Nowadays, humans are pretty set in our monogamous ways. But do you ever wonder why most people don’t have more than one partner at a time?
For some males, polygamy actually offers profound advantages. For instance, it ensures that their offspring inherit quality genes.
After all, men can father more children by mating with multiple partners, and polygamy allows women to team up to share the most appealing men, instead of being stuck with the second-best options. This type of behavior can be seen in the animal kingdom, like in the case of Elephant Seals who engage in massive tournaments known as leks.
In these competitions, the males fight each other one at a time, with the winning male mating with the surrounding females, who in turn produce children with his high-quality genes.
In humans, the same behavior can be observed in societies stratified by class. Just take the Kenyan Kipsigis. The women of this tribe prefer to be the third wife of a rich man rather than the sole wife of a poor man.
And men aren’t the only ones who practice polygamy – it’s just that the sex with less responsibility in child-rearing is more likely to have a greater number of partners. For instance, in the case of a bird called the phalarope, the smaller males tend to the eggs while the larger females enjoy polygamous relationships.
However, while polygamy can offer some benefits, monogamy will always prevail. This is due to the monogamy threshold, which is reached when there are too many females mating with just one male.
In cases like these, lots of males are left without mates. For these males, and for the less-favored females, it then becomes beneficial to practice monogamy. By mating with just one female, and helping her care for her young, these males can guarantee to pass their genes on to at least one descendant.
Monogamy can also be observed in species like the albatross, the females of which benefit more from parental support than from the genetic benefits of polygamy.
Most legal systems now prohibit polygamy, and such a practice probably isn’t in the best interests of your average guy. But when it comes to evolution, which approach is more advantageous for women?