There is actually a lot of legitimate research on brain size, and here is the latest:
So what did they find? Bigger brains correlate with greater self-control:Self-control is quite different from IQ, but turns out also to be a huge predictor of success in life. It recently got a lot of publicity as part of the Tiger Mom Chinese-Jewish Triple Package.
Our phylogenetic comparison of three dozen species supports the hypothesis that the major proximate mechanism underlying the evolution of self-control is increases in absolute brain volume. ...
Can we draw any conclusions about human evolution from this study? It's hard to generalize -- just as we cannot conclude much about cognitive evolution from comparing whales and elephants only to humans, we can't predict much about humans by looking only at the broadest phylogenetic pattern. Yet, the importance of foraging and diet breadth to the evolution of primate cognition is provocative. The study seems to weigh in favor of tool use and foraging as primary drivers of human brain evolution, instead of social dynamics.
But that contrast is surely misleading. Human tool use and foraging depend on social cooperation and social learning.
Gould did not admit his mistakes, even when confronted. I sometimes post things that I have changed my mind about, but Gwern's mistakes has me beat. He has detailed descriptions of his changes.