Testosterone doesn't directly cause aggression, it causes people to compete which may manifest as aggression if aggression leads to status in whatever culture you live in. - my recollection of Robert Sapolsky

nothing to do with testosterone but emotional intelligence

All I know is that we're rapidly changing things that have been much more stable for thousands and thousands of years. Getting rid of aggressivity is good but if it takes your fertility/strength/bone density/dementia resistance/&c. with it... but then again is humanity a good thing ?