In the summer of 1994, TIME magazine emblazoned a striking image of a broken wedding band on its cover, posing the question of the existence of a genetic base to marital infidelity (Infidelity Is It In Our Genes?). Inside, a lengthy article examined scientific facts and theories relative to the evolution of monogamy, and examined their relevance in explaining… or perhaps justifying, the social organization of reproduction amongst humans.
For over a century, monogamy has both fascinated and thwarted behavioral biologists. As the German ethologists Wickler and Seibt pointed out as early as 1983, there are two main reasons for all the attention paid to monogamy. First of all, monogamy was considered, at least by Western civilization, as the ideal family structure for human beings. This focussed particular attention on any similar system in the animal world. Secondly, for most species, the sexes differ in both the quantity and the size of their sexual cells (gametes) as well as in the costs associated with their production. Among species described as anisogamous, males, since they produce a large number of gametes at a low cost, are supposed to maximize their reproductive potential by multiplying reproductive partners, which corresponds to polygamy. Monogamy would therefore be counter-selected in males. From this point of view, monogamy is considered as a system of reproduction in the genetic sense. The more commonly used meaning of the term would refer to a mutually exclusive sexual relationship as the main characteristic of monogamy. Yet monogamy can also be seen as a type of social organization, i.e. in the terminology used in behavioral ecology, a mating pattern. For two individuals of the opposite sex, the stress is put on the importance of a long-term relationship, with the possibility of sharing parental responsibility. Because of exacerbated anthropocentrism, the two aspects of monogamy, sexual faithfulness and social ties, are often perceived as being necessarily associated. This “moral” vision of monogamy doesn’t seem to withstand the analysis of its biological reality, as recent works published in the field of behavioral ecology would attest.
A magnificently documented overview that presents the multiple guises in which monogamy is found in the animal kingdom, including among humans, and explains how this mating pattern has managed to evolve many times over the course of living history.