Do fish hold the secret to why some people are more social?

SEATTLE - It may seem like fish and humans have very little in common, but researchers at the Fred Hutchinson Cancer Research Center are studying fish behavior to eventually learn why some people are more social than others.

Dr. Anna Greenwood, a research fellow at the Hutch focusing on animal behavior, discovered two parts of the fish genome that determine whether they swim in schools - their desire to school and how well they do it. That's important, she said, because if researchers can identify the genes that influence fish's interest in being social they may be closer to understanding how genetics drive human social behavior.

"The motivation to be social is common among fish and humans," Greenwood said. "Some of the same brain regions and neurological chemicals that control human social behavior are probably involved in fish social behavior as well."

Greenwood studied two groups of threespine stickleback fish - one from the Pacific Ocean in Japan and one from a lake in British Columbia. Though both groups were raised in identical lab conditions, they behaved differently from each other when placed together in a schooling situation.

"That really suggests that there's some kind of genetic factor controlling this difference," Greenwood said.

Dr. Hans Hofmann, a professor of integrative biology at the University of Texas at Austin, said the study contests the assertion that human behavior is too complex to understand.

"I think it shows that even such complex behaviors associated with other individuals in a very rigid and organized manner can be dissected genetically," he said. "Studies like this tell us that we might get there eventually."

Greenwood said this research has set the stage for determining exactly which genes control social behavior in both fish and humans.

"All vertebrates, including fish and humans, share the same neurological chemicals and hormones that influence behavior," she said. "How much the fish want to be social does share a common mechanism with human social behavior."

If researchers can determine which chemicals and hormones influence behavior, Greenwood said those factors can be manipulated in a therapeutic sense, just as antidepressant medications influence serotonin levels.

To conduct her research, Greenwood had to influence the lab fish to school. Researchers suspended a bicycle wheel above a circular tank with a motor that could turn the wheel. They then suspended eight hand-made model fish from the bike wheel with wire. The fake fish appeared to swim in a school, enticing the live fish to follow.

But, what do schooling fish have to do with cancer research? Greenwood said our genetic differences do not only influence behavior but can also affect our susceptibility to illness and disease.

"We don't know where the next important scientific discovery to benefit human health will come from," Greenwood said. "We have to study more general health topics."