Lizards' Secret of Longevity: No Meat, Little Sex

Researchers identify factors that extend reptiles' lifespan – but can't say it works for humans, too.

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A tuatara, endemic to New Zealand.
A tuatara, endemic to New Zealand. Credit: Dreamstime

Here’s a tip for a long life: Abstain from meat, don’t have sex frequently and in general, take life at a slow pace. It works for reptiles, at least. A newly published study reveals that vegetarian reptiles that delay reproduction and engage in less sexual activity live about 40 percent longer than reptiles who feed mainly on meat.

The study, published in the journal Global Ecology and Biogeography, was conducted by an international team of researchers headed by Prof. Shai Meiri, Dr. Inon Scharf and doctoral student Anat Feldman of Tel Aviv University’s Zoology department. The team examined how environmental factors such as climate, food hunting and reproduction influence snakes and lizards’ life expectancy. The group also consisted of scientists from Britain, the United States, Ecuador and Malaysia.

The study is based on researching 1,014 species of scaled reptiles, including hundreds of species of lizards and snakes. It concludes that frequent sexual activity and early sexual maturation are associated with shorter lives. On the other hand, scaled reptiles that live longer are characterized by a vegetarian diet, delayed and infrequent reproduction and colder body temperatures.

The researchers gathered data about the reptiles’ body size, earliest reproduction age, reproductive mode (laying or giving birth), clutch or litter size and brood frequency, diet and activity time (daily or nocturnal).

The tuatara (Sphenodon punctatus), a reptile endemic to New Zealand, weighs up to 1 kilogram and “lives to a ripe old age of 91, as far as we could ascertain, but probably could live to 100 or more years,” Meiri told Haaretz.

“It feeds mainly on plants and its secret for a long life is simply doing everything slowly. It has no predators and when you have no predators you can afford to walk slowly and reproduce slowly. It reproduces once in four years. Reproduction takes a great toll on the female’s energy so she has a long time to get herself in good shape again. It also helps that she’s not competing with others of her species, she lives in a cold place and her body temperature is 18 degrees. That means her metabolism is extremely slow.”

In contrast, Labord’s chameleon, which is endemic to Madagascar, “lives eight months at the most and spends more time as a fetus than as a mature animal,” says Meiri.

It weighs 60 grams at most and feeds mainly on insects and arthropoda. In general, it lays numerous eggs, and the more it lays the shorter its life span, he explains.

The researchers assume that a low-calorie vegetarian diet leads to slower reproduction and a longer life span. Also, finding vegetarian food involves fewer risks than hunting. Reptiles that live longer usually have a slower “life pace” including delayed reproduction, laying eggs a few times a year and laying smaller eggs or giving birth to fewer offspring at a time. The study also found that large reptiles living in cold climates live longer.

“What interests us is the evolution of their life history,” says Meiri. “The synchronism of their life events affects reproduction and their longevity. This is reflected in their diet as well. We found that herbivores live 20 percent more than omnivores and 40 percent more than carnivores.”

The vegetarian diet is not the only explanation for reptiles’ life expectancy. Their survival is also based on environmental factors such as predators, temperature and others.

“The characteristic that has the most profound effect on their life span is their physical size,” he says.

Meiri cautions not to jump to conclusions from the study regarding humans. “We’re dealing with completely different creatures and there’s no basis for comparison. At most it’s an idea for future research,” he says.

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