PIEN HUANG, HOST:
What we eat has the power to extend the length and quality of our lives. Decades of research backs this statement for humans. Now the same claims can be made about some butterflies. While many species live only a few weeks total, Heliconius butterflies can live for months, up to 25 times as long as other related butterflies. New research shows that their diet plays a huge role.
Jessica Foley is a postdoc researcher at Tufts University, formerly with the University of Bristol, and she joins me now to explain. Welcome to ALL THINGS CONSIDERED.
JESSICA FOLEY: Thank you so much for having me.
HUANG: So tell us about this butterfly. Why is it living so long?
FOLEY: That's exactly the question I had when I started this six years ago now. So a lot of people have known - at least within the Heliconius community and also in the sort of broader insect longevity community - that these butterflies could live for up to six months, some people said. And most people had kind of put it down to the pollen because pollen contains lipids. It contains amino acids, which are the building blocks of protein. Whereas most butterflies, including Heliconius' close relatives, just feed on nectar, which is basically just sugar water. It's pretty much just pure carbs.
So it's kind of this intuitive explanation, right? They're eating something that's more nutritious that helps them to live for longer. And so we did some further experiments and basically found that even without the pollen, they're still living for longer. So they've evolved some kind of other pro-longevity mechanisms that are helping them to live for longer, even without this nutritional advantage.
HUANG: And when you say that they're able to lay eggs for most of their lives, you're basically saying that they can stay vigorous until the very end of their lives, is that right?
FOLEY: Pretty much, yeah. I mean, so we looked at a couple of things. So butterflies with the pollen are able to lay eggs up until the end of their lives. But we also wanted to know about other metrics of aging, you know? A lot of insects show some kind of a muscular decline with age. Humans also show this. So we came up with a kind of butterfly strength test. And we found that in Heliconius' shorter-lived close relatives, they do seem to show a decline in grip strength with age. So on average, at the end of their lives, they're pulling 25% less than they were at the beginning. But we didn't find that in Heliconius. They don't seem to show any sign of weakening with age.
HUANG: Yeah. Can I ask you what a grip strength test for a butterfly looks like? What is that?
FOLEY: Yeah, absolutely. So yeah, good question. You know, how can you tell how much a butterfly can bench? We basically just put a small wooden perch onto a, like, wooden base and then put the entire contraption on a lab balance. And you hold a butterfly by the wings and gently lower it until its legs grasp the perch. They kind of do that naturally. It looks - I mean, it seems like - a little bit like a branch to them. And then once the butterfly's holding on, you gently tug it off. And as the butterfly tugs, the reading on the balance will drop negative. And eventually, it'll let go. A butterfly's, as yet, incapable of lifting the whole weight of the contraption. We called it the pull-inator (ph), by the way. That was kind of...
HUANG: (Laughter) Clever. So I know that you are really into butterflies, and I am very into insects, as well. But why would this be an important discovery for someone else that might not be so into insects?
FOLEY: Even with organisms as distantly related to humans as butterflies, a lot of the mechanisms of aging at the molecular level are pretty highly conserved. So if you think about it, you know, all organisms have DNA. And one of the, like, potential explanations for why we age is that as we age, you know, we accumulate DNA damage. And so some of the really interesting stuff coming out of the comparative biology of aging shows evidence for improved DNA repair mechanisms in long-lived species, so things like the naked mole rat or the bowhead whale.
And again, we haven't yet identified what these prolongevity mechanisms are in Heliconius, and they might be something completely irrelevant for us. But they might tell us something interesting about the process of aging more generally that could be helpful for learning about healthy aging in our society.
HUANG: We've been speaking with Jessica Foley from Tufts University, formerly with the University of Bristol. Jessica, thank you.
FOLEY: Great. Thank you so much for having me. Transcript provided by NPR, Copyright NPR.
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