A simpler family tree?

Apart from a general outline, human evolution is far from settled science.  Any day a new finding can change our interpretation of what we know.  The Dmanisi finds are an example of that.  Any "grand narrative" has to acknowledge the uncertainty.   We tend to claim a lot more certainty to our knowledge than is justified.

The interpretation of the Dmanisi finds has kicked up a scientific controversy and whichever way it is resolved (or proves to be unresolvable), we will know a little more, and also know the limits to our knowledge a little better. 

The five Dmanisi skulls

The five skulls found in one place at one geological time (they are from about 1.8 million years ago) might have been classified as different species had they been found separately.  The principle of parsimony requires us to postulate they are the same species.  The range of variation is similar to the range of variation found in modern chimpanzees and humans.   This opens the question of whether the finds around the globe are at best regional variations of one species?