Biology of Non-Monogamy

The term ethical non-monogamy is starting to become more common in modern society, the idea that you can have more than one sexual or intimate partner and everyone involved knows about each other. For many, this is a radical idea and goes against everything they were taught to believe about what a relationship is supposed to look like. So is this a new phenomenon? We all know that cheating on a partner goes as far back as written history because we have the accounts of royals and commoners alike being unfaithful, but what was going on pre-history? If we want to look at what happened before recorded history we have a couple of options, one is to look at modern day hunter and gatherers and the other is to look at our biology. 

The study of indigenous tribes around the globe has given us some interesting data about how sex and community were tied together. Due to the lack of truly undisturbed tribes by the end of the nineteenth century we have limited examples of daily life before westernization but there were some commonalities. Very rarely was monogamy seen as the only choice, and often the tribes that practiced monogamy had already been visited by missionaries. One of the most common sexual practices was shared paternity, this is the belief that a child could have many fathers. What this means is that if a woman is trying to get pregnant she would sleep with several different men that she picked for positive traits, strength, hunting skill, tool making, kindness, so that the spirit of each would be part of her baby. Not only did they believe that this gave the child an advantage spiritually but it was also practical because each man took responsibility for the child as his own therefore the mother and child had a team to support them. This was not done in secret, each participant had full knowledge of what was going on. These tribes are what in the biological world we call socially sexual, sex was not just reserved for our pair bonded partners but was used as a means of building social cohesion, and we are not the only primates to do this. In fact, nearly all primates are socially sexual.

This brings us to the second of the ways to look back into the distant past, biology. By looking at the biological makeup of a species as well as comparing it to similar species we are able to get a picture of how Homo sapiens lived. Let's look at the biological structures. By analyzing the sexual organs we get a pretty clear picture that we did not evolve as a monogamous species. The clearest sign of this is the human penis. Starting with the testicles, we see that sapiens have large external testicles. For those of us with said testicles, we know that having them hang externally is not always the most convenient or comfortable place for them to be. However, they are there for a reason, to keep them cool. Larger testicles that are kept at a cooler temperature produce larger amounts of healthy sperm. This is why men are told not to wear tight fitting underwear if they are trying to have kids, higher temperatures can cause damage to your little swimmers and even lower your sperm count. What this indicates is that like chimps and bonobos who also have large external testicles, we are prepared for sperm competition. In socially sexual species the males evolve a variety of ways to try to outperform their rivals and pass along their genes. One is strength and volume of their ejaculate. In contrast, let's look at gorillas who live in small groups consisting of one adult male and 3-5 females and their offspring. Because the silverback drives away the male offspring as they reach maturity, there is little to no competition. The result is that a 400 male gorilla has testicles located inside his abdomen and they are about the size of raisins.

Another biological trait to look at is the size and shape of the penis. First, let's talk about shape. The glans or head of the human penis has a distinct mushroom shape, this is also related to sperm competition. The two most common tactics in the competition to pass along genes are, being first to make your deposit, and if you aren't first, removing the other males sperm and replacing it with yours. Our large external testicles take care of being ready to go at any opportunity in hopes of being first, but if we aren't then what? This is where the mushroom cap comes in. The pointed tip makes penetration easier and then on the out stroke the ridge around the head creates a seal and acts as a suction device. As the males strokes repeatedly this suction can pull any other males sperm back and allow the second male to deposit his in front, therefore increasing the odds that the offspring will be his. 

As far as size goes, we need to talk about the ladies. First, we are not talking about the size of our penises compared to other humans, I know this is a topic a lot of guys think about, however, compared to other primates we are very well endowed, regardless of how big you are. Compared to body size sapiens have penises that are longer and thicker than most other primates. This tells us something about the behavior of the females. Studies have shown that the size and shape of the primate penises are directly related to how promiscuous the females are. In species where there is little sperm competition because the females tend to stay with one partner at a time the penises are smaller and less elaborate. In species that engage in socially sexual behavior have penises that are larger and tend to vary more in shape, this is believed to be a mechanism for attracting and pleasuring the female, therefore, increasing the chances of mating. If we go back the silverback gorilla, this theory would suggest that because of their harem social structure, we should see the result in the penis. We do, that same 400 gorilla with the raisin testicles also has a penis the size and shape of a bugle corn chip, triangular and about 1 to 1.5 inches long. 

What this quick look at the biology tells us is that as Homo sapiens we are genetically built to be socially sexual. However, the caveat to that is we no longer live the way we did as we evolved. Our modern culture and beliefs regulate most of what used to be biologically driven, meaning that we decide how we want to live regardless of what our bodies were built for. I am in no way saying monogamy is wrong or that everyone should be sleeping with multiple partners, however, if that is what you choose to do then you have the biological makeup to do it. If for you monogamy is the best option all I ask is that you remember not everyone made that same decision, some of us choose to be ethically non-monogamous and both choices are completely natural.