In mammals, the increasing importance of information processing helps explain the evolution and growth of the cortex, the gray, outer layers of the brain. The cortex provides lots of space for calculations and a lot more calculating ability, so it allowed better problem-solving in unfamiliar situations or when other decision-making systems were deadlocked. Eventually, the brainiest mammals would evolve general information-processing and problem-solving systems that were to those of the bacterial world what the Internet is to an abacus.
