Is it better to have a small or a big brain?

We already knew that having a big brain was not necessarily a guarantee of intelligence (read our article), but, according to a recent study, it even rhymes with danger of extinction. For small mammals, at least.

Over the past 40 million years, mammals with larger relative brain size were indeed less likely to become extinct, as their brain size gave them a cognitive, and therefore evolutionary, advantage. But in mammalian species living today, we see the opposite trend. A new study suggests that mammals with large brains are at greater risk of extinction.

In this study published in Proceedings of the Royal Society B, Eric Abelson calculated the brain size of 1,679 animals (from 160 different species) and compared these measurements to data from the International Union for Conservation of Nature, which assesses the risk of extinction for thousands of species and sub-species. species. By comparing these data, the scientist highlighted a correlation between the encephalization coefficient and the probability of extinction. A trend that would mainly concern small mammals.

Maintaining a large brain would indeed have a significant metabolic cost involving higher energy consumption (animals must eat more to feed it) without providing a better adaptive value. And for Eric Abelson, the costs of a high coefficient of encephalization exceed the advantages for small species, which cannot protect themselves from modern environmental dangers.

This discovery comes at a time when wildlife seems to be experiencing a sixth mass extinction crisis, linked to human activities. By establishing this brain/survival correlation, the researcher tends to define which species are in danger of extinction and which are the ones that would benefit the most from conservation measures.

Sources: Proceedings of the Royal Society, futura-sciences

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