March 10, 2004
Hominid News

Scientific American is carrying this somewhat technical summary of recent fossil discoveries in Ethiopia's Middle Awash region. Some scientists are arguing that a handful of fossil teeth provides evidence of a much more diverse set of hominids during the late Miocene than was previously thought.

Ok, "real people" explanation: apes evolved during the Miocene epoch (a nice overall summary is here). Somewhere between 5 and 10 million years ago (mya) a set of apes evolved fully bipedal locomotion, for reasons that are still unclear*. When climate change destroyed the gigantic Euro-African forests that apes evolved in, some of these bipedal forms (species) struck out onto the savannah to make a living.

Exactly how many species made it out is also unclear and the subject of a growing debate. Regardless, the various species created what seem to be only two strategies for survival: scavenging and grazing. Both strategies were quite successful at first. The grazers grew larger and larger over time, eventually ending up with a species currently known as Paranthropus bosei (I learned it back when it was Australopithecus bosei), a creature with a huge bony crest on its skull and molars more than an inch long.

The scavengers also became more specialized, growing taller and more lightly built (compared to the grazers). The protein content of their diet was presumably what allowed the development of ever larger brains, gradually changing a scavenging model to one of hunting.

At this point, about 1.5-2 mya, there were at least two, perhaps as many as four, different families of erect walking apes on the savannahs of Africa. Homo (us), and Paranthrapus (the huge grazers) are the ones I learned about. Again, for reasons poorly understood, the grazer forms died out at around this time while the hunter forms exploded (perhaps several times) out of Africa and into the Eurasian landmass. They eventually turned into, well, us.

So what these scientists are arguing about is just how many species of erect walking ape there actually were before the forests receded, and which one evolved into us. The big problem is the complete lack of fossils covering this period. They're arguing over six teeth because six teeth is just about all that's been found in Africa from around this time (6-10 mya). However, the discovery is in and of itself a very promising sign, because until recently as far as anyone knew there were no places to find Hominid fossils from this time period. The Awash region is an extremely remote and primitive area, and dangerous to boot with various rebel and bandit clans roaming it at will. Future discoveries will be hard won, but hopefully will come anyway.

Posted by scott at March 10, 2004 09:46 AM

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Comments

hmmmm I wonder when they changed the name for the bosei..cause they were still Australopithecus when I was in school six years ago.

Posted by: carrie on March 10, 2004 11:52 AM

The whole field is apparently in flux again. The naming thing is "out there" enough that it's quite possible you just happened to be reading books from people who didn't think the name should be changed. I think it was the Leakys pushing it. *shrug*

Posted by: Scott on March 10, 2004 12:07 PM

True but know that I think about it, it could be more on a theory that these hominds were not of the same genus. That the split happened much earlier than previously thought. I bet there was something that was discovered recently in the fossil record to show this.

Posted by: carrie on March 10, 2004 12:51 PM

I'm in school right now and it's still called Australopithecus Boisei.

Posted by: Marty on April 22, 2005 01:36 PM
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