Why else have humans evolved such giant brains that it puts both mother and baby at serious risk and consumes huge amounts of energy? There's also correlations

Why else have humans evolved such giant brains that it puts both mother and baby at serious risk and consumes huge amounts of energy? There's also correlations between brain size and various intelligence metrics, which, while certainly not definitive, is still strong evidence. Of course it's not just a simple matter of size, particularly across species (e.g. a blue whale isn't smarter than a human). But it helps/enables.