Conventional wisdom in longevity studies used to be that the life span of a creature was roughly proportional to its body mass and heart rate—the big, slow elephant outlives the quick, small mouse. New research, however, presents a more complicated picture. Bats and birds, for instance, are small but tend to live longer than many larger creatures. Moreover, when scientists look within particular species, size does not correlate well with life span, although fast growth is often associated with reduced longevity. To some degree, resting metabolic rate does correlate, but for animals total energy expended over a lifetime may be the best indicator of all. Definitive answers in this field can be slow in coming, partly because the studies take a long time to do—a typical Galápagos tortoise, for instance, can outlast a scientist's career. And don't hold your breath for insights into the extreme life span of the bristlecone pine.
This article was originally published with the title "Which Creatures Live the Longest?" in Scientific American 307, 3, 96 (September 2012)
Fred Guterl is the executive editor of Scientific American and author of The Fate of the Species (Bloomsbury). Guterl is former deputy editor of Newsweek. His writing and editing have contributed to numerous awards and nominations from the American Society of Magazine Editors. His article "Riddles in the Sand," in Discover, was named best magazine article in 1998 by the American Association for the Advancement of Science, and his Newsweek article "The Wasteland," on Russia's plan to accept the world's nuclear waste, was honored by the Overseas Press Club for environmental writing. Follow Fred Guterl on Twitter
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