Shedding Light on Early Homo

This week, the news of new fossil finds northern Kenya hit the anthropological scene.  You can find a good summary by Kate Wong here, and at Hominid Hunting here.  For further, bloggy, but knowledgeable commentary, check out Adam Van Ardsdale's post.  These fossils have special importance because they fit into the time period just around two million years ago, which marks the beginning of our genus, Homo, and has been characterized by a relatively fragmentary fossil record.


These new data fit into a long standing general debate in paleoanthropology: how many ancient species were there?  On one side, you have the splitters, who tend to understand physical differences between particular fossils as evidence of distinct species--they split fossils into separate species categories.  On the other, you have the lumpers, who understand the same differences as being simply part of the range of variation expected within diverse and changing populations--they lump differences into fewer categories.  The anthropologists involved in the current story favor the splitter interpretation--early Homo was characterized by at least two species two million years ago.

As I noted last month, anthropology is accumulating increasing evidence of interbreeding between archaic human populations (people living much more recently than early Homo).  In those cases, it seems we had fairly distinct populations, but not quite fully separated species--in the sense that the reproduction of viable offspring is impossible.  I have no special insight into the work described in the links above, but I wonder if such processes were at play during the dawn of our genus--populations of early Homo that differed, but still were not completely genetically cut off from one another.