In a world so thoroughly reshaped by human hands, animals often bump into novel ecological conditions — problems evolution didn’t prepare them for. Plastic items look like food, but they’re indigestible; artificial lights look like stars, but they’re useless in navigation; dead logs look like prime real estate, but they’re often bound for the woodchipper. Natural selection couldn’t foresee all these deadly new surprises, known as “evolutionary traps,” and thus, animals lack the behavioral tools to handle them.
Nature is, of course, always weeding out individuals whose behavior isn’t well-calibrated — the nocturnal possum that comes out an hour early and exposes itself to predators, for example. What’s different about evolutionary traps (and what makes them so dangerous) is that when an animal falls into one, its behavior “is actually perfectly miscalibrated,” says Bruce Robertson, an associate professor of biology at Bard College. “They’re preferring the worst possible thing,” like a possum that whoops in open fields all afternoon.
With enough time and genetic variation, any species can hypothetically escape these pitfalls by evolving better behaviors. But given the breakneck pace of environmental change in the Anthropocene, many can’t adapt fast enough. “Traps will cycle populations toward extinction extremely rapidly,” Robertson says. “They’re like demographic black holes.”
Animals of all kinds, from beetles to birds, are bedeviled by evolutionary traps. Here are some of the strangest and most troubling, along with a few hopeful reminders that we can often undo the damage — at least when we act before it’s too late.
