In millions of years

[Witty]

But they say evolutionary changes happen from necessity, to adapt.

We are already living in a world we have made for ourselves, we are comfortable and have no need to adapt.

I dunno if that would apply to the brain's evolution, but I don't think just because we have evolved at a certain rate in the past means we are still evolving at that rate, if we have less need to change then we will evolve slower.