Charles Darwin and Aristotle walk into a bar and order martinis. Aristotle’s drink comes first and he takes a sip. “Bleh,” he grimaces. “It tastes all wrong.” The bartender apologizes that the proportions of gin and vermouth were slightly off and quickly corrects them.
Then Darwin’s martini arrives and it’s a sight to see. It contains four olives, a lemon twist, an onion, and two slices of cucumber. And floating on the surface is a dead fly. Darwin downs the drink in one gulp. “Ugh! How can you drink that shit?” exclaims Aristotle in disgust. “Won’t it make you sick?” Darwin shrugs and replies, “I’ll survive.”
This joke embodies the theories of two famous thinkers. Aristotle organized nature into a strict linear order of perfect, unchanging forms, with humans at the far end. Any deviation from a form was, like Aristotle’s martini, an error. Darwin, on the other hand, saw nature as a vast population of diverse individuals, no two the same. Variation was normal, not an error, and necessary for the survival of the species.
Darwin’s viewpoint is known as population thinking. Any description of a species, to Darwin, is at best a statistical summary that applies to no individual.
The theory of constructed emotion, described in my book, How Emotions are Made: The Secret Life of the Brain, is an evolutionary theory rooted in population thinking. In every waking moment, your brain activity is a storm of predictions as your brain tries to guess what’s coming in the next moment. These predictions, which cascade throughout your brain, compete as the best match for the sensory input from your body and the world. It’s like natural selection on a millisecond scale.
For example, suppose you’re at the bar with Aristotle and Darwin and look up at the bartender, who smiles at you. From your vast set of past experiences (both inside and outside of bars), your brain issues a slew of competing predictions of what that smile means and what will happen next. The smile could mean happiness of course, based on the many times you’ve made and seen happy smiles, which might lead your brain to predict a friendly “Hello.” Or it could be a crazed smile of a madman, or a smile of fear that you’ve experienced on roller coasters, or even the smile made by Kaa, the snake from Disney’s Jungle Book, when he wants to eat someone. Each of these predictions leads your brain to anticipate a different outcome. In other words, your concept of “Smile” is a vast population of diverse instances, each associated with different causes, consequences, and surrounding context. That’s population thinking. In the blink of an eye, your brain winnows down all these possibilities to one that best fits the context. The winning instance then drives your next action and becomes your experience.
Darwin would feel at home with this description of your brain’s conceptual system, whereas Aristotle would probably argue that there’s one essential concept for “Smile,” and any variations are erroneous.
Remember this the next time a bartender serves you an oddly mixed drink. It might seem wrong to you, but maybe it’s just better suited to its environment.