Google "Boskops" and you will find a lot of speculation and debates about this group of hominids. I'm going to post below some interesting links where you can find full debates.
The below skull was found in the autumn of 1913 by two farmers digging a drainage ditch in a small town called Boskop, about 200 miles inland from the east coast of South Africa.
These farmers took the skull to the director of the Port Elizabeth Museum, in a small town at the tip of South Africa and the it came to the attention of S. H. Haughton, one of the country’s few formally trained paleontologists.
The Boskop man's skull was originally claimed to be 30 percent larger than that of modern humans therefore more intelligent. Another strange feature was that these people had small, childlike faces. Anyone having a deja-vu around alien abduction movies?
More info here:
http://discovermagazine.com/2009/the-brain-2/28-what-happened-to-hominids-who-were-smarter-than-us