A clear exit line, and, speaking of grants, I still had half those hair-bobbing clippings to sort into piles before I went home. But I was still trying to put my finger on what it was that was so unusual about him. I followed him through the maze of stuff.

“Is Flip responsible for this?” I said, squeezing between two stacks of boxes.

“No,” he said. “I’m setting up my new project.” He stepped over a tangle of cords.

“Which is?” I brushed aside a hanging plastic net.

“Information diffusion.” He opened a door and stepped outside onto a porch. “It should keep cold enough out here,” he said, setting it down.

“Definitely,” I said, hugging my arms against a chilly October wind. The porch faced a large, enclosed paddock, fenced in on all sides by high walls and overhead with wire netting. There was a gate at the back.

“It’s used for large-animal experiments,” Dr. O’Reilly said. “I’d hoped I’d have the monkeys by July so they could be outside, but the paperwork’s taken longer than I expected.”

“Monkeys?”

“The project’s studying information diffusion patterns in a troop of macaques. You teach a new skill to one of the macaques and then document its spread through the troop. I’m working with the rate of utilitarian versus nonutilitarian skills. I teach one of the macaques a nonutilitarian skill with a low ability threshold and multiple skill levels—”

“Like the Hula Hoop,” I said.

He set the box down just outside the door and stood up. “The Hula Hoop?”

“The Hula Hoop, miniature golf, the twist. All fads have a low ability threshold. That’s why you never see speed chess becoming a fad. Or fencing.”