A LAZY CHAIN DEFINES A CATENARY CURVE. That might be an engineering maxim, or a mathematically minded economist might have said it, and it is a useful trick for designing a pottery kiln, but not a pizza oven. Now comes Elvis, the dog whose companion human, mathematician Timothy J. Pennings, wondered if he has a canine optimal pursuit algorithm.

Elvis doesn't actually do calculus. Nonetheless, Pennings remarked, "Elvis' behavior is an example of the uncanny way in which nature . . . often finds optimal solutions."

"I'd guess that most dogs have the same problem-solving software built in from the factory," he says. My article is just "drawing attention to something that has been in front of us all the while."

Never underestimate the power of adaptation and selection. Sub-optimizing dogs would have starved years ago.