December 3, 2009



Goram Penev
Department of Planning and Regional Development
University of Thessaly
Pedion Areos
GR-38334 Volos – Greece


Dear Goram Penev:
I read in ECONOMIST how there is concern for the fertility rate of Serbia.  What truly caught my eye was that hundreds of thousands of Serbs had come in from Bosnia, but the birth rate did not rise as hoped.  Actually that could have been predicted.  The influx, in the absence of understanding what determines fertility, was the last thing you needed. 

Fertility depends on kinship.  If you want people to have babies, have them marry third or fourth cousins.  It is a little more complicated, but that is the essence.  The ECONOMIST article attributes low fertility to economic factors, and they may indeed play a part.  It is notorious how fertility usually ignores economics.  Poor people don’t stop having babies.  People who marry those they are only distantly related to stop having babies. 

Ample evidence and appropriate references are included on the enclosed DVD. 

There are subtleties to the science that need to be worked out, but the problem itself is not subtle.  If sufficiently close kin do not marry, fertility will fall to zero.  At least that is my understanding.

Think about it.  If the fertility rate fell to one for a number or generations, one would have solitary children in the first generation, solitary first cousins in the second, solitary second cousins in the next and so forth.  Eventually there are no cousins close enough to have two children.  But in fact as you well know problems develop a lot faster than that.  If I were to bet, I would say that the year fertility fell below replacement was the year when it was no longer possible for a population to survive.  In fact I would say that the year the last cohort of girls was born who would not have replacement fertility would be the year recovery became impossible.  But that would be a fool’s wager.  There are no winners at extinction. 

Time is short at best.  If Serbia is to survive, changes must be made. 
Let me know if there is anything more I can do.


M. Linton Herbert MD
This is an open letter to be posted on

There have been 2,809 visitors so far.

Home page.