John Gurche, an especially able paleo-artist, has crafted some facial reconstructions of various hominid taxa for a new exhibit at the Smithsonian. They offer a fascinating glimpse into our evolutionary past.
Many paleoanthropologists assert — with good reason — that Australopithecus afarensis (the taxon to which Lucy belonged) is ancestral to later hominids (including Homo). With that in mind, let’s look at A. afarensis:
A. afarensis did not of course remain static over the course of its evolutionary life-time and most likely gave rise to several other species of “gracile” australopiths. Because one of these lineages gave rise to Homo erectus, let’s look at erectus:
Clearly, there was a great deal of change between A. afarensis and H. erectus. This change (or transition) is filled by Homo habilis or Homo rudolfensis. Unfortunately, we do not have any facial reconstructions of these taxa.
While there is much disagreement about Homo habilis (are they australopiths or Homo?), the good news is that the fossils assigned to H. habilis do not look particularly like early forms of A. afarensis and show some “human-like” characteristics that become much more pronounced in H. erectus.
We have, in other words, some nice evidence of a transition rather than the abrupt appearance of an entirely new species. One thing that was surely changing was brain size and morphology. Unfortunately, these changes cannot tell us much about mental abilities. We will never know, in other words, whether H. erectus was able to think about spirit worlds or the supernatural.