Tuesday, February 20, 2007

The Bones Talk

Often, reading about some particular fossil or artefact makes me wonder how it came to be, and causes me to imagine an answer. ~ Jean M. Auel

The bones keep on talking to us ...

We Didn't Kill the Terror Birds

We're off the hook for another extinction. The “Terror Bird”, Titanis walleri, is often depicted as being a contemporary of sabre-toothed cats and mammoths and has long been thought to have gone extinct around 10,000 years ago. Titanis was a resident of North America, so, since this time frame coincides nicely with the arrival of humans on the continent, those early hunters were given at least part of the blame for having killed them off. It turns out we were way too late.

According to a U.S. team who studied rare earth elements within Titanis bones, the Terror Bird finished its terrorism about 2 million years ago, long before any hominids were doing organized hunting. But that wasn't all that the team discovered.

It had been assumed that the birds had migrated from South America to North America about 3.5 million years ago, using the Panamanian land bridge. It now looks as though they showed up about 1.5 million years earlier than that. This raises some serious questions because Titanis was flightless, and 5 million years ago there was water between North and South America. So how did they get here?

That remains a question for more research. It's possible that they could have floated across on natural mats, or they could have been decent swimmers. There is evidence that there were many volcanic islands scattered between the continents. It's possible that these carnivorous canaries could have swum the distance from one to another until they arrived in the north.

Another Possible Neanderthal-Cro Magnon Hybrid

As any reader of this space knows, I think the ongoing fascination with Neanderthals is almost as interesting as the people themselves. Once again, the idea of interbreeding has been raised, this time by a skull found in Romania. The skull has both modern and Neanderthal features and brings up the romantic notion again that we may have Neanderthal ancestors.

It is a slippery slope to find an ancient skull with a flattened face and other Neanderthal sorts of morphologies and extend that evidence into Cro Magnon-Neanderthal nuptials. The fact remains that no evidence of Neanderthal DNA has been found in ours, so, if there was interbreeding, it was either extremely limited, or the offspring were sterile hybrids.

The evidence is very thin so far. What is needed is DNA evidence from one of these skulls showing modern and Neanderthal properties. Unfortunately, it is often hard to get samples for DNA testing from such old skulls. Teeth are the best bet for DNA, but generally the skulls are incomplete or as in this other case, the fossil itself has not been carefully enough handled to prevent contamination.

The Return of the Hobbit

It's been a long time since I've written about the dwarf humans, regrettably known as Hobbits, found in Indonesia. At that time, conventional thinking seemed to be leaning toward the single skull that had been located as belonging to a microcephalic individual. This didn't sit well with the discoverers of the bones, but it was hard for them to refute because of two things. First, although they had bones of several small hominids, they had just the one skull. Second, it seemed unlikely that a creature with a brain that small could be responsible for the tools that were also found at the site.

Initial analysis of the brain case of the Hobbit seemed to confirm that it was a victim of microcephaly. A new study, though, claims to show that the brain, while decidedly smaller than mere dwarfism would require, does not appear to have characteristics consistent with microcephaly. So, what do we have here?

The answer is that no one is quite sure. Dean Falk, who conducted the newest analysis claims that the brain must have been “rewired and reorganized” so that the Hobbits could essentially do more with less. We need to keep in mind that, while Professor Falk's study does not indicate abnormality, it is something of a jump to say that the Hobbit's brain could have produced the tool-making technology evident in the finds.

If, in fact, Professor Falk is correct, though, it forces us to look at the evolution of the brain differently, because nothing like the Hobbit's brain has shown itself in our evolutionary history before.

Ah, science. The more we find out, the more questions we have to answer.

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