Overhyped Study Shows Neanderthals Were Not Trees
Saturday, February 9, 2008
Above: The GEICO Neanderthals are sick of people underestimating them.
I do not normally comment on isotopic studies in paleoanthropology (in part, because there are so many of them these days that it's hard to keep up with the recent developments and claims), but this particular study produced findings so lackluster but so overhyped in the news that I felt compelled to post about it. I was excited to see the headline "Tooth Scan Reveals Neanderthal Mobility" on Yahoo's "most popular stories" list -- it is always good to see anthropology in the news (so long as the story isn't entirely inaccurate or doesn't totally miss the point). The problem here, though, is that the findings are not at all surprising, but the researchers contend their study shows Neanderthal society was more complex than anthropologists widely think. This story, though, was turning up on every news site (Newsweek, USA Today, etc) and even the local news as a big discovery.
Let's take a look at the article -- I'll add comments as we go...
Tooth Scan Reveals Neanderthal Mobility
By Elena Bacatoros, Associated Press
Analysis of a 40,000-year-old tooth found in southern Greece suggests Neanderthals were more mobile than once thought, paleontologists said Friday. . .
That is great! There has been a lot of discussion recently about Neanderthal mobility, resource procurement strategies, territory, population density, frequency of contact with our ancestors, etc. This could be important!
Analysis of the tooth — part of the first and only Neanderthal remains found in Greece — showed the ancient human had spent at least part of its life away from the area where it died.
"Neanderthal mobility is highly controversial," said paleoanthropologist Katerina Harvati at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Some experts believe Neanderthals roamed over very limited areas, but others say they must have been more mobile, particularly when hunting, Harvati said. . .
It is true we don't know the exact range that a band of Neanderthals would've routinely had. My understanding is that Neanderthals' territory was notably smaller than that of early modern humans. One of the best indicators we have available for estimating territory size is the stone-tool evidence. Neanderthals' stone tools are usually found within 50 kilometers (about 30 miles) of their raw-material source. This offer us with an upper limit for a resource-procurement territory, or at least a good estimate of one. It would be significant if their fossil evidence suggested that Neanderthals had a range much greater than 50 kilometers (30 miles). Let's continue...
Until now, experts only had indirect evidence, including stone used in tools, Harvati said. "Our analysis is the first that brings evidence from a Neanderthal fossil itself," she said. . .
I'm not sure this should be considered entirely accurate. Various researchers have been looking at Neanderthal anatomy to estimate their mobility in comparison to early modern humans. The shape of the femur (i.e., shorter legs adapted to the cold) has been a particular focus of such studies. But this isn't important... Or is it? Often, I have found, when some researcher states "This is the first application of the technique in archaeology," they are usually wrong and the study is often lackluster and preliminary in order to be the one publicized first. Maybe this claim here should also be a warning sign, after all, it is already not entirely correct.
The findings by the Max Planck Institute team were published in the Journal of Archaeological Science.
The tooth was found in a seaside excavation in Greece's southern Peloponnese region in 2002...
Wait, this is just one tooth? One? Well, perhaps this will still prove interesting.
Wait, is this just a lone fossil tooth found by itself? No body or burial? How do we know that its recovery location was where the individual died? The tooth could have been lost naturally or due to injury or infection. It could also have transported by other Neanderthals or by geologic processes (transport by erosion, water, etc). Certainly the tooth could be moved geologically several miles over the course of 40,000 years.
Oh well, it might still offer a new and notable data point in this debate...
The team analyzed tooth enamel for ratios of a strontium isotope, a naturally occurring metal found in food and water. Levels of the metal vary in different areas...
True, strontium vary spatially as a result of geological processes. Strontium easily substitutes for calcium within many common minerals (calcium carbonates, feldspars, etc.) as well as teeth and bones. As a consequence of water-rock chemical reactions, strontium is almost always present in groundwater at some concentration. There are several isotopes of strontium. Sr-88 is the most abundant isotope (over 82%), followed by Sr-86 (9.9%) and Sr-87 (7.0%). Sr-84 accounts for about half of a percent of strontium atoms. Most researchers are interested in only two of the strontium isotopes: Sr-86 and Sr-87. The latter is a daughter isotope of Rb-87 radioactive decay, and rubidium is also linked to rock chemistry because it readily substitutes for potassium. This means that rocks rich in potassium- and calcium-rich minerals will have a different isotopic signature that rocks without them. The groundwater, in turn, from different geologic areas has different isotopic signatures. There is also variation over time due to ocean hydrothermal activity, erosion of continental rocks, etc. -- therefore old rocks and young rocks have distinct strontium isotope ratios. All of this variation is used to try to recognize a "signature" for a particular geologic setting based on measurements of the strontium isotopes in bones or teeth. This requires, of course, a suitable geologic record for the landscape hundreds of thousands of years ago.
There is also a concern about isotopic "averaging" for a nomadic group. What happens to the isotopic ratio in a tooth if its owner spent time in different landscapes during different seasons? Does it have an "average" ratio of those areas, or can the researchers identify isotopic variations on a yearly timescale? What would a ratio be for Neanderthals who summered in the mountains and wintered near the ocean?
This isn't a major issue for this study, though, because we're hoping for a new maximum range estimate...
"Our findings prove that ... their settlement networks were broader and more organized than we believed," Panagopoulou said...
This ought to be really good! Evidence that challenges current mobility estimates! Will the new measurement corroborate the 30-mile estimate based on the stone tools? Will it suggest a much greater distance? Will it be more like the estimated range of early modern humans, whose stone tools come from over 100 miles away? It would be really impressive if that were true. But maybe it will still be less than that, like 50 miles...
Eleni Panagopoulou of the Paleoanthropology-Speleology Department of Southern Greece said the tooth's levels of strontium showed that the Neanderthal grew up at least 12.5 miles from the discovery site.
What?! Less than 13 miles? Over several years? That's it? They probably walked that far in only a week while hunting and gathering. How does this demonstrate "their settlement networks were broader and more organized than we believed"? We have better (and a lot more) evidence based on sourcing their stone tools, showing their settlements were ordinarily 30 miles or less from the sources of their raw material. And that is just the maximum distance they felt like carrying rocks! Ethnographic studies (i.e., Lee 1968; Vita-Vinzi and Higgs 1970) show that modern hunter-gatherers didn't usually travel more than 10 kilometers from the base camp, but that is merely for their daily subsistence practices, not seasonal (or lifetime) movements... and that's just an average. The Hadza, according to Woodburn (1968), used an area of 63 square miles with a radius of 4.5 miles for a band of 25. The Caribou Eskimos, though, needed a territory of 2500 square miles with a 28-mile radius for the same number of individuals. This still doesn't reflect movement over a long period of time, though. Nor does it take into account movement among groups (an individual leaves one band and joins another), groups merging and/or separating, territory changes due to warfare or other external pressure, and other factors.
Perhaps because I am not a Neanderthal researcher, I am unfamiliar with all of the debates about their mobility, and perhaps there has been a plethora of evidence or arguments suggesting that Neanderthals never ventured more than 12 miles from camp. But based on lithic evidence, it appears that Neanderthals routinely travelled as much as 30 miles from their settlement to collect stone in order to make tools. By comparison, the fact that one Neanderthal individual travelled 13 miles during their lifetime isn't very significant.
I'm not the only one who feels let down -- Dr. Clive Finlayson is quoted as being similarly unimpressed:
Clive Finlayson, an expert on Neanderthals and director of the Gibraltar Museum, disagreed with the finding's significance.
"I would have been surprised if Neanderthals didn't move at least 20 kilometers (12.5 miles) in their lifetime, or even in a year ... We're talking about humans, not trees," Finlayson said.
Hence the title of this post: these researchers have proven Neanderthals are more mobile than trees.
Dr. Finlayson made another very insightful comment about this study:
"The technique is interesting, and if we could repeat this over and over for lots of [individuals] then we might get some kind of picture," he said.
Exactly... I'm not saying this is a bad study or that their result is inaccurate. However, it was inaccurate to assert their study was the first to consider fossil evidence in Neanderthal mobility -- it may or may not be the first to use strontium isotopic data from fossils to investigate this question, but physical anthropologists have been working a long time trying to glean clues about mobility from Neanderthal fossils, especially their femurs and hips. It is also misleading to contend that knowing one Neanderthal individual travelled 13 miles during their lifetime proves that "their settlement networks were broader and more organized than we believed." As Dr. Finlayson noted, the real surprise would have been learning that Neanderthals did not move 13 miles during their life. Archaeologists and biological anthropologists have found much evidence (from their stone tools and grave goods to anatomical traits and DNA) of Neanderthal sophistication, so this new study should be no surprise.
The GEICO "cavemen" (who I consider to be Neanderthals, while others consider them to be Cro-Magnons) are offended by the slogan "So easy, even a caveman can do it" and the widespread belief they are dim-witted. The cavemen find that humans continuously underestimate their sophistication. How would the cavemen respond to implications that their ability to travel 13 miles over their lifetime is surprising? I imagine that the picture above is pretty much what they'd do. In the words of the first GEICO caveman: Not cool.
Blog Author: Ellery Frahm