The Not Quite Adventures of a Professional Archaeologist and Aspiring Curmudgeon

Monday, March 28, 2011

The Oldest Site in North America?

You may have read that the oldest archaeological site in North America has been found. Again. This story gets repeated every few years, as an archaeologist finds a site that shows some sign of having been older than the Clovis-era sites that are usually thought of as the first sites in the Americas.

This time, however, they may be correct.

The Clovis culture is the term given to what appear to have been small, highly-mobile bands of hunter-gatherers who produced distinctive "fluted" (the hafting end is thinned by a channel on either side, allowing for easier hafting) spear points. Sites from the Clovis culture have been found throughout North America, and seem to have appeared out of nowhere around 13,000 years ago. In this case, a paper that appeared in the journal Science documents a claimed pre-Clovis site in Texas.

There have been numerous articles produced which purport to show that a site pre-dates Clovis, and the sites that are the subject of these articles become briefly controversial, and then fade away when the evidence is more closely scrutinized...with a couple of notable exceptions (which, while not definitive, are interesting). As a student, I was energetic the first few times that I heard these findings announced, but as they continued to come to nothing, my enthusiasm flagged. I am still interested when I hear such announcements, after all, this could be the real deal this time around, but I am much more cautious in my acceptance of such claims. Now, there are hot emotions amongst archaeologists regarding this subject, so first and foremost, you need to understand something about where I am coming from - the results reported by the authors, if confirmed to be true, would not surprise me. I am one of the archaeologists who thinks that there were "Pre-Clovis" people in the Americas - after all, the Clovis tools seem to appear out of nowhere with no clear old-world antecedents, so it seems likely that their predecessors were kicking around for a little while before the ol' fluted points came into being. However, that doesn't mean that I'm going to accept poor data to back up the argument that I think is correct. In other words, I have no problem buying that there were pre-Clovis people, I do have a problem with dubious data supporting a position, even if it's a position that I agree with.

But this appears to be the real deal. There are multiple lines of evidence from the placement of the artifacts within the site, and their relationship to Clovis-era artifacts in a higher level of the site, which indicate that they are older. And the clays in which the tools were found were dated using a technique called optically stimulated luminescence (OSL) (follow the link for a description) by which the date at which a crystalline material was last exposed to sunlight can be determined.

I'm persuaded, but I will admit that I am reluctant to completely throw my hat in with the research results just yet. I have to admit, though, that my reluctance comes in no small part from the fact that so many of these claims have turned out to be either false or of more dubious quality in the past, and I don't yet trust this one completely. In other words, there's more emotion than rationality in my reluctance.

There are two things that need to be noted about these results, though: 1) the clay around the artifacts was dated, not the artifacts themselves, and 2) the dating technique used is a relatively new one.

So, for point #1 - Dating techniques applied to materials that are not artifactual in nature, that is not man-made, are often tricky to apply to artifacts. The authors of this article appear to have taken great care in evaluating the nature of the sediments in which these tools were found, and they have used multiple lines of evidence to argue that the sediments have not been exposed to sufficient amounts of disturbance to allow the artifacts to have been moved in such a way as to cause confusion. However, while I know enough about stratigraphy to follow the discussion and say that it sounds solid, I am not a geomorphologist, and they might have some criticisms that I am not aware of.

#2 - The dating technique is a new one. It sounds plausible to me, not being a physicist or a chemist, and I am not accusing the authors of the article of using a poor method or applying it badly, in fact everything that I have read indicates that it is a very good method. However, OSL as a dating technique has really emerged in the last decade or so, and there may be some bugs to it that we are not yet aware of. So, again, this work sounds solid, and I have no problem accepting it provisionally, but keep your eyes open for the discussion of the validity of the dates, as there is a fair chance that we will hear more about this.

A third point should also be raised - everybody wants to be the hero. Every now and again, someone asks me what the "Holy Grail" of North American archaeology is, and I usually respond that there isn't one, but that's not entirely true. The search for the oldest site in the Americas is something of an obsession amongst many of my colleagues**. For this reason, it's not uncommon to see an archaeologist, with the best of intentions but more than a bit of the grail-knight's zeal, report data asserting that they have found the oldest site in the Americas without taking into consideration some element of the data that might place some doubt on the result.

You can see some of this zeal in the way that this site is being reported: a press conference was called before the paper could be widely-read by other archaeologists, and one of the report authors, Michael Waters, was talking about this site in bombastic terms:

This is almost like a baseball bat to the side of the head to the archeological community to wake up and say, hey, there are pre-Clovis people here . . . and we need to develop a new model for peopling of the Americas.

So, there's every reason, based on the behavior of the team, to think that there may be enough enthusiasm to lead to them jumping to conclusions.

At the same time, a number of sites in both North and South America have produced dates in the range of 14,000 to 16,000 years before present. Some work on the genetics of the first settlers of the Americas has produced similar dates. These dates have been somewhat problematic, and none have been widely accepted as of yet, but it does seem to be consistent with a growing amount of data pushing the colonization of the Americas back earlier than originally anticipated. So, the enthusiasm of these researchers is, perhaps, earned.

So, is this the oldest confirmed site in North America, and solid proof of Pre-Clovis people? Maybe. Hell, I'll go so far as to say that it probably is. But, I would also caution that there is likely to be some continued scrutiny of the techniques used and the deposits dated, and that the issue isn't settled just yet.

Still, it's an exciting time to be an archaeologist.

*Understand, though, that I mean that I suspect that humans had arrived in the Americas at some point before the Clovis tools began production. It may have been a century, it may have been a few thousand years. I am not supporting the rather loopy assertions that pre-Homo sapien homonids were in the Americas. Those arguments have been made, and continue to fail, and the burden of proof lies with the proponents of that one.

**myself, I am more interested in culture change over time, and so later sites with better preserved components and a decent ethnohistoric record tend to be of more interest to me. The early stuff is interesting, and I enjoy reading about it, but it's not a particular passion of mine.

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