The best theory out there is the 'Cold Winters' theory. But it leads to politically incorrect conclusions, so is not widespread.
Given that not only can we not explain our sociability, but that it's emergence seems nearly impossible according to our understanding of genetic natural selection, then opining on the dominant factors that drive modern intelligence, let alone drove our intelligence hundreds of thousands of years ago, is a hopeless endeavor.
Anyone providing answers to such higher-order questions could only be correct by accident. We have no way of assessing the validity!