Primate Monogamy

In the study of ecology, biologists have noticed that most species practice promiscuous mating, which does not entail of any long-lasting relationship. Organisms exhibit this type of mating in order to provide for the needs of young. There are two long-lasting reproduction relationships, monogamous and polygamous mating. In monogamous mating, one male strictly sticks to one female in order to reproduce. This is rare among mammals, since less than 3% of all organisms under this classification are involved in monogamous relationships. In polygamous mating, an organism of one sex mates with several of the other sex. This seems to be a more popular practice which results in more offspring. However, why do a small number of mammals practice monogamous mating? Based on what we have learned and discussed, mammals would much rather stick to one mate than risk the chance of not finding another. Males, which are usually the ones which instigate all mating processes, know that they are not guaranteed another mate if they leave the one they currently have. Therefore, some decide to play it safe and simply practice a monogamous relationship. Mammals also decide to partake in monogamous mating to provide for offspring. Yes, the female usually provides offspring with food through lactation, but the male is able to protect females and young, just like lions do themselves. Fathers in monogamous relationships are also able to establish a “certainty of paternity” by guarding their mates, removing sperm from the female reproductive trap before copulation, and replacing other sperm with their own.

The Evolution of Social Monogamy and Male Infanticide Leads to Social Monogamy in Primates argue against each other on a very important topic. D. Lukas in The Evolution of Social Monogamy does not believe that male infanticide is the principal mechanism for the evolution of social monogamy in animals, while the other scientific journal does. However, both journals agree that paternal care only follows social monogamy, it does not precede it. While Christopher Opie, the author of Male Infanticide Leads to Social Monogamy in Primates, argues for high levels of male infanticide, Lukas argues for solitary living as the driving force for monogamous mating. Lukas states that “solitary living appears to have been the ancestral condition for the ancestors of all mammalian orders” which explains for the evolution of monogamous relationships among mammals. Opie on the other hand states that “it is only the presence of infanticide that reliably increases the probability of a shift to social monogamy.” In both scientific articles, Lukas and Opie test a variety of hypothesis which attempt to explain the evolution of monogamy among mammals, only to come to different conclusions. Both authors qualify three proposed hypotheses to explain the evolution of social monogamy: parental care, mate guarding, and infanticide risk.

I personally believe that Lukas was able to make a more compelling argument for solitary living than Opie was able to make for male infanticide. I challenge Opie’s methodology that provided him with results which helped him conclude that infanticide preceded female ranging patterns. I found Lukas’s argument against male infanticide more straightforward and convincing than Opie’s. Lukas states that “the available evidence suggests that male infanticide is unlikely to be the principal mechanism for the evolution of social monogamy in mammals” and then provides evidence which shows that male infanticide is more prevalent in solitary species than socially monogamous species through lactation. He goes on to drive his point home by denouncing an “association between the evolution of social monogamy and lactation durations that exceed gestation.” Lukas provides evidence which completely denounces male infanticide as the force behind social monogamy, while Opie fails to provide enough evidence against Lukas’s claim for female solitary living. I am not convinced that Opie’s methodology is valid enough to conclude that female ranging traits evolved after monogamous mating. A compilation of possible data is not enough to denounce solitary living or parental care.

To be completely honest, I did not have any idea that monogamous mating was so rare among mammals. As a human who will eventually practice monogamy, it is hard to believe that other mammals do not follow this route. Both Opie’s and Lukas’s journals helped me understand social monogamy among primates and among humans. I was able to understand why we follow this practice by being taken into a more in depth explanation of the concept. One of the concepts which I kept referring back to while I read this article was R-selection and K-selection. As I began to build reasons to which would explain monogamy, I also began to see a correlation between monogamy and K-selection. In this type of selections, organisms choose to not reproduce as much offspring, but establish more competitive capabilities. Humans exhibit this type of selection frequently, for we focus our energy on our offspring rather than on our reproductive capabilities. Individuals that are K-selective happen to be large in population size, have a long life span, and are slow to mature. Monogamy seems to fit perfectly with K-selection, and it seems to drive it. Monogamy leads to the parental care of our young, which leads to more adaptive traits among our population. What did surprise me the most was the fact that parental care came after social monogamy. I believed that organisms wanted one mate in order to care for their young and be more involved. After reading both of these articles, I can see that monogamy only results in the “production of high-cost offspring”. Nonetheless, I have been able to tell that social monogamy is indeed a greatly debated topic, for to this day, we do not know what exactly leads to it. We seem to be getting closer to a sure answer every day.

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