A study has revealed a queer way as to how reptiles have an extended life span: they go vegetarian and postpone mating for later in life. The cold-blooded animals displayed intricate links among longevity, environmental conditions and life-history characteristics.
The authors of the study have suggested that the same might be true fot birds and mammals as well, but no evidence exists for such a claim.
The researchers analysed the lifespans of more than 1000 lepidosaurs. The latter form part of the subclass Lepidosauria which groups together reptiles possessing certain characteristic features, like keratinised, overlapping scales. They surveyed around 672 lizards and 336 snakes, gathering data about their body size, age at first reproduction, body temperature, and dietary habits.
Delay reproduction and live longer!
The results showed a correlation between “slow” life-history traits and long lifespan. The slow life-history features included delayed reproduction, less offspring, and colder body temperature. This also implied that those who began mating at a younger age and thus producing more offspring, lived for a shorter period of time.
More pregnancies might mean shorter lives
Reproduction comes with certain costs. The more one invests in the activity, the more energy does one have to put in, which might lead to the suppression of the immune system. This might be impacting on the longevity of the individuals.
One of the authors of the study, Dr Danirl Pinchiera-Donoso, stated that: “We observed that more sex (or at least more pregnancies) means shorter life, very much like the rock star adage ‘live fast, die young.’”
Do vegetarian reptiles really have an upper hand over carnivorous ones?
When it comes to diet, the herbivores of the group lived longer than the carnivorous ones. This might be because the meat the latter consume are rich in proteins which contribute to their fast growth which, in turn, causes them to reproduce more, while herbivores reach sexual maturity later in life, and reproduce less.
However, the results might also be interpreted in a completely different way: carnivores feed on other animals which they have to hunt for. Being on the look-out for preys and ultimately catching them entail risks of hurt and death. Also, the consumption of meat comes with a greater risk of being infected by parasites. These factors would mean that the shorter lives of the carnivores are more of an indirect consequence because of their eating habits and lifestyles.
The colder the environment, the longer the life-span
The study results also showed an association between body size as well as habitat and longevity. For instance, larger species which live at high-altitude habitats in cold areas appeared to live longer. Colder temperatures might imply that the animals hibernate often enough, thereby conserving energy, and using up less energy since they have fewer activities. Warm temperatures, on the other hand, will contribute to higher metabolic rates and hence faster growth, where the individuals use more energy, thereby depleting their ‘life stock’.