Saturday, October 19, 2013

Complete hominid skull challenges views on human evolution

The story of a new hominid skull is making its way around various news outlets since it was reported in Science magazine on Friday.  The skull, found in Dmanisi, Georgia, was reported as "the world's first completely preserved adult hominid skull from the early Pleistocene."

This skull is prompting excitement for two reasons.  First, it is considered to possibly be the oldest record of the genus Homo outside of Africa, where humans are thought to have evolved.  Second, it is difficult to classify into a species, as it shares features with three Homo species, namely H. habilis, H. rudolfensis, and H. erectus.  After comparing this skull with the skulls of these other species, the authors of the report indicated that these may not have been separate species at all, but a single species with no more variation than what is seen in modern humans.

From the evolutionary viewpoint, this is not devastating by any means, but it does rewrite the popular view on the evolutionary history of humans.  As with most organisms, it was thought that many species branched off from the ancestor of hominids, producing a wide variety of human-like apes near the beginning of the Pleistocene, about 2.5 to 1.8 million years ago.  All of these species then went extinct prior to or due to various ice ages, save for Homo sapiens, or the modern human.  In light of the recent findings, however, paleoanthropologists are considering that there was not significant morphological separation within the Homo genus, so that there may have only been a single evolving lineage that eventually gave rise to modern humans.

From a creationist standpoint, these findings are not surprising.  Creationists have long considered H. habilisH. rudolfensis, and H. erectus to be fully human, along with other species such as Neanderthals (H. neanderthalensis, or H. sapiens neanderthalensis, depending on who you ask).  These humans were likely those that scattered from Babel shortly after the Flood, when lifespans were long and the human gene pool was more varied than it is today.

This reflects a larger trend within paleontology, in which remains thought to belong to separate species are being united under a single name.  Everyone wants to be the first to discover a new species, so it is no surprise that there was a bit of overzealousness in doing so.  Additionally, the evolutionary view predicts an increase in genetic variation over time, so morphological differences tend to be attributed to speciation rather than variation within the species.  However, the quantitative science appears to be leading in the opposite direction, showing great variability within extinct species.  The creationist readily accepts this, because the original created kinds would have contained all of the variability necessary to give rise to their varied descendants, a process that does not increase the amount of information.  It is to be expected, then, that fossils such as this skull indicate a greater amount of morphological variation within a species than was previously believed.

No comments:

Post a Comment