What will we lose when we are entirely homogenous

When the population of earth has intermixed that they are entirely a single population what will we lose? what will we gain? I think at least religion will be dead, but think of all the IQ points we'd lose as a population

>>2

The dream of fascists was to make all people uniform.

So you support a rich multicultural society where clearly heterogeneous people happily co-exist?
And here I was thinking you guys were a bunch of racist neo-reactionaries!