Thursday, October 17, 2013

Remarkable variation seen in Skull 5 from Dmanisi

The tiny village of Dmanisi in the former Soviet republic of Georgia has been the site of some amazing fossil discoveries in the past decade or so.  The fossils are conventionally dated to about 1.8 million years ago.  Some have placed them in a separate species (Homo georgicus), while others contend that they're part of the Homo erectus complex.  This week's Science reports on another skull from the same locality.

What makes them interesting, though, is not the labels pasted on them, but the wide variation all from the same locality.  Some of the skulls, like Skull 4, resemble Neandertals or even modern Homo sapiens, while Skulls 2 & 3 were more like the classic Homo erectus.  Skull 5, though, is quite different, more like the so-called "early Homo" like H. habilis.  Skull 5 has a projecting muzzle and a much lower forehead than the other Dmanisi skulls.

What makes these skulls really interesting is the occurrence of all of them from one locality and (roughly) from one time period.  If they were found in other regions or other rock layers, you could easily string them together to make a phylogeny, but here they are in one location.  So are they different "kinds" all living in one spot?  Ecologically, that's hard to understand.  Similar species like that don't tend to occupy exactly the same locality in our modern world.

Or could these skulls represent a much more variable humanity from the immediate post-Flood world?  My own understanding of post-Flood biology would suggest that populations recovering from the Flood were much more variable than they are today.  As organisms dispersed across the globe, biological lineages stabilized into the species we know today, but during that earliest time after the Flood, I imagine that families could be hugely variable.  Could Dmanisi represent that kind of variability?  Could Skull 5 then add credence to my contentions that early Homo (and even A. sediba) were really human?

It's definitely interesting reading, so check it out if you can:

Lordkipanidze et al.  2013.  A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo.  Science 342:326-331.

Feedback? Email me at toddcharleswood [at] gmail [dot] com.

(Photo: from Science)