A long-simmering debate in sports is whether home-court advantage - an increase in performance when competing in familiar surroundings - actually exists. An experiment involving lots of mouse fighting says it absolutely does. It's all down to brain chemistry.
It's one of those experimental designs that sounds more than a little ridiculous, at least until you realize this could actually lead to some good science. A team of zoologists at the University of Wisconsin wanted to study what effect winning a fight both "at home" and "away" had on mice. To accomplish this, they paired off mice to fight in both their own cages and the unfamiliar cages of their competitors. In other words, they basically founded the world's first mouse fighting league.
One challenge they faced was ensuring the right mice won the right fights. They got around this by borrowing a trick from seedy boxing promoters the world over, pairing the favored mouse with a weaker, less sexually experienced opponent who could not hope to spring an upset. Once a mouse had notched three consecutive victories, they studied its brains for any chemical changes.
They discovered that the victories for mice that had fought both home and away caused a spike in the hormone androgen, which is linked to the area of the brain that causes social aggression. This means, naturally enough, that those mice that had already won matches wanted to keep fighting. Even more intriguingly, those mice that had won all three fights at home showed increased sensitivity to androgen in areas of the brain that govern motivation and reward, almost as though the mouse was responding chemically to the successful defense of its home turf. The home-winning mice were also more likely to win their subsequent fights than their away-fighting counterparts.