LIKE many New York bachelors, John Durant tries to keep his apartment presentable — just in case he should ever bring home a future Mrs. Durant. He shares the fifth-floor walk-up with three of his buddies, but the place is tidy and he never forgets to water the plants.

The one thing that Mr. Durant worries might spook a female guest is his most recent purchase: a three-foot-tall refrigerated meat locker that sits in a corner of his living room. That is where he keeps his organ meat and deer ribs.

Mr. Durant, 26, who works in online advertising, is part of a small New York subculture whose members seek good health through a selective return to the habits of their Paleolithic ancestors.

Or as he and some of his friends describe themselves, they are cavemen.

The caveman lifestyle, in Mr. Durant’s interpretation, involves eating large quantities of meat and then fasting between meals to approximate the lean times that his distant ancestors faced between hunts. Vegetables and fruit are fine, but he avoids foods like bread that were unavailable before the invention of agriculture. Mr. Durant believes the human body evolved for a hunter-gatherer lifestyle, and his goal is to wean himself off what he sees as many millenniums of bad habits.