Humans live towards the end of the intelligence spectrum and at the borderline where adding more intelligence would risk wiping out the entire species.

The way to make humans stop fighting and not draw circles and divide themselves into in and out-groups is to make them more intelligent and see beyond minor shape and color differences.

But then they will also become so brilliant that they will not be dazzled by physical differences in the opposite sex that all animals have a physical and emotional reaction towards each other.

You are effectively risking wiping out the civilization.

We are already at the far edge of the goldilocks zone!