
Well no, perhaps human intelligence was not caused by a virus as such but according to new research, its evolution may well have been made possible by an ancient retrovirus which infected an early vertebrate ancestor.
In a blog just a couple of days ago, I explained the origin of the endogenous retroviruses (EVRs) which now form 5%-10% of the human genome, much of it believed to be junk. I also explained that some of it might well have been exapted for other purposes, just as you might expect of a lot of 'spare' DNA hanging around for tens, maybe hundreds, of millions of years.