Splicing the killing gene

There is an opinion out there that those who partake in man vs man combat sportsmanship, are still very much in the phase of exercising the release of the ancient killing gene. For many observers out side of these sports activities whether it be boxing, kickboxing, MMA, or the likes, view these activities as a past shadow of man's barbaric nature that has yet to run out its coarse in terms of socially acceptable behavior.