American Scientist

Dim-wittedness is the one thing that unites nature’s most durable creatures, from sea turtles to jellyfish to paddlefish to nematodes. Short-lived prolific bugs tend to weather crises, as do some deepwater creatures, well insulated from events above, for instance, but there is little correlation between brain size and a species’ long-term survival.

Nature is loath to tamper with success, and it is loath to lay on brains where they are not needed. How and why brains develop in some animals and not in others is a mystery. The random mutations that increase brain size are probably ubiquitous, meaning that it is reasonable to expect that virtually every animal alive today has ancestors that produced brainier offspring which in turn had the chance to be fruitful and multiply. But the evidence is that with very few exceptions, evolutionary experiments to increase brain power have not taken. During the march of evolution, many animals have gotten smarter in the way we define it, but not much smarter. The likelihood is that nature has had more failures than successes when it comes to increasing brain size (and in evolutionary terms, the jury is still out on whether the human experiment will ultimately be a success or failure, but more about that later).

From The Octopus and the Orangutan: More True Tales of Animal Intrigue, Intelligence, and Ingenuity
Eugene Linden
Dutton, $23.95