From the book "Financial market and modelisation of stock market's return" - a doctorate thesis only in french - it is said that two researchers have shown that on markets where the number of unlimited life agents is finished rational bubble can only appear if there are entries of new agents. An another researcher has built upon more realistic basis an imbricated generation model with finite horizons and has obtained the interesting result that the condition for a bubble to appear is that the rate growth of population must be superior to the long term real interest rate. This explains the well known fact that stock market follows demography fondamentally (at long term). Also this could explain why futures industry and stock market in general need ... a great number of newbies pigeons - all the more so that real interest rate is high which shows that the interest rate is not neutral in the intensity of the phenomena. P.S. : This for answering the question who are the rabbits : http://www.elitetrader.com/vb/showthread.php?s=&postid=328313#post328313
In fact the origin of interest rate far before Jesus Christ since it has its very root with animals population rate growth : http://viking.som.yale.edu/will/finciv/chapter1.htm#babylon The Idea of Interest What gave the ancient Sumerians the idea of charging each other interest? Linguistic evidence provides a clue. In the Sumerian language, the word for interest, mash, was also the term for calves. In ancient Greek, the word for interest, tokos, also refers to the offspring of cattle. The latin term pecus, or flock, is the root of our word "pecuniary." The Egyptian word for interest, like the Sumerian word, is ms, and means "to give birth." All of these terms point to the derivation of interest rates as the natural multiplication of livestock. If you lend someone a herd of thirty cattle for one year, you expect to be repaid with more than thirty cattle. The herd multiplies -- the herder's wealth has a natural rate of increase equal to the rate of reproduction of his livestock. If cattle were the standard currency, then loans in all comparable commodities would be expected to "give birth" as well. The idea of interest seems to be a natural one for a pastoral society, but not so for other types of economies.