All’s Fair in Love and War, Says Evolution

When I highlighted some great scientific accomplishments in genetics and macroevolution last year in celebration of Darwin Day, I quoted University of California biologist Francisco Ayala who told Smithsonian Magazine, “Darwin didn’t know 99 percent of what we know, but the 1 percent he did know was the most important part.”

And the 1 percent Darwin knew continues to help us explore something we know little about ahead of a holiday that venerates it: love.

Here are five insights on relationships, attraction, and sexuality, thanks to science:

If musicians are the Casanovas of the Homo sapiens, birds and their dinosaur ancestors are the rock stars of the avian and reptilian world.

It’s common knowledge that musicians need not have conventionally attractive physical features to attract sexual partners and mates, and the unassuming male great reed warbler knows this very well. During summer mating seasons, which they spend in Europe and Asia, they sing for as many as twenty-one hours to impress the ladies, and the most talented are able to attract four to five partners in a breeding season. What’s their secret when 20 percent of male warblers sing for weeks with no success? Ecologist Marjorie Sorenson and her team’s observations present evidence that the most attractive warblers rehearse and edit their songs when their on winter holiday in Africa. According to Smithsonian Magazine, “Sorensen and her team then expanded their analysis to include fifty-seven songbird species that migrate from Eurasia to Africa. The ones that spent the most time singing in winter were those in which males produce the most complex breeding songs but have the most drab plumage. For species with flashier feathers and simpler songs, Sorensen says, practice might not be as critical.”

While birds probably didn’t evolve their penchant for song from dinosaurs, it’s possible that some ground nesting birds who dance to woo their mates may be using a technique that’s millions of years old. A study of scrape markings at four Coloradan sites led by paleontologist Martin Lockley suggests that the carnivorous Acrocanthosaurus dinosaur that lived about 110 million years ago engaged in “energetic courtship displays,” just like birds of today.

There’s an evolutionary advantage to the reason why you’re creeped out. There’s also a scientific reason for “resting bitch face.”

The reason why that guy at the bar staring at you seems so creepy is because he doesn’t seem to be blinking or abashed about his behavior, which is out of the norm of social convention. Maybe he doesn’t use any body language or non-verbal communication. We can’t read or predict what he’s going to do. (He’s also giving you the creeps because unwanted sexual interest is perceived as creepy and because both men and women think that men are more likely to be creepy than women.)

Morticians and taxidermists are rated the two of the creepiest professions because what kind of “normal” person would be comfortable or interested in cadaverous things instead of avoiding them? What other out of the norm and importantly, threatening, characteristics might they have? (Clowns, in this survey, were rated the creepiest profession.) Psychology professor Frank McAndrew at Knox College in Illinois led this survey on “what is creepy” and theorizes that we get creeped out because of pareidolia, our inclination to “construe willful agency behind circumstances and seek out patterns in events and visual stimuli.” (This is also why people seek out religion).

Creepy people and creepy situations are perceived as ambiguous and the threat of harm is unpredictable, but the reason why we get creeped out instead of freaking out or terrified is another evolutionary adaptation to converge at social norms: we don’t want to overreact when the clues aren’t clear.

And for those who are concerned that their love is unreciprocated, don’t worry—maybe it’s not that they don’t like you, but their face just looks that way. “Resting bitch face,” a term that describes the one’s neutral facial expression that others perceive as angry or mean, may constitute of a certain set of microexpressions, as determined by FaceReader, software developed by Noldus Information Technology. Scientists Abbe Macbeth and Jason Rogers used FaceReader to analyze faces of celebrities and well-known personas and discovered that those with RBF register expressing 6 percent emotion with most of it being contempt (the average “neutral face” shows 3 percent emotion that consists of sadness, happiness, or anger). Whether these emotions are present or not, it’s clear that some people’s neutral expressions do seem less than friendly—just don’t let that phase you. (If you want to know if you have RBF, find out more at Noldus’s research blog.)

Trust is an important component of any human—or chimpanzee—relationship.

Ever seen those “a good friend will…but a best friend” sayings? The good friend may be nice, but the best friend will stay by your side through riskier occasions. And we’re not the only species who will trust our friends more than nonfriends: researchers in Kenya found that chimpanzees are “much more likely to trust their friends than their nonfriends, choosing the riskier but potentially higher-reward option.” While it may be scary to fall in love and trust someone implicitly, you may be choosing the more fulfilling path.

Love is a battlefield, and sex is an evolutionary arms race.

Human genitalia and animal genitalia—particularly male genitalia—are often the show-stealer, as we are fascinated by phallic diversity, size vs. girth, and the many ritualistic behaviors that accompany sex, but at a recent anatomy symposium, female genitalia were given proper credit for their role in evolving the diversity of penile parts. While humans can invent their own anti-rape devices, it seems that organisms have been developing them for millennia. According to Science, “researchers studying whales, snakes, and other animals are finding that female sex organs have some of the same baroque complexity seen in males. They now see females as active participants in an arms race, likely evolving more complex genitalia to control mating and to create barriers against forced matings—which in turn leads to male countermeasures.”

At the end of the day, nice guys do win.

Let’s end on a good note for heterosexual nice guys—researchers at the University of Worcester conducted an online experiment, recruiting over 200 straight women to rate men’s potential for a long-term relationship based on their photos and descriptions that demonstrated altruism or not. Women chose altruistic men over non-altruistic men for long-term relationships, but were more interested in choosing the self-absorbed man for a one-night stand. Ultimately, you do get a bonus “greater than the sum of the two desirable parts” for being both altruistic and physically attractive. Whether altruism has the same effect in non-heterosexual attraction or for men looking for female partners is yet to be learned.

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