Though monogamous relationships are found in less than three percent of mammalian species, there are a lot of benefits to it (Opie, Atkinson, Dunbar, Shultz). Unlike human relationships, monogamous relationships among mammals in the animal kingdom are not related to romance, but survival of their offspring. One reason why monogamous relationships occur is because females had spread out geographically, prompting males to stay close by to repel competition. Furthermore, a paired relationship would provide their offspring with the greatest chance of survival if both parents cared for them. For example, most newly hatched birds require a large, continuous supply of food only a pair of parents could meet (Campell and Reece).
There are a few major theories on how monogamy evolved in mammals; the one hypothesized by Lukas and Clutton-Brok argues that there absolutely no evidence of infanticide increasing before monogamy, instead, they found that in almost every case, solitary females came before social monogamy. This evidence counters the hypothesis provided by Christopher Opie. He researched how 230 primate species behave, and mapped evolutionary trees for them, which allowed him to create a timeline for certain traits that developed, allowing the transition into monogamous relationships. He found that before social traits associated with monogamy appeared, he saw signs of infanticide by males. Within primates, this is what led to monogamy, but it only developed later. Since primates breast-feed their offspring for a very long time, if the father is not present to defend his offspring, competing males will kill them.
Lukas continues his point by bringing attention to the fact that females spread out to monopolize food. They find fruit that is harder to find, but is higher quality. In turn, this makes it harder for males to keep other males from impregnating females. Since, “males cannot successfully defend more than one female,” they decide that it’s safer to stay close to females, and that is how monogamy occurs.
Though both teams, the different journals, used different methods to form their theories on monogamy, they can both agree on a few facts. Lukas and Clutton-Brock say that species that are monogamous tend to exhibit fewer physical features between the sexes. They are roughly the same weight, size, and live just as long, but that does not include humans. Opie and team agreed by contributing, “Strict monogamy, such as the gibbons, is not what humans do.”
Both articles make strong points about monogamy and how it has evolved over the years, but in the end, The Evolution of Social Monogamy in Mammals by Lukas and Clutton-Brock was more persuasive than Male infanticide leads to social monogamy in primates by Opie, Atkinson, Dunbar, and Shultz. Lukas and Clutton-Brock were able to provide more background and statistical information than provided by Opie, Atkinson, Dunbar, and Shultz. Their journal elaborately walked me through their research methods and thinking process where I could understand what they were thinking and why they were thinking that. Not only were they able to support their theories conceptually, but also statistically as well. They provided many more reasons why monogamy has evolved, for example, it was a contribution of resources/food, protection, ancestral roots, and male dominance.
After reading these articles, I can say that I learned a lot more about monogamy in primates in much more depth than I had ever expected to. It hasn’t changed the way I thought about monogamy, but it provided reasoning for it that I can relate to our human relationships, even though we’re different. It allowed me to understand that there are a lot more reasons why monogamy works for primates and birds. It makes me wonder why other mammals have not yet also adapted into this type of relationship. In my opinion, it’s what works the best- Lukas and Clutton-Brock work proves it to be the best with their statistics.