We are not talking about a different species. Yes there is more to it than size, but size helps. These were also people that had a normal sized body but an enlarged brain - so that increased brain would not have to control more mass. I said as much in the article, if the increased size correlates to only a 10-20% it would indicate that they could have had an IQ of 149. This is not my data, but from the book Big Brain: The Origins and Future of Human Intelligence written by two highly respected neuroscientists - one teaches at UC-Irvine and the other at Dartmouth.

They broke from the mainstream group-think to put forth their theories on the Boskop people, and I applaud them for it.

Finally, what is evolution but a series of mutations, or what you call defects in your comment.