Monday, 3 March 2014

The case of Moulay Ismael - fact or fancy

Image courtesy of Wikimedia Commons.
The Moroccan ruler Moulay Isma├»l Ibn Sharif (1634? or 1645? – 1727), also known as Moulay Ismael the Bloodthirsty or the Warrior King, is believed to hold the world record for the highest number of offspring for any man throughout history, but the facts are a matter of some debate. A contemporary report from 1704 records that Moulay had 600 sons by four wives and 500 concubines. Daughters by his four wives were allowed to live, whereas daughters born by his concubines were suffocated by the midwives at birth. This results in approximately 1171 children from 500 women in a reproductive time span of 32 years (25–57). A new scientific paper using computer modelling has attempted to determine whether such a feat was actually possible. Even using more conservative assumptions the authors concluded that the Emperor's reproductive success was plausible, but he would have had to have sex every day for thirty-two years. The authors do not seem to have made any allowances in their simulations for multiple births. They have also not taken into account his reproductive history before he became emperor as they consider that he would probably not have had a comparable harem by then. I'm not aware of any projects focusing on Moroccan Y-chromosome DNA, but it would be very interesting to see if there is a legacy of the emperor's reproductive success in the DNA of living males in Morocco today. If any males are interesting breaking the record, you might like to know that a breeding pool of between 65 and 110 women in your harem leads to the maximum reproductive outcome!

Here is the abstract from the paper:
Textbooks on evolutionary psychology and biology cite the case of the Sharifian Emperor of Morocco, Moulay Ismael the Bloodthirsty (1672–1727) who was supposed to have sired 888 children. This example for male reproduction has been challenged and led to a still unresolved discussion. The scientific debate is shaped by assumptions about reproductive constraints which cannot be tested directly—and the figures used are sometimes arbitrary. Therefore we developed a computer simulation which tests how many copulations per day were necessary to reach the reported reproductive outcome. We based our calculations on a report dating 1704, thus computing whether it was possible to have 600 sons in a reproductive timespan of 32 years. The algorithm is based on three different models of conception and different social and biological constraints. In the first model we used a random mating pool with unrestricted access to females. In the second model we used a restricted harem pool. The results indicate that Moulay Ismael could have achieved this high reproductive success. A comparison of the three conception models highlights the necessity to consider female sexual habits when assessing fertility across the cycle. We also show that the harem size needed is far smaller than the reported numbers.
The scientific paper by Elisabeth Oberzaucher and K Grammer in PLOS ONE (February 14, 2014 DOI: 10.1371/journal.pone.0085292) can be found here.

1 comment:

Anonymous said...

They aren't taking into account having sex multiple times in the same day either . . .