Reptiles' Secret to a Long Life: Avoid Meat and Sex

Researchers find that veggie-eating lizards that live in cold climates and reproduce infrequently live longer.

Meet the world's oldest known Gila monster. (Photo: Courtesy Tel Aviv University)

Oct 29, 2014· 1 MIN READ
Katharine Gammon has written for Nature, Wired, Discover, and Popular Science. A new mom, she lives in Santa Monica.

Why do some animals live to a ripe old age—a Gila monster at the Tel Aviv Zoo, for instance, is well over 40—while their compatriots die young?

For snakes and lizards, at least, the answer seems to be to eat more veggies and have less sex, according to a new study published in the journal Global Ecology and Biogeography.

An international group of researchers collected data on 1,014 reptile species and analyzed factors affecting their life spans. The scientists also looked at distribution maps for each species and assessed the temperature, rainfall, and general productivity of each area where the lizards lived.

They found that long-living lizards are generally characterized by delayed and infrequent reproduction, a small number of offspring, larger hatchlings, and colder body temperatures.

The environment had a strong impact on longevity, the study showed: Lizards that occupy higher latitudes live longer. “While our human metabolism speeds up in cold climates, lizard metabolism slows down,” said Shai Meiri, a biologist at Tel Aviv University and a coauthor of the study. “The other thing is that in colder regions, the animals hibernate, so there’s no one around to eat them.”

Faster metabolism also means that all body processes speed up, from accumulation of harmful mutations to increased oxidative stress. That means the animals age faster.

The team discovered that herbivores live about 20 percent longer than similar-sized meat eaters. Meiri pointed out that a diet rich in meat may lead to faster growth, earlier and more intense reproduction, and hence a shorter life. “Trying to hunt prey is dangerous, which is another possible connection,” he said.

Further research will examine the longevity and life habits of turtles. The scientists also hope to test their findings on a set of lizard species with different diets and to determine the consequences for growth and time to maturity.

But human vegetarians shouldn’t get too excited.

“The idea that vegetarians live longer is provocative, but lizards have very different bodies than humans,” Meiri said.