ESKIMO hunters killed a bowhead whale off the coast of Alaska last month and began to chainsaw their way into its blubber. They stopped when the saw hit the tip of an old harpoon lodged deep inside the whale. Historians identified it last week as part of a bomb lance, a harpoon manufactured for only a few years in the late 1800s in New Bedford, Mass. Whalers probably fired it at the bowhead around 1890, when the whale was probably a teenager, and it carried the harpoon for the next 115 years before finally being killed by a modern one.

Whales don’t carry birth certificates, so scientists usually can make only rough estimates of their age by examining protein in the lenses of their billiard-ball-size eyes. The bomb lance is pretty clear proof that this particular bowhead whale lived longer than any human on record. Had the whale escaped the second harpoon, scientists say it might have lived another 80 years. Indeed, the age of another bowhead examined by scientists in 1999 was put at 211 years. It holds the record for the longest-lived vertebrate.

But bowheads certainly have competition. Rockeye rockfish can live to be at least 205 years. A Galápagos tortoise named Harriet is reputed to have lived 175 years. At the other end of the spectrum, some animals live eye-blinkingly short lives. The pygmy goby fish in Australia, for instance, lives for only eight weeks. Male Acarophenax tribolii mites live only a few hours within their mothers, just long enough to fertilize their unborn sisters.

Why do bowheads hang on so long, and mites for such a short time? The answer lies in the evolution of aging. Animals can evolve either to produce a lot of babies very quickly, or to live longer but reproduce more slowly. Animals facing lots of risks — such as getting eaten by predators — may be better on the fast track. Scientists who have studied the life spans of flies in the laboratory have found that if they kill off lots of flies, the remaining ones evolve to mature faster and reproduce more. But this accelerated life comes at a cost: it damages their cells and they age quickly.