To play, and therefore to mate
Ever since Darwin fingered natural and artificial selection as the driving forces behind evolution, scientists have wondered how our mate choices affect our species’ evolution.
After all, we typically judge mates by appearance, health, abilities, wealth and behavior. And to the extent that these traits are genetic, they should become more prevalent as time passes.
Now we hear of a study showing that both genders place great importance on “playful” behaviors — being able to play, laugh and enjoy life.
Why? As a first guess, women may find playful males less threatening to themselves and their children. Men may link playfulness to youthfulness — and hence the ability to make children.
In the grim spreadsheet of evolution, genetic traits — both structures and behaviors — that are “selected for” become more common in subsequent generations. Traits that are “selected against” grow scarce or get chucked into the trashcan of history. So just as the aggressive wolf underwent selection to became the tame dog we know and love, our mates choices affect the character of our children.
Who do you love?
To investigate the role of playfulness in human evolution, Garry Chick, a professor of recreation, park and tourism at Penn State University asked 254 undergraduates which characteristics they would choose in a long-term mate. The survey was based on an influential 1989 study, which offered traits such as “kind and understanding,” “good earning capacity,” “intelligent,” “good heredity,” and “creative.”
In the rerun, Chick, Colleen Yarnel and Andrew Purrington inserted three new characteristics: “playful,” “sense of humor,” and “fun loving.” Their additions were popular: each of them ranked in the top five of the 15 listed traits, and “sense of humor” ranked first overall.
“To be honest, this was surprising,” says Chick. “Not about the sense of humor; there’s been a fair amount of recent research on it.” But to have all three embodiments of “playfulness” highly ranked by both sexes “was an indication that it’s a very desirable trait in other people.”
The question was worded in terms of a “long-term mate, not a one-night stand,” says Chick. “A couple of woman students said they like bad boys, but for a long-term relationship, they don’t want a bad boy.”
Darn that dream
But from the perspective of natural selection, “and this is recognized by all involved in the evolution of play; [adult play] should not exist, it makes no sense, it uses up energy that could be put to better use.”
And some forms of adult play, like rock climbing, football, biking and cheeserolling, are downright dangerous, Chick adds.
Although play is difficult to define, adults in many species can be enticed to play by young scamps. But play between adults only appears among people, dogs and bonobo monkeys.
The study rests on the assumption that some behaviors have genetic influences, and although it’s possible to get arm-wavingly broad by claiming that genes influence everything we do, there is good evidence that genes affect behavior. Twins separated at birth show many parallel behaviors.
The way you do the things you do
The choices we make during mating, Chick says, are an example of “self-selection. It’s the idea that we see attractive features in other people, we find them enjoyable, and therefore, those are the people we want to make babies with.”
These inclinations would not have to operate consciously in order to be powerful, he says. Nor would they need to rule every time. Experiments show that behavior can change rapidly over the generations. A Russian project, for example, used selective breeding to change the silver fox into a dog-like pet. After only 10 generations, 18 percent of the foxes were extremely tame.
“You don’t need very much change,” says Chick. “The fox study… suggests that this particular behavior [aggressiveness toward people] clearly has a genetic component, and they were able to ease it out by artificial selection.”
I fall in love too easily
Admittedly, the study did not look at behavior. “These are just stated preferences, it’s not a proof,” Chick says. Chick admits that while college students are the cheapest, most available audience for social and psychological research, there are legitimate questions about how well they represent the broader society.
Although they could be particularly suitable for a study of mating, Charles Snowdon, a professor of psychology at University of Wisconsin-Madison and an expert on primate behavior, says, “It is not clear that college students really ‘know’ what to look for in a long term relationship. I’d prefer to see this complemented by a study of an older population, one where decisions about long term relationship and with whom one wants to share child–rearing become more salient.”
Chick suspects that women find playfulness to be a signal for non-aggressiveness, while men find it denoting youthfulness and reproductive capacity. But “we never tested that question directly,” he says.
Alternatively, Snowdon suggests, “Playfulness is a sign that the partner will not be boring. If we are to live with someone in a monogamous relationship for a long time, we humans with big brains and considerable intelligence are more likely to stay with a partner who does not bore us. Since children do much better in life (economically and psychologically) with two parents than with one, then having a partner one will continue to enjoy and share activities with over a long time span will lead to more successful child-rearing.”
In any case, that would also tend to promote playfulness in the next generation.
We like that.
Next up, Chick says, is a look at how well expressed mate choices line up with real mate choices, again in college students.
— David J. Tenenbaum
Terry Devitt, editor; S.V. Medaris, designer/illustrator; Molly Simis, project assistant; David J. Tenenbaum, feature writer; Amy Toburen, content development executive
- Play and Mate Preference: Testing the Signal Theory of Adult Playfulness, Garry Chick et al, American Journal of Play, volume 4, number 4, 2012. ↩
- The play of the bonobo. ↩
- Evolution 101: Sexual selection ↩
- A keynote lecture by Garry Chick: What is Play For? Sexual Selection and the Evolution of Play (.pdf) ↩
- Russian silver fox study ↩
- Twin studies overview ↩