cambridge University Press.  Cambridge.  Eighteenth printing, 2009. 

You see the pattern.  Civilizations age and die.  The rural people go on.  It is just a matter of fertility.  Urban people have a larger social horizon, in fact too large.  After a fixed number of generations they die out.  Primary producers must be content with marrying cousins so they survive indefinitely. 

This is not a phenomenon unique to this part of the world as the enclosed material will make clear, although local differences do profoundly influence the shape of the curve.  It is rather eerie that intelligent people undertake to discuss collapse without ever addressing the question, “Just when do these places have their crises, anyway?”  The rudimentary analysis I have done already rules out every single explanation proposed by Jarred Diamond or proposed by those who question him.  Read my lips: the opossum is up this tree, not one of those. 

You mention that civilizations undergo a cycle.  Who would have thought the cycle was so strictly maintained?  I doubt my old metronome keeps time that well.  Cycle it does.

As for the question, “Do leaders in civilizations make terrible mistakes?” the answer is obviously, “No.  They only make one terrible mistake, and it’s always the same mistake.” 

Any competent bureaucracy has to keep tabs on the people it influences.  The contrast between rural fecundity and urban sterility is obvious to the most casual observer.  But by and large the power elite steadfastly ignore it. 

So suppose you walked up to a classical Mayan leader and said in clear Mayan, “If you want to keep your civilization alive you must have the critical members of your population limit their socialization to tight little groups, just like they do out in the countryside.”  I can tell you with great confidence what the response would be:


You would not get a response.  Here is an issue that dwarfs any other concern they could possible have.  And they would ignore you.  Even if they boasted of their willingness to look at evidence and you had mountains of evidence, they would ignore you. 

I know because I have tried it again and again. 

So keep up the good work.  If enough people take an interest in collapse the truth must some day come out.  I shall go on doing my own best.  Some help would really be a nice thing.  Meanwhile if you want any further clarification or I can help in any way, do let me know.


M. Linton Herbert MD and 

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