Like teenage boys hanging out on a street corner or fans cheering at a football game, animals behave differently when they're in a large group than they do when they're by themselves.
The mechanics and patterns of nature's aggregations - schooling fish, flocking birds or swarming insects - provide valuable understanding for how such groups behave in, and survive, trying conditions, says a University of Washington zoologist.
What looks like a complex dance - an entire group suddenly changing directions or exploding and reforming - is actually a series of interactions between members of the group reacting to outside influences, says UW research assistant zoology professor Julia Parrish.
"There's a beautiful, aesthetic, very artistic side of it, but there's also a very mathematical and a very evolutionary aspect of animal aggregation," says Parrish, who writes about the complexity and patterns of animal aggregations in the April 2 issue of the journal Science. The paper, co-authored by Leah Edelstein-Keshet, an associate mathematics professor at the University of British Columbia, is part of a package of Science articles that explore the uses of complexity theory in natural and social science.
Pattern that emerges from aggregation is not limited to living systems, Parrish says. Snowflakes are a classic example. A single flake falls and is beautiful to look at. A stormful of flakes stick together and are carved by the wind into elaborate ridges and cornices. A winter's worth of flakes slip and slide and adjust to gravity, eventually producing an avalanche.
But animal aggregations have an evolutionary side.
How individuals react to outside influences can determine their own survival, as
well as the survival of other group members. A herring that turns right when the
school turns left faces certain death, Parrish says. But a herring that always
cooperates with the group and never competes might die of starvation. Finding
the threshold between
Contact: Vince Stricherz
University of Washington