Anyone who needs proof that tough guys don't always get the girl ought to spend some time with the blue monkeys of Kenya.

Male monkeys fight a lot, and anthropologists often contend that their attempts to gain dominance in a group are really efforts to win first rights to females that happen to be among them.

But after years spent in Kenya watching the sexual habits of the blue monkey, Thelma Rowell, professor of zoology at the University of California at Berkeley, has some other ideas.

In a recent talk at Berkeley's Institute of Human Origins, she reported that the dominant male does not necessarily have exclusive sexual access to females around him, as many had assumed.

She noted that winners of fights might have a slight edge on mating -- among 40 observations, 26 of the winners copulated within 15 minutes of their victories. But, she added, females are just as likely to sneak into the jungle to mate with males from outside the group.

Her findings may have interesting implications for widely accepted theories about the way primates relate sexually to each other when in groups. For years, it has been assumed that one reason male monkeys fight is to enable the strongest to pass his genes along to the next generation.

While the strongest blues do get to pass their genes along, weaker blues also appear to be able to do so.

Blue monkeys live in harems, one male surrounded by many females. The dominant males usually stay in charge for less than two years, and they spend much of their time attempting to chase off the approaches of other males.

Rowell and her colleagues found no correlation between winning fights and getting the best possible sexual access to female monkeys.

Most adult blues spend much of their lives as outsiders, living alone in the forest. But Rowell found that these loners are actually well tuned to the sexual cycles of female monkeys around them. If several females become sexually receptive at the same time, the outsiders are never far away. The dominant male cannot scare away several solitary monkeys so they usually are able to copulate with the females.

So why then do male monkeys fight?

Rowell offered several possibilities that need closer study. One of them is that fighting may serve as a form of communication among the males. Also, fighting appears to be sexually stimulating to the whole group, not just the combatants. This excitement, she said, may help bring on ovulation, helping to synchronize the births of babies.