Scientists study arms of dead men, suggest hands evolved so males could fistfight over females.
What's interesting is that I reported on that study in 2012-13.
It's good to see that I am ahead of the game :).
What is also interesting is that there are studies being conducted that are useful in explaining practice but they remain hidden in academic journals. My book will introduce readers to some of those studies and hopefully encourage others to access those types of studies and share them with those who are engaged in the practice of those techniques.