When Animals Are Covered in Semen

Science never seemed so much fun!

Creative Commons photo by Tim Ellis, via Flickr

Evolutionary biology can change the way we look at how organisms function as part of the larger world. The contributions of genetics to the medical field have been immeasurable, and…

No one cares.

Science has a reputation for being dry, mechanical, difficult, and encompassing of many other qualities that would otherwise characterize an unsatisfactory lover. This unfair and blatantly incorrect eschewal of science must be corrected — scientists like to have fun, too, especially evolutionary biologists. What else could Darwin have stored in that monstrous beard but years of difficultly acquired fun facts?

While there are many who take these fun facts as serious research enterprises, scholars outside of behavioral biology might not understand why a biologist would take such a vivid interest in the time it takes rats to get an erection. Fair enough. But consider the following anecdote: bonobos (often referred to as pygmy chimpanzees and our closest relatives along with the chimp) have sex so often that male bonobos lose their hair below their waist. This hair loss is due primarily to the fact that the hair is irritated by the constant smattering of ejaculate that covers the bottom half of these free-loving creatures. While one could argue that this phenomenon is interesting enough on its own, it also gives a picture of what bonobo social life is like. Bonobos have sex with everyone, all the time. While they occasionally fight with other groups, they often welcome them into their community with a giant intergroup orgy. Homosexual sex is frequent in bonobos and is an important social tactic for females, who form strong bonds with each other and protect themselves against male aggression (which is frequent and extreme in their cousins, the chimpanzees, who are not female-bonded). In part because female bonobos can fight back, the rewards of aggression for the males decrease and the group becomes more peaceful. Not only is this an interesting behavioral strategy, but is also relevant to a possible comparative perspective with humans, perhaps even in terms of why homosexuality evolved (which is inarguably relevant to many different schools of thought).

That’s just the beginning of studying the scientific aspects of sex. Yes, sex is fun, it feels good, and it’s worth spending a week talking about. But it may surprise some just how important sex is. There’s a reason Human Evolutionary Biology concentrators (shameless concentration plug) hear about testicles on a weekly basis, read papers about the adaptive purposes of the clitoris, and have slides in their lectures dedicated to pictures of Kim Kardashian — that woman screams fertility; Kris Humphries is a fool. Sex is the crucial foundation of all of evolution, sparking not only all animals’ body shapes and sizes but also their social structures and behaviors. Sex is what made all of the creatures that exist here on Earth what they are today, all in individual encounters that most likely took far less than seven days (unless some organism had unbelievable stamina). We animals owe our very design to sex.

Doing the nasty is really what evolution is all about. In simplified terms, natural selection proposes that those individuals who are the best adapted to their environment, or the “fittest,” will have the most babies and thus the next generation will possess more of the genes and related characteristics of those individuals than those losers who didn’t get any.

For example, the females of some species of guppies are attracted to the most brightly colored (fittest) males, those who flash their sexy tails along the River, turning their heads to catch the glance of breathless observers as they paddle through the water. When the lady guppies see that neon flash of manliness, they can’t help but give themselves to him. A few clutches of eggs later, there are proportionately more colorful males in the population. From an evolutionary perspective, our purpose in life is to screw to the best of our abilities and with the sexiest mates. The reason females find males sexy (and vice versa) is because those qualities supposedly reflect an individual’s genetic quality, and thus what they can contribute to the genetic make-up of an offspring.

To be accurate, our goal may be more about getting pregnant than getting it on, but wake up and smell the bathroom floor — we’re not sponges. We have to do ‘”it” to get the offspring to whom we devote our entire behavioral repertoire to produce. Even though we giggle bashfully when someone says “scrotum,” gasp at nip slips, and gag at the thought of a website devoted to pictures of other students’ genitalia (but no, really, who started that?) we’re designed to get busy. Humans are no exception to this elemental rule of biology: even though we can only be impregnated for part of our cycle, we are continuously sexually attractive and receptive to intercourse. Selection has acted upon females to exhibit signs of fecundity (ability to become pregnant) throughout their cycle. If it hadn’t, our boobs would probably deflate every month. Even many of those things one might attribute to culture, like men buying swanky cars and women wearing low-cut dresses, can be traced back to biologically adaptive behaviors that increase the likelihood of reproduction.

If this all seems heteronormative, it isn’t, because science relies on statistical data rather than subjective categorizations of what is normal and what is not. It’s true that heterosexuality plays the biggest part in how sex shapes our society; only a sperm and an egg can make a baby, and natural selection acts via reproduction. However, there are many discussions as to the biological explanations, both adaptive and developmental, of homosexuality. A behavior that prohibits one’s own reproduction (not via sterility, but rather the exclusion of conceptive sex) does seem odd from an evolutionary perspective, but the fact that homosexuality has existed for so long and remains a measurable percentage of the human population means that it must have some sort of biological correlate.

Mentioned earlier in this article are the social benefits of homosexual sex in bonobos, but the hypothesis could also be applied to humans. It is possible that homosexual relationships served to change one or both of the participants’ statuses within stratified societies or to form partnerships across family groups. Further support for the biological aspects of homosexuality comes from the fact that homosexuality is essentially the same as heterosexuality, but with different targets of attraction. Homosexual men retain the same behavioral repertoire as heterosexual men, exhibiting higher interest in short-term sexual relationships than both homosexual and heterosexual women (males are hypothesized to have a greater interest in short term matings because they need only to mate to produce an offspring, rather than carry and care for the child like females of most species. However, it is not this simple in humans).

We humans can’t help but be fascinated by sex.  Sex is not only what fuels our evolutionary design, but is also what has shaped those cultural and social practices we humans find so important, whether they affect us negatively or positively. Because we operate under the same selective rules as all other species, we are hardwired to pay attention to sex. Sometimes it may be unconscious, but sexual desire is one of our strongest drives; no one can deny the deep influence of sex on an individual’s behavior. This wiring leads those curious about why humans are the way they are to investigate how sexual behavior really functions, and how that neurological, endocrinological, ecological, psychological, and anatomical data influences humanity as a collective whole.

While it might be disheartening to know that there’s not much separating your one-night stand from the behavior of a couple of bonobos in heat, at the end of the day you were born an animal — not an amoeba — and you might as well take advantage of that.

Christine Wolfe ’14 (crwolfe@college) knows that some categorize amoebae as animals rather than protists, but the point is that they’re asexual and we should feel bad for them. So deal. 

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