At the risk of coming off like a know it all jerk, Baird is correct. Darwin used the term "natural selection" meaning survival of the ones most adapted to their environment - not necessarily the biggest or most powerful of the species. Sociologist, Herbert Spencer, and others who believed in things like eugenics and later would be termed Social Darwinists, are the ones who believed that the most powerful and ruthless in society would and should prevail. He's actually the one who coined the term "survival of the fittest."

But, I wholeheartedly agree with everything else that you've said - particularly that we survived when other hominins did not because we were the friendliest. Going to check out the book you linked now.