Tim Kohler
Department of Anthropology
PO Box 644910
Washington State University
Pullman WA 99164-4910

Dear Professor Kohler:
I read Virtual Archaeologists Recreate Part of Ancient Worlds, Michael Bawaya SCIENCE vol. 327 no. 5962 January 6, 2010 page 140 expecting mostly entertainment, but when I got to your work klaxons went off in my head.  The article says that the Ancestral Puebloans vanished from the Four Corners area after about 340 years of success.  There is an element that was not mentioned that might be relevant.

There was another group of Anasazi, those living in Long House Valley.  They lived for a time at low density.  Then their numbers rose dramatically but the valley fell empty after about 300 more years.  A study was described in a paper by Jarred Diamond, Life with the Artificial Anasazi.  I am sure you are familiar with it.  In the paper it is noted that tree ring thickness and population size correlate closely over a long time and over large swings.  The conclusion reached is that the population that could be supported depended on rainfall.  That conclusion leaves a couple of serious questions.  For one: for generations after the first settlement the “rainfall” was far less than what could support the population.  Likewise at the end the farmers all “moved away” even though the “rainfall” was still better than it had been for most of the sojourn.  For another: looking at the population – actually a count of occupied dwellings – one can easily see years of immigration.  Multiple families moved in together and the count increased stepwise.  Yet there are essentially no stepwise declines in occupied houses.  Hence it seems apparent that nobody ever left.  They just died out.  The correlation must then be caused in the other directions.  They were taking wood and doubtless pruning and cultivating the trees.  This would be unsurprising.  Nobody else, lease of all Europeans, ever managed to farm there.  These were experts.

So why did they die?  War, famine and plague should have resulted in stepwise declines just as emigration would have.  As it turns out, civilizations regularly fail within about 300 years and the likelihood of their doing so increases with age.  As the enclosed DVD will show, their chance of continued survival either declines steadily or stays high until about 300 years and then crashes.  The only reasonable explanation I can come up with is that there is a genetic limit to the size of a population.  When the limit is exceeded, then the clock starts running.  I have written a computer program that models how the genetics could work, also explained on the DVD. 

When it was mentioned that you believed that at one point multiple small social units merged into a single large unit I thought “Aha if nothing else, that would have finished them in time.” 

I would encourage you to look at the evidence I have sent.  It only takes 10 minutes.  If you have any questions or I can help in any way, do let me know.  If you want to read more, I post such evidence as I can find on NoBabies.net along with correspondence. 


M. Linton Herbert MD
Nobabies.net and SilentNursery.com 

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