Less Sex and More Vegetables May Lead to a Longer Life

When it comes to lizards, the secret to a longer life may be less sex and more greens. Scientists have discovered that reduced reproductive rates and a plant-rich diet increased the lifespan of reptiles.

In order to better understand lifespan among reptiles, the scientists collected literature on 1,014 different species of reptiles, including 672 lizards and 336 snakes. They examined their body size, earliest age at first reproduction, body temperature, reproductive modes, litter or clutch size and frequency, geographic distribution and diet.

"There were aspects of this study that we were able to anticipate," said Shai Meiri, the lead researcher, in a news release. "Reproduction, for example, comes at the price of great stress to the mother. She experiences physiological stress, is unable to forage efficiently, and is more vulnerable to her surroundings. This reflects evolutionary logic. To relate this to humans, imagine the physical stress the body of an Olympic gymnast experiences-and the first things that disappears is her period. In reptiles, it also increases the probability of being preyed upon."

That's not all researchers found. They also discovered that lizards with a plant-rich diet lived longer than similarly-sized carnivores that ate mostly insects. It seemed that a protein-rich diet lead to faster growth, earlier and more intense reproduction and a shortened lifespan. In contrast, herbivorous reptiles that consumed nutritionally poorer food reached maturity later and lived longer. That said, it could also be that hunting may be riskier than munching on plants.

"If you're an animal, hunting your food can be dangerous," said Mieri. "You risk injury or even death. This is why you cannot simply transfer this logic to humans. Going to buy a head of lettuce at the supermarket is just as risky as going to the meat department. As a reptile, if you eat plants, you may need to be frugal, take life more slowly, and save your calories for digestion. You are forced to have a slower life, a more phlegmatic existence."

The findings reveal a bit more about how reptiles adapt to their lifestyle and how reptiles have evolved over time.

The findings are published in the journal Global Ecology and Biogeography.