Thursday, November 14, 2013

Georgia Cavemen: Clarification or More Confusion?

I read this article in the original Science magazine, but I am forced to blog this off this news wire report because of the paywall at Science. I regret that the two citations differ in significant facts, but I choose to believe Science.

Note: Cave girls not much like Homo georgicus
‘Homo Georgicus’: Georgia skull may prove early humans were single species
A 1.8 million-year-old skull found in Georgia could turn current understanding of evolution on its head. A new study claims that early man did not come from Africa as seven species, but was actually a single ‘homo erectus’ with variations in looks.

The case revolves around an early human skull found in a stunningly well-preserved state at an archaeological dig at the site of the medieval hill city of Dmanisi in Georgia, a study in the journal Science revealed on Thursday.

Stone tools were found next to the remains, indicating that the species hunted large carnivorous prey, including probably saber-toothed tigers.
This is where the two articles differ very much.  According to Science, all 5 skulls were found in caves that were the former lairs of large feline predators, sabertooth 'tigers' or giant cheetahs.  So these Georgian cavemen were more likely prey than predators.  Which is not to say that the cavemen might not have managed to kill few in return.

Back then, Eurasia offered a fine collection of feline predators, the ancestors of today's lions and tigers, cave lions, leopards, jaguars, the various sabre tooth and scimitar tooth cats, and giant cheetahs (just try outrunning one).
A team of scientists spent over eight years studying the find, whose original date of excavation was 2005. Its jawbone was actually discovered back in 2000, but only recently have the parts been assembled to produce a complete skull.

New dating technology allowed scientists to establish that these early humans come from around 1.8 million years ago. Near to the bone fragments were the remains of huge prehistoric predators; the area is next to a river and was full of them, as they encountered humans in fights to the death.
I don't know how they got there from the science report; just because the bones are there doesn't mean people put them there; the American west and Mongolia are chock full of dinosaur bones that died before people had evolved to kill them.

1.8 million years ago, the earth's was still descending into the worst parts of the Pleistocene Era.  The climate was oscillating between warm and cold on a 41,000 year cycle, compared to the more recent cycles of 100,000 years, with neither the warm nor cold spells as deep as the recent last million or so years. Not the best of times, not the worst of times. Except for all the damn cats, probably a good time to be a cave person.

The skull has a tiny brain about a third of the size of our modern Homo sapiens incarnation; it also has protruding brows, jutting jaws and other characteristics we have come to expect from lesser developed prehistoric humans.

But the surprising revelation came when the skull was placed next to four other skulls discovered within a 100-kilometer radius. They vary so much in appearance that it brings into question whether the current understanding of species variation is correct.

Traditional theories accept a whole plethora of stand-alone species – but the new find strongly hints that the five remains were all one, but with striking differences in bone structure that we have come to expect only from our own ‘complex’ kind.
Which is way too sensible an outcome for scientists to agree on easily:
However, challengers to the hypothesis believe otherwise. Their main qualm with the hypothesis is that the skull may simply have belonged to a new species of human – not a variation of Homo erectus.
Ah, the eternal war between lumpers and splitters. According to the Science article, the authors argue for the name Homo erectus ergaster georgicus, but will settle for it being called "Early Homo."  That pretty much makes them an early candidate for ours and Neandertal Man's ancestors.

Wombat-Socho's grand compilation of Rule 5 posts,  "Rule 5 Monday: Palate Cleanser" is up at The Other McCain.

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