Rob is a risk taker—the kind of guy who climbs mountains just because they are there. And he’ll be the first to tell you that he does it for the rush. Kristin is more reserved, but don’t ask her about that, because she’s not a talker. Adrian is always happy; Steve takes offense when none is intended. They all have different personalities.
Psychologists usually define personality in terms of the expression of stable, enduring behavioral patterns. One of the most studied personality traits is shyness. People who are shy when they are young are very likely to be shy for their entire lives.
Every human society is a composite of different personality types. A mix of personalities makes for a more pleasant society, perhaps even a more functional one. A society of pure risk takers probably would not last long, nor would a society composed completely of shy folks.
But human societies are not unique in containing a mixture of different personality types. Of late, evolutionary behaviorists have turned to studying animalities. More and more evidence, from a wide variety of species—cats, dogs, hyenas, and many other critters—suggests that animals within a given population show consistent differences in how they behave, and that these differences often map nicely onto the sorts of patterns we see in humans. But animal behaviorists like me are interested in much more than whether animals and humans show similar animality/personality types. We want to understand the costs and benefits associated with different animal temperaments.
You may have wondered what it means for an orangutan to be a happy-go-lucky sort. Alexander Weiss and his colleagues have. And their sortie into simian bliss has shed new light on animalities. Psychologists have long used a certain questionnaire to measure what they call “subjective well-being” in humans. Trained observers watch someone, looking for signals of positive or negative mood, and they try to gauge how much pleasure the subjects they are watching derive from interacting with others. They note whether the people they are observing are good at achieving their goals. Then they fill out the questionnaire. Weiss and his colleagues took this scale and “orangutanized” it for apes living in zoos. They measured such things as how well the orangutans interacted with one another and with their zookeepers, the frequency of negative versus positive moods displayed, and the animals’ ability to achieve a goal. Over the course of seven years, they measured subjective well-being in 172 orangutans.
They found that if you’re an orangutan, at least an orangutan living in a zoo, you have basically one of two animality types. If you are lucky, you’re an orangutan who scored high on the subjective well-being test. Such individuals were extroverts, interacting often and in positive ways with the other apes, whether their fellow orangutans or their human keepers. Other orangutans scored poorly on the subjective well-being test—they didn’t play well with others. Additional studies showed that these animals displayed unusual “neurotic” behaviors—they seemed uncertain of themselves and distressed by events that do not trouble other orangutans.
Subjective well-being mattered for the orangutans, and it mattered a lot. When Weiss and his team looked at mortality data, they found orangutans that were rated high on subjective well-being measures lived an average of 11 years longer than those who rated low.
But it’s not just our ape kin that have animalities. Pigeons do, too. Pigeon groups are composed of what animal behaviorists call producers and scroungers. Producers find new food, while scroungers hang around producers and parasitize the goodies that producers uncover. Boris Palameta and Louis Lefebvre found that when new flocks of pigeons are formed, only a few birds seem to be producers and the rest just scrounge off their productive group mates. (Sound like anyone you know?) They put 16 birds together in a large aviary that had 48 little test tubes in a row. Only five of the tubes had food, and the pigeons didn’t know which five. In order for a bird to open a tube, it had to learn to peck at a stick in a rubber stopper at the top of the tube; the tube then opened and the food dropped onto the ground and was available to all birds, not only to the bird that solved the test tube problem. Two birds of the 16 learned the task and procured all the food that the group obtained. Every other bird was, well, a leech, and ate only what was uncovered by producers.
Something else caught Palameta and Lefebvre’s attention. Scroungers seemed more interested in where producers were than in what producers did. When the researchers removed the two producers from their group of pigeons, none of the scroungers opened the tubes, even though they had all seen producers do so on many occasions. It was not as if scroungers could open the tubes but opted not to; they had simply never learned how to produce for themselves even though they watched others master the task of finding food.
Again, as with the orangutans, animality type mattered. Being a lazy bum works, but only if you have others in your group to parasitize.
We have to cope with the ups and downs of life. So do rodents. Animal behaviorist Jaap Koolhaas has found two coping styles in these animals—which amount to two different animalities, labeled proactive and reactive.
Proactive animals remove negative stimuli from their environment. For example, if a small electric prod that produces a shock when touched is placed in a mouse’s cage, proactive mice bury the prod, while reactive mice just stay away from it. And if an intruder mouse enters a proactive individual’s cage, the owner responds swiftly and aggressively, attacking the intruder until it hides under any cover available. Reactive mice mostly just try to hide from intruders. Much of how these animals handle stress in their world is determined by their animality. And one nice thing about working with rodents is that you can do breeding experiments. Researchers have selectively bred even more dramatically proactive and even more dramatically reactive mice, establishing a genetic underpinning to animalities.
Let me close the way I’d like to see more stories on animal behavior close—with a quote from Seinfeld. Standing in a liquor store, George stares at a bottle of Wild Turkey bourbon. He gets his species a bit confused, but in a rare moment of introspection, he poses the following series of questions to Kramer: “Do you think chickens have individual personalities? … If you had five chickens together, could you tell them apart by just the way they acted? … ‘Cause if they have personalities, I’m not sure we should be eating them.” I’m not sure we should be eating them either, but I am sure we should be studying them and other animals, and that we should be learning what we can about animalities. Just as personality captures so many interesting components of what makes humans human, animality does likewise for other species. Studying animalities is a powerful way to increase our understanding of how natural selection has shaped the bewildering and beautiful diversity of life we see around us.