Behavior Quiz: If you put five breeding stallions together in an open pasture, what do you get? A) the Kentucky Derby, minus the jockeys, B) a new pro basketball team, or C) dramatic chaos?

Believe it or not, according to a new study by a Swiss research team, the answer is D) none of the above. In fact, the scientists, led by Sabrina Briefer, DVM, MSc, researcher at the Swiss National Stud in Avenches, found that within a few weeks, study stallions were not only living as a peaceful herd, but were even showing signs of positive social relationships, such as mutual grooming.

"It had a lot to do with hierarchy," Briefer said. "Once that was established, the stallions seemed to know their place and accept it, and then they were fine."

To carry out the test, the five stallions, which had just finished a season at stud, were brought into individual stalls next to each other in the same stable for one week. During that time they were allowed independent time to discover the 11-acre (4.5-hectare) pasture that they would soon be sharing with the other stallions. When the stallions, ranging in age from 9 to 18 years old, were first released together in the pasture, the researchers were ready with equipment to intervene if necessary