Dangerous Times: Guppies don't follow rules for old age

A new study of wild guppies could unsettle a decades-old idea about the role of danger in the evolution of aging.

Biologists in the 1950s predicted that in a treacherous habitat, creatures would evolve so that they'd age rapidly, explains David N. Reznick of the University of California, Riverside. However, when he and his colleagues compared guppies from streams with many predators with streams posing few threats, the prediction failed. In the absence of predators, the guppy lineages from the menacing steams didn't tend to die early, he and his colleagues report in the Oct. 28 Nature. "The classical theory is incomplete," says Reznick.

"It's the first test with species that evolved under natural conditions," says senescence researcher Marc