There is evidence to indicate that problem solving ability may be related to brain size in normal humans, however. Given that men tend to be bigger than women, this is not surprising. However, there seems to be a sex difference in brain weight that does not disappear when body surface area and height is controlled for. Solving a problem means mastering a new situation. It seems, then, that both expertise and problem-solving ability may have played a role in increasing the brain size of humans.
Expertise has a limited area of applicability.
Leading a hunter-gatherer life in a way that increases one's probability of surviving and spreading one's genes may often call for being a jack of all trades, not just a master of one. General principles and heuristics, as well as trivia. This brief commentary does not purport to show that the large brain of modern humans has been selected to help us solve problems and remember facts. Nor does it demonstrate that a bigger brain will give individuals an increased problem-solving ability, a greater interest in factual knowledge, or better semantic memory. Furthermore, some of the arguments are based on findings indicating a sex-related difference in the brain size of humans, even after controlling for height and body surface.