Social Monogamy in Mammals

We currently believe monogamous relationships exist in mammals due to the need of parental care. Some relationships yield offspring that require more food than can be provided by a single parent. As a result, a male will stay and help take care of the offspring as opposed to searching for another mate.

In Male infanticide leads to social monogamy in primates, Opie (et al.) suggest that social monogamy in mammals is a result of high rates of male infanticide. They tested to see if there was a relation between the presence of three different traits (parental care, female ranging patterns, and male infanticide) and social monogamy. Of the three traits tested, groups that exhibited social monogamy consistently exhibited low rates of male infanticide as shown by figure 1c. This supports the idea that there is a correlation between male infanticide and social monogamy. In The Evolution of Social Monogamy in Mammals, Lukas (et al.) say that “social monogamy is derived from an ancestral state in which females are solitary and male ranges overlap those of several females.” This living arrangement constitutes intense feeding competition and intolerance between females, and low female densities. As a result, males tend to stay with the females in order to protect them from other potential mates. Furthermore, Lukas (et al.) also suggest that there does not appear to be an association between male infanticide and social monogamy. They attribute this conclusion to the differences in population size between their experiments and those done before them, saying that, “our larger sample size also allowed us to assess whether changes in population density preceded transitions to social mongamy.”

I believe Lukas (et al.) provided a more convincing scientific argument because of their consistent use of data to support their hypotheses. For example, when talking about their review of social monogamy and male infanticide, they say “although the prevalence of male infanticide is lower among socially monogamous species (4 of 47 species, 9%) than among solitary species (24 of 88 species, 27%…) this difference does not appear to be a conswquence of a direct association between social monogamy and male infanticide…” where they go on further to explain that another analysis of the data “suggest an independent evolution of the two traits.” Their use of relevant data throughout the article supports their claims.

Yes, these articles have changed my understanding of monogamy in primates. Before, I thought monogamy was simply a result of the need for extra parental care for offspring. Both of these articles delved deeper into the idea of the evolution of social monogamy and had a lot of supporting evidence for the claims they raised. The most surprising piece of information I read came from the article The Evolution of Social Monogamy in Mammals where Lukas (et al.) mention that fruit is the main part of the diet for 91% of socially monogamous primates as opposed to the 28% of solitary primates. Furthermore, they go on to say that foods of low nutritional value are included in the diet of 93% of solitary primates as opposed to the 39% of socially monogamous primates. This correlation between the diets of the primates and their mating relationships was intriguing and the writers’ use of relevant data further supports the idea that there is an association between social monogamy and low-density resources.

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