[nonameiguess]

Probably not by natural pressures, though. We're more than intelligent enough to outcompete any species that might try to fill the same ecological niche as humanity. No benefit to even more brain power. It would more likely take intentional selective breeding if we wanted to go that route.

[dmurray]

Most evolutionary progress comes from outcompeting inferior members of your own species, not others. But it's also true that in modern society, intelligence doesn't seem to confer reproductive fitness.