Why Science Needs More Sex

In March 2013, Yale University biologist Patricia Brennan, who studies the evolution of birds’ reproductive organs, found herself in the path of a two-week media cyclone. Brennan had secured a $390,000 National Science Foundation grant for her work on duck genitalia. Conservative news site CNSNews.com found out about this and ran a story on it, which sparked nation-wide outrage (quickly dubbed “Duckpenisgate”) at the spending of tax dollars on research as frivolous as studying the nether regions of waterfowl.

We genital researchers are used to getting giggly or derisive responses when we try to explain our work. It has been like that ever since this particular branch of evolutionary biology was kick-started, back in 1979. In that year, in the journal Science, Brown University’s Jonathan Waage reported that male damselflies use their penis not just to squirt sperm into the female’s vagina, but also to scrape out any remaining sperm of her previous trysts. When I interviewed Waage for my book Nature’s Nether Regions, he recalled that one magazine covered the news with a derogatory headline like, “University Egghead Wastes Taxpayers’ Money Studying Dragonfly Sex”.

The egghead headline and Duckpenisgate bracket three and a half decades during which the study of the evolution of penises, vaginas, and their equivalents throughout the animal kingdom has matured into a solid biological discipline, with hundreds of my fellow scientists worldwide working on it. However, if we are to believe our vociferous critics, we have all been sidetracked into a perversion of publicly funded science, following our own deviant fascinations with the sordid sex lives of inconsequential creepy-crawlies, rather than pursuing research that benefits society.

I could of course retort by pointing out that our field has, on occasion, yielded direct applications. Artificial insemination in livestock has been improved by more effectively-shaped pipettes, and certain gynecological problems can also be understood if we take an evolutionary view.

Such practical spin-offs are all-too-often paraded by basic science as a justification, or even a motivation for its existence. But deep down we all know this to be only part of the story. The desire to understand nature, and the great satisfaction when we succeed, is what really drives us genitalia researchers, and technological or medical applications of our research are little more than a beneficial side-effect.

But that is not to say that our work is a solipsistic exercise for evolutionary biologists only. I think basic science should be mentioned in the same vein as art, music, or top-class sports, which also serve no practical purpose but provide entertainment to the rest of humankind. Evolutionary biologists do the hard scientific labor that leads to the discoveries that allow us to tell true tales about the way nature works. Billions of people watch nature documentaries about amazing wildlife in far-away corners of the globe. But the facts dished out are not discovered by their khaki-clad presenters. Instead, every minute of footage required a dedicated, publicly-funded biologist, sometime, somewhere, doing the painstaking basic research and furnishing a previously unknown plant or animal with its fifteen minutes of National Geographic fame.

And if anything about nature is entertaining, it should be all the weird and wonderful ways in which animals have sex. The list of mind-bending facts is endless.

Think snails that impale one another with hormone-laced daggers; she-spiders that force their partners to four hours of foreplay and galago ladies that demand equally drawn-out afterplay; slugs with (literally) yard-long penises that take a whole night to erect; a rove beetle with a coiled-up vagina three times longer than her body; insect semen that leaches holes in the vagina wall, makes a female frigid, congeals into a cement-like plug, or otherwise misbehaves…

These snippets of the outlandish sexual habits of many animals are already highly entertaining in themselves and make good party stories, if nothing else. But they become even more fascinating when they are strung together into a rosary in veneration of evolution’s greatest feats.

Evolution, after all, is all about reproduction: if you’re better at it, you leave more descendants, who inherit your DNA with its superior reproductive abilities, and go on to be successful procreators themselves. All that survival of the fittest stuff is fine, but if you really want to be an evolutionary success, then invest in being better at sex. That is why the evolution of animal genitalia progresses at such a breakneck speed, causing even the most similar species to have wildly different boy and girl bits.

In fact, the evolution of reproductive plumbing is being pushed along even more urgently by a second engine: the conflict between the sexes. Being good at sex — evolutionarily speaking — for a female means choosing wisely from among the available sperm donors. But being good at sex as a male usually means making sure that as many females as possible choose you as their exclusive sperm donor.

Such a conflict of interest pervades the evolution of reproductive organs in animals. But not only in animals: we humans fit right in. Above, I made the claim that gynecological problems can be understood if we take an evolutionary view. For example, scientists have discovered that preeclampsia, a dangerous inflammation in pregnant women—essentially an allergic reaction of the mother’s body to her own fetus —can be reduced by regular exposure of the woman to semen of her baby’s father, either by unprotected vaginal sex or via oral sex. The evolutionary interpretation of this curious medication? Proteins in semen have evolved to take control of the woman’s immune system and protect the father’s interests by suppressing the allergic reaction — even if it were healthier for the mother’s body to abort an overdemanding fetus.

Another gynecological problem are so-called ectopic pregnancies. Sometimes an embryo will implant itself outside of the uterus — for example in the fallopian tube, or even inside the ovaries themselves. It turns out that some of these pregnancies are caused by rogue sperm that do not stay within the legitimate confines of vagina and uterus, but wiggle their way through organ walls and go cross-country, as it were, through the woman’s abdomen, looking for fertilizable eggs.

Such all-terrain sperm are to be expected, and, in fact, similar sperm behavior is found all across the animal world. Again, the problem can be understood if we see that evolution will smile on sperm that do not let themselves be restricted by the boundaries imposed by the female. Such new and refreshing ways of viewing human reproduction can only be achieved thanks to decades of trying to understand animal sex. Populist media may balk at spending public money on such studies. But the field has not only given us the greatest stories from the Kama Sutra of creepy-crawlies, it has also paved the way for gynecologists, urologists, and evolutionary biologists to sit down and draft a research program to gain a deeper understanding of human sexuality and reproduction. Nothing perverse about that.

Menno Schilthuizen is an ecologist and evolutionary biologist based at Naturalis Biodiversity Center in Leiden, the Netherlands, and is the author of Nature’s Nether Regions: What the Sex Lives of Bugs, Birds, and Beasts Tell Us About Evolution, Biodiversity, and Ourselves.