Building a kindler, gentler chicken.

• Position: Chicken breeding

At 24 years and still going, it is the Eveready bunny of selective breeding experiments. Tiny red flour beetles, each one-eighth of an inch long, were put in a plastic box full of flour and allowed to thrive. After one generation of breeding, two lines were developed, with the largest beetles saved in one box and the smallest in another. Each month, the scientists picked the top performers from each family--one line of beetles growing bigger, the other shrinking smaller.

Approximately 260 generations later, the largest beetles are the size of houseflies, and the smallest are difficult to see with the naked eye. "It's the equivalent of breeding a 10-pound dog up to the size of a 200-pound pig and down to the size of a two-pound chihuahua," explains Bill Muir, a Purdue University population geneticist. "What is the limit of selection? That's what we're trying to find out. As long as the beetles keep growing larger and smaller, the experiment will continue."

Population genetics dates back to the early theories of Charles Darwin. The science has helped explain those cases of evolution where classic Darwinian theory alone doesn't offer an explanation. "Look at the honeybees. If survival of the fittest were all that applied, we wouldn't have hives; we would have one large, nasty bumblebee. But that's not the case. We theorize it was group selection that brought about social insects--it was the survival of the hive, or nothing. Those that got along survived."

After 12 years of concentrated effort, Muir successfully has applied that theory to breed a kinder, gentler chicken that coexists peacefully with other chickens. Descendants of aggressive jungle fowl which were extremely territorial, chickens have been domesticated to the point where they will lay eggs almost every day and tolerate having other birds nearby. However, they still are fiercely competitive for food and water, and, if they detect weakness in another fowl, will take violent advantage. The ancient system of a pecking order can mean death for the weaker bird.

Since most commercial poultry are kept in colony cages of six-nine birds, mortality and injury are of concern to producers and animal welfare advocates. Most producers attempt to manage the competition and aggression, Muir points out. "Birds are beak-trimmed to reduce cannibalization, and lights are kept low so they don't see injuries on other birds." A red spot of...