You may see a headline or ten today screaming, DOGS SMARTER THAN CATS! (Subhead: Scientists Say So!) It may not surprise you to learn that those headlines are a little overblown. But what the scientists actually say is pretty interesting, too.
Susanne Shultz and Robin Dunbar at Oxford University studied "encephalization," which is how much a species increases its brain size over evolutionary time. If your ancient ancestors had pea brains, but nowadays you have a giant brain (compared to your body size), congratulations! Your species encephalized. Since it costs a lot of energy to power a big brain, scientists assume that highly encephalized species are getting a big benefit out of those brains in the long term (say, by inventing tools).
Shultz and Dunbar conducted a statistical analysis that included 511 mammal species. Within groups of related species, they included fossil data from extinct species as well as data ...
