We already know that when it comes to brains, it’s not the size that counts. Having a big brain isn’t necessarily a sign of intelligence. The study by Eric Abelson, a researcher in Stanford’s biology department, believes that having a large brain might actually be a handicap. Animal species with the largest brains (in relationship to their bodies) may be at greater risk for extinction. How did he come to this conclusion?

Using data collected from 88 studies, Jacob Pietschnig and his team created an overview (which appeared in Neuroscience and Biobehavorial Reviews in October 2015) examining the relationship between brain size and intelligence, and were able to conclude that human intelligence has less to do with brain size than brain structure. Thus, while men generally have larger brains than women, they do not have more advanced cognitive skills. Similarly, in the animal world, the sperm whale, with its 20 pound brain, is not considered to be highly intelligent.

In his study published in Proceedings of the Royal Society B, Eric Abelson points out that, in the animal world, having a large brain could have a negative impact on survival. In his research, Abelson calculated the brain size of 1679 animals (160 different species) and compared this data to data provided by IUCN (International Union for Conservation of Nature). One of the organization’s activities includes measuring the risk of extinction for thousands of species and sub-species. For the sake of comparison, Abelson chose to use encephalization coefficients as the basis for the calculation. The coefficient indicates the size of the brain in comparison to the body.

The results demonstrate a correlation between encephalization coefficient and the species’ probability of extinction; the relationship is strongest among small animals. According to Abelson, maintaining a large brain comes at a metabolic cost. It requires greater energy consumption without necessarily providing a fitness advantage. This research thus represents a valuable asset in estimating the vulnerability of a species.

Finally, Eric Abelson raises this “ecological” warning in his study: that an increase in knowledge cannot protect fauna from the dangers of the modern environment.