A Pre-Clovis Find?
I love scientific mysteries of all kinds – ones where competent experts can legitimately disagree on the interpretation of the evidence, and all agree on what evidence would most likely settle the debate. It’s like a cliffhanger of a great mystery series, except you don’t know when the new season will begin. You just have to wait for new episodes to pop up unexpectedly.
One such debate is the question of how and when were the Americas peopled. This is a story of our recent pre-history. Knowledge of this time has not survived to the present, so we have to reconstruct the past from the clues left behind. And it is recent enough in the past that there is likely to be good physical evidence for archaeologists to find.
For a time the Clovis culture was considered to be the first people in the Americas. They likely crossed the land bridge from Asia to North America about 13,500 years ago, and then worked their way down to South America. They are called the Clovis culture because they are defined by the artifacts they left behind – their projectile points have a very distinctive feature that defines the Clovis. They are fluted at the base on both sides – the stone is precisely carved to be made thinner at the base to allow for better hafting to a wooden spear. These points were designed to hunt the large game of North America, like mammoths. Wherever Clovis points are found – you have Clovis culture.
Unfortunately, there are no sites that have both human remains and Clovis points, so we cannot be sure about the genetic heritage of the people responsible for the Clovis culture. This is definitely a site, somewhere out there, waiting to be found. It is possible that the Clovis culture was not the product of a single population of humans, but was in reality a culture that could have spread to different populations. In other words – Clovis may track a technology, but not a specific people. This is an intriguing idea that also makes it all the more important that we find human remains and Clovis points together.
In any case, there were people widely distributed in the Americas from 13,500 to about 11,000 years ago using Clovis technology. This technology then disappears and is replaced by later paleo-Indian cultures. Another mystery is what, exactly, happened to the people using Clovis technology. Did they die out and were replaced by later migrations? Did they become the later cultures, or merge with them? Perhaps they simply changed their tools after the extinction of much of the megafauna of North America, switching to points better suited to smaller game.
Another question is whether or not the Clovis culture truly represents the first people in the Americas. Is there any evidence of a pre-Clovis culture? Now a new find adds potentially significant evidence to the claim that there were pre-Clovis people in the Americas.
A large find of stone tools and evidence of tool crafting was found north of Austin, Texas – over 15,000 individual pieces of stone. They are largely small tools, which has led archaeologists to suspect that this was a mobile assemblage – made to be picked up and carried. Most importantly, the tools date to about 15,000 years ago, a full 1,500 years or more before the earliest Clovis culture.
In addition to the dating, the find is located beneath a later Clovis site. If the arrangement of these finds represents that order in which they were deposited (and not later mixing) then the tools farther down must be older than the Clovis points found further up.
That is the straightforward interpretation of the find, and by all accounts the authors did a thorough job of presenting their data. Of course, the interpretation of this evidence is not without its controversy also. Other scientists have done their job by thinking of all the possible weaknesses in the evidence.
According to interviews done by the BBC it has been pointed out that the dating method used, optically stimulated luminescence (OSL), while considered a reliable dating method may not be as accurate as carbon dating. If the dates are off by a couple thousand years then this would not be a pre-Clovis find.
Further the assigning of the tools from the two layers to Clovis and non-Clovis can be questioned on the basis that neither contains the projectile points that are diagnostic of the Clovis culture – they contain only other kinds of stone tools.
Perhaps most problematic is that the tools were found in a flood plain. They are buried in clay, which is a good thing in that the clay is hard and not easily disturbed. So from that point of view there was probably not later mixing of the dirt layers. But the clay also indicates that these tools may have been deposited in their current location from somewhere else by flood waters. If the tools were moved around by water, then their relative positions may be deceptive.
While this is clearly an important find, scientists will need to carefully examine the evidence and explore alternate theories before we can know what the definitive answer is.
From reading the article and interviews I was also left a bit confused as to the current status of the theory of a pre-Clovis population in the Americas. From my discussions with archaeologists it seemed to me that the pre-Clovis theory was speculative and not confirmed. However, some of the archaeologists interviewed for the BBC report indicate that the “Clovis-first” hypothesis is dead, and that other sites already clearly establish the existence of pre-Clovis people in the Americas.
I often find it challenging to find out what the consensus is within a specialized field – it seems like you will get a different picture depending on which experts you talk to. What is clear is that there remain two schools of thought regarding pre-Clovis people in the Americas. As an outsider, I am currently unsure which side has the upper hand, in terms of evidence and consensus.
It does seem likely, given how testable the claims of each side are, that eventually opinion will yield to more definitive evidence.
Do we have the technology to assess the topology of the area at that time? If so, I would start my search at the nearest source of fresh water.
I just hope they don’t uncover a crocoduck fossil…
Hey, I love it when you guys talk about archaeology on SGU. If you get any chances to interview an archaeologist again, I would love to listen to the latest news in that field.
An interesting theory in connection with the Clovis points is the Solutrean hypothesis (http://en.wikipedia.org/wiki/Solutrean_theory). Some archaeologists have noticed astonishing similarities between the points Clovis points and those found in France. For more information there was also a PBS Nova documentary (http://www.pbs.org/wgbh/nova/stoneage/) Where they talk about it more in depth. I’m a bit skeptical of this theory because there is scant physical evidence. However, little evidence would be left behind, so its fun to think about, but a bit of an extraordinary claim.
From my experience most archeologists are very conservative when it comes to defending existing models of population movements and settlement.
New ideas are often not only not openly discussed but shunned. It takes archeology typically more time to accept even well evidenced new research than other sciences. And the fights can be very dramatic.
Although there is some evidence that other than just people from beringia settled the Americas, it took some time for archeologists in NA to accept the fact that the northern migration route might not be the only one to people the Americas.
here some references to pre-clovis culture
http://www.sciencedaily.com/releases/2008/04/080403141109.htm
http://hoopermuseum.earthsci.carleton.ca//beringia/preclovis.html
http://chattahbox.com/science/2009/11/06/oregon-caves-yield-rare-pre-clovis-artifact-14230-years-old/
Exactly. Stoneycroft in Pennsylvania, the Chilean finds. The “Clovis first” POV, unlike what one might infer from Novella’s worry about non-carbon datings, by no means hinges on the accuracy of dating this find. And per Patrick, one of the researchers of this site, on ScienceFriday last week, while not singling out Solutarians, did talk about the “multiple origins” theory in general.
We plan to interview an archaeologist for this week’s SGU to cover this story.
One slight “bone to pick,” Steven, per a comment of yours above:
Speaking logically, not only does such wishing not guarantee such a site will be found, it doesn’t even guarantee it exists; there’s no logical necessity for such a site.
Pedant,
Would the substitution of “almost certainly” for “definitely” satisfy your neurosis? Unless these people immolated their dead and ground the bones into dust, there is “almost certainly” a bone still in existence somewhere. And, if it exists, it is “waiting to be found”.
I think the point SocraticGadfly was making is that ancient humans were nomadic — they moved around to follow the animals they hunted. There is no reason they would bury their dead in the same areas where they might spear an animal. Thus there is no necessary reason to believe that there will be a site where both human remains and stone tools will be found. It is possible of course, but it doesn’t necessarily have to exist.
Thanks, Al, and yes. I wasn’t being pedantic.
In fact, I think the likelihood of the same spot being a site for both a notable Clovis and a notable pre-Clovis find is pretty small. Over 2,000 years, even without too much human influence, general migratory and environmental changes would both work against that.
And of course the question of North American migrations and origins are so politically fraught that I suspect archaeologists are just uncomfortable with anything that might attract attention.
Listening to the story on the BBC Science in Action podcast today I was struck by how the archaeologist interviewed was long critical of the Clovis-First theory, went looking for evidence against it, and finally found the perfect pre-Clovis site.
It seems plausible to me that there is a large amount of confirmation bias involved, and the evidence is in actuality less compelling than the initial researchers find it.
Nope. See above, Peter, and my response. This is just the last nail in the Clovis-first coffin.
Is there any estimate on how much time these migrations took? Is it over multiple generations? It’s interesting to think of how often and how far any one group might have moved and what motivations they might have had.
Jacob, you can Google and find estimated migration rates of the first Americans, and of hunter gatherers in general.
One quasi-historical example, so called because they come in at the beginning of the Spanish Entrada — the Navajos and Apaches moved to the U.S. Southwest from North Central Canada in what is estimated by many to be well under 1,000 years.
Scientists are human. There, I solved the controversy. You can thank me later.
You should list your references to legitimate this outrageous claim!!
I don’t see the point of comparing the dating technique to 14C dating. 14C dating can only be done if there are contemporary plant or animal derived items in the dig (half-burnt firewood, bones, etc). A better statement would be “technique X is only good to within +/- Y years”.
I’d like to see a summary of what other evidence there is for pre-Clovis habitation. It’s a pity there weren’t enough large volcanic eruptions in that relatively short period of time – that would make it considerably easier to establish the absolute age of the soil at different depths. Unfortunately the tools themselves don’t offer too much since the rock they are made from are all ancient (and so the fluorescence technique is about the only means of gauging when the tools were fashioned).
Mad, IIRC, the Oregon site DID have C14 dating. Otherwise, look above at those links Peter mentioned. Or just Google “pre-Clovis” or “Stonycroft.”