Some tropical butterfly species have unlocked an evolutionary way to live longer - CNN

- The tropical butterfly Heliconius hewitsoni lives for 348 days, nearly 25 times longer than close relatives.

- Scientists discovered these butterflies evolved anti-aging mechanisms beyond their pollen-based diet.

- Researchers said they hope studying these insects can reveal longevity insights applicable to human aging.

Since most butterflies live a short time, fluttering between colorful flowers for a few weeks before dying, a few rare exceptions have stumped scientists. Now, some long-lived tropical butterfly species are shedding light on the secrets of longevity.

Butterflies belonging to the Heliconius genus, which inhabit the tropical rainforests of South and Central America, have lifespans that vary wildly. The Dione juno butterfly lives for 14 days after reaching adulthood, while Heliconius hewitsoni lives for 348 days — nearly 25 times longer.

Other Heliconius species also have impressively lengthy lives, enduring between 106 to 277 days, according to a study on the phenomenon published Tuesday in the journal Nature Communications. Some scientists have speculated that Heliconius’ extended adulthood is due to the insects consuming an enhanced diet, rather than relying purely on carbohydrates like other butterflies.

But the exact reasons behind this unexpected longevity have been unclear, which is what inspired Dr. Jessica Foley, the study’s lead author and a postdoctoral scholar at Tufts University’s Jean Mayer USDA Human Nutrition Research Center on Aging in Boston, to take an in-depth look at the intriguing butterfly genus.

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“We see vast differences in lifespan across the animal kingdom — adult mayflies famously live only for a day, whereas some whales and sharks can live for hundreds of years,” Foley wrote in an email. “I’m interested in the evolutionary basis of these kinds of lifespan differences because they might hold insights relevant for healthy ageing in humans.”

Foley and her colleagues discovered that while nutrition has its part to play, some Heliconius have also evolved an anti-aging mechanism the researchers are still unraveling — and how it could be a model for understanding human longevity.

Studying the “extreme agers” of the animal kingdom is an uphill task for scientists, especially if they have to wait centuries for a species to reach what is considered old, Foley said.

Lesser-studied Heliconius butterflies presented the perfect case study since researchers could observe their entire life cycle in about a year. Only one other known butterfly, Myscelia cyanaris, lives longer than Heliconius, with a maximum lifespan of 380 days, but there is little data to suggest why.

Foley and her collaborators combined an expansive dataset to look at lifespan and aging patterns across the Heliconius genus, using information collected from commercial butterfly houses and mark, release and recapture studies, as well as controlled experiments.

The authors wanted to see whether removing an unusual food source from the diets of these butterflies would shorten their lifespan, she added.

Most adult butterflies feed exclusively on flower nectar, fueled only by carbohydrates rather than the amino acids and lipids — used for egg and sperm needed to reproduce — they received from plant material as caterpillars before metamorphosing.

“The general evolutionary strategy is to reproduce as much as they can until those resources are spent, which doesn’t take very long for these small insects,” Foley said of the lipids and amino acids. “They usually die soon after this finite resource is used up.”

However, most Heliconius species have adapted to feed on pollen — even as adults — which could provide the insects with more energy, the authors concluded. Pollen also contains lipids, which help with energy storage but also boost immunity.

The authors closely studied the relationship between Heliconius and pollen to see what health benefits the butterflies gained from their diets.

“I wanted to understand the real extent of this lifespan extension in Heliconius, to understand whether it was also accompanied by slowed physiological ageing, and to figure out whether they would still show a lifespan extension — indicating evolved mechanisms of longevity — even without the pollen,” Foley said.