f there’s an exception to the rule about hunter-gatherers sharing food, Bram Tucker may have found it. Tucker, who last spring completed his Ph.D. working with Bruce Winterhalder and has since been lecturing in the Department of Anthropology, spent several years studying Mikea people of southwestern Madagascar.

"For almost every hunter-gatherer group ever found, the textbooks all say that sharing is the way that they exchange food, and that they do this to reduce risk," Tucker says. "But Mikea almost never share food."

Why not? Tucker offers a possible explanation: "Among most foragers who share food, what they share is large game meat. In Madagascar, the largest game is feral cats. It’s really hard to take a cat and divide it up and share it among the camp. And the Mikea diet is very high in carbohydrates, very low in protein and fat. So when a household does get meat, the family values that meat so much that they can’t stand to part with it."

While Mikea subsist mostly by hunting and gathering, they also work at farming, wage labor, marketing, and herding. As they shift from one occupation to another, they identify with different groups. Within this fluid social structure, people have many potential allies, Tucker says. "So if you’re living in the savanna and it’s really dry there, you can go visit your friends or your kin on the coast and they can accommodate you." For visitors, Mikea will share food, but only for a few days. After that, guests are on their own.

he complex social relations of Mikea correspond to features in their environment. Alliances typically are arranged east and west, Tucker says, because southwestern Madagascar’s microenvironments run north and south. "So if you have friends and allies going east and west, then you have friends in each microenvironment."

Unlike the Peruvians Bruce Winterhalder studied, Mikea don’t scatter their agricultural fields. But they have found various other ways to diversify their food supply and protect themselves from risk. Some Mikea families keep houses in several microenvironments, moving from one to the other seeking sources of income or food. And they hedge their bets with crops, too, planting manioc in case of dry times, corn in case of wet.

Ancestors of today’s Mikea were herders and farmers who did only a little foraging, Tucker explains. From the 17th century through the 19th, they suffered under warring chiefs who were raiding, stealing cattle, and selling children into slavery. Mikea gave up their farms and herds and fled into the forest, where they subsisted primarily by foraging. "So for Mikea, hunting and gathering is a recent adaptation to a political environment," Tucker says.

Having lived with Mikea for as many as 14 months at a time, Tucker made friends and began to discern the subtleties of how his hosts structured their lives. For example, decisions to farm or to forage involved subtle differences in the perception of value and time. For Mikea, the immediate rewards from foraging often assume a higher value than the delayed and uncertain rewards of high-risk agriculture.

"Development people," Tucker says, "often go off to places like Madagascar and say, ‘Hey, why are these Mikea doing this lousy, low-investment agriculture? What they’re doing is irrational and inefficient.’ And then you point out, from an energy perspective, it’s not irrational at all. In fact, it may be very rational. That’s kind of our mission, as human ecologists — to try to understand those other rationalities."