Walter SCHEIDEL   How to be Incestuous: The Emotional Context of Sibling Marriage in Roman Egypt

 

 

The census returns of Middle Egypt offer unequivocal and quantifiable evidence for the widespread practice of full brother-sister marriage among monogamous commoners in the second and third centuries AD. Attempts to explain this custom have traditionally been limited to the question of the underlying motivation, but in the absence of pertinent contextual information have thus far proven unsuccessful. However, the feasibility of establishing sibling unions for reproductive purposes likewise requires examination: after all, it is now well established that no amount of cultural indoctrination can fully offset innate aversion to mature incestuous relationships. A combination of papyrological data, historical sources from other periods, and scientific experiments can shed new light on an otherwise intractable conundrum. For the first time, this paper aims to identify the various factors that facilitated or inhibited sibling marriage in Egyptian households. Drawing on the census returns as well as other papyrological material such as wetnursing contracts, it becomes possible to reconcile the documented custom of Roman Egyptian sibling marriage with predictions generated by comparative data (esp. from Taiwan) and studies of animal behavior.

First of all, the census returns show that a significant proportion of sibling spouses were too far apart in age to have been emotionally conditioned against incestuous relationships. Secondly, some of the Egyptian sibling couples who were close in age experienced high rates of marital separation, as predicted by comparative evidence. And finally, some of the birth intervals in incestuous families attested in the same group of documents point to a significant incidence of wetnursing. In keeping with the results of ongoing studies of the olfactory determinants of mate choice in mammals that show that cross-fostering interferes with instinctual imprinting mechanisms that trigger aversion against incestuous relationships, similar responses may also be postulated for humans: and indeed, very recent experiments have lent support to the notion that human mate choice is influenced by the same mechanisms that have been observed in animal probands. This fusion of findings and perspectives derived from different disciplines now enables us to accommodate and interpret the papyrological evidence of sibling marriage within a broader interdisciplinary framework, and permits us to answer the question of how sibling marriage was feasible and could even result in substantial progeny.