There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
"Our results show that brain size explains variation in population density among species, with big-brained mammals occurring at lower population densities. We found no evidence that “being smart” compensates for the increased costs of a big brain, although it likely does in some groups, like humans. We, humans have used our big brains to maximize exploitation of resources and overcome the finite energy limitation of an area by manipulating the limits and widely importing resources across sites. On the other hand, for our closest relatives, primates, big brains are costly and linked to lower population densities.
We also found specialized diets are directly linked to lower population densities and generally, there was an effect of total body size, as expected larger mammals live at lower densities. However, direct links between body size and population density were not always supported, suggesting brain size could be a better, more direct predictor of energy requirements, at least in some groups. An alternative explanation could be that brain size is just a more accurate descriptor of size: brain size varies less across and within adults of one species than body size, but the sensitivity analyses we completed suggest this is not likely the case.
If big-brained mammals are generally found at lower population densities and lower local abundance increases local extinction risk, this could be bad news. Indeed, we found in another study that big-brained mammals have increased risk of extinction (Gonzalez-Voyer et al., (2016). Big brains have provided evolutionary advantages and may still be useful in modified anthropogenic landscapes (Santini et al., 2019), but they come with costs that ultimately may be too high. Paraphrasing Darwin, this could be survival of the thickest."
That could help to explain why polar bears are intelligent enough to hurl rocks at others (whether humans or walruses, if you see my post on the thread for polar bears)!
Bear Intelligence
