The Butterflies That Defy Aging

For most butterfly species, an adult’s life is brief and—with all due respect to butterflies—unextraordinary. After emerging from its chrysalis, a butterfly will stretch its new wings and set off in search of nectar and sex, spending the rest of its days flitting among flowers, mates, and spots to lay eggs. Within a few weeks, it’ll be dead.Not so for Heliconius butterflies. Adults in this genus can survive for many months after metamorphosizing, which ranks them among the longest-lived butterflies ever documented. In one case, scientists observed a Heliconius species in a butterfly house living close to a year—25 times longer than relatives in a similar genus. From the human perspective, that’s the rough equivalent of another great-ape species surviving for more than a millennium. Through their final moments, too, these butterflies maintain an unusual vivacity. In experiments, aged Heliconius feed, flap, and lay eggs just as vigorously as their younger peers; even their muscle strength doesn’t measurably deteriorate, according to a new paper, published today in Nature Communications, from Jessica Foley, a researcher at Tufts University studying aging, and her colleagues. Foley has seen Heliconius butterflies zooming around their cage all day, only to find them dead come nightfall. “I not sure how they’re declining,” or really if they are at all, she told me. The butterflies seem to defy the typical process of aging.Other long-lived animals have evolved strategies to minimize or counteract life’s wear and tear. Naked mole rats and bowhead whales are particularly good at repairing damage to their DNA; elephants have extra cancer-suppressing genes; bats limit the buildup of cellular waste in their body both by tamping down potentially damaging immune responses and by slowing their metabolism to a near-halt during hibernation. Researchers are still working out Heliconius butterflies’ secret, but they do know that the insects have a very unusual diet: As adults, they su