Even if you could find modern human brains that small, they would be incredibly rare. (pandasthumb.org)
So although the extreme lower range of modern human brain sizes does overlap that of Homo erectus, their skulls are very different: in H. erectus, the brain case really is smaller in relation to the rest of the skull. (talkorigins.org)
Because of the obvious humanness of the Turkana Boy fossil, and the fact that H. erectus brain sizes overlap the extreme lower range of modern human brain sizes, creationists have nowadays almost entirely abandoned the old line (popularized by Duane Gish) that Peking Man and Java Man are apes, and now generally claim that Homo erectus fossils are a variant form of modern humans (ignoring the inconvenient fact that there are many obvious differences between Homo erectus and Homo sapiens). (talkorigins.org)