Small, Big-Brained Animals Dodge Extinction

ananyo writes "Large-brained animals may be less likely to go extinct in a changing world, perhaps because they can use their greater intelligence to adapt their behavior to new conditions, according to an analysis presented to a meeting of conservation biologists this week. Plotting brain size against body size creates a tidy curve. But some species have bigger or smaller brains than the curve would predict for their body size. And a bigger brain-to-body-size ratio usually means a smarter animal. The researchers looked at the sizes of such deviations from the curve and their relationships to the fates of two groups of mammalian species — 'palaeo' and 'modern'. Analysis of each group produced similar results: species that weighed less than 10 kilograms and had big brains for their body size were less likely to have gone extinct or be placed on the International Union for Conservation of Nature red list for endangered species. For species larger than about 10 kilograms, the advantage of having a large brain seems to be swamped by the disadvantage of being big — such as attracting the unwelcome attention of humans."

Comments

Re:Except

[Anonymous Coward]

Actualy the important bit is that brain burns a lot of energy which is why we don't see smart animals everywhere. Given similar body weight, having more of that weight occupied by brain means that the animal has evolved with greater importance of inteligence (larger brain needs more energy) but just because inteligence is more imporant compared to other similaranimals doesn't mean there's more of it than a larger animal would have. Anyway, the point stands - inteligence helps to survive, at least as long as you don't become too big to evaid the best killing machine on Earth - fully armed and trained hordes of Homo Sapiens Sapiens.

Neanderthals

[tobiah]

Neanderthals and a number of other extinct early hominids had brain sizes of 1600cc to 2200cc. Modern homo homo sapiens have a brain size of around 1200cc to 1500cc. Einstein's brain was around 1250cc. Sharks are the most enduring vertebrate on Earth, and have one of the lowest brain/body mass ratios. There's plenty of evidence to refute the premise.
Marris in her Nature article is implying that large brain/body ratios increase species survival likelyhood, based on comparing a "primitive" class of mammals to a "modern" one. But it could just as well be their digestive system was more adaptable, superior immune systems, etc. She started with a theoretical classification of living and extinct mammals (paleo and modern) and tried to support her theory that one has a survival advantage. This is trying to make the empirical data fit the theoretical model, and is crummy science. If one were actually interested in extinction, they should study different species and why they went extinct or not, and then build a theory based on those empirical results.