Sunday, 28 April 2013

Spears and eels: aquatic archaeological contexts in human evolution

Collective sighs are being heard throughout human origins communities right now at the resurgence of the 'Aquatic Ape Hypothesis', bobbing up in the mainstream media again, thanks to its buoyant, sinus-filled head: other wise known as a lot of hot air in advance of a conference on the subject. Brenna Hassett has already come up with a superb and very funny riposte to the renewed interest in the theory, and the fact it basically doesn't stand up at all when substantial evidence is asked of it. Her blogpost, suggesting that the kind of reasoning underlying the Aquatic Ape theory could just as well support one of Space Apes has also, with a little help from me and Tori Herridge, spawned a great hashtag (#spaceape) on Twitter. I want to add a little substance to the fun today, by writing about new research with watery contexts in human origins from a recent conference.


At the European Palaeolithic Conference held in February at the British Museum which I attended, two papers had some connections with water, the first being a report from Nicholas Conard on new excavations at the celebrity site of Schoningen (famous for the incredible spears found there), and the other, presented by Laura Basell and Tony Brown (see end for full author list), looked at artefact distribution and niche reconstruction. Turning on our Jargonese translator, they were interested in why we find stone tools where we do, and whether this actually says anything about hominin behaviour.

Olduvai landscape from space (see, a #spaceape link!). Image: By Darwinek at en.wikipedia [Public domain], from Wikimedia Commons
 Many (although certainly not all) earlier Palaeolithic sites- I'm thinking several million years to about the last 50,000- are connected with water in some way. Even the very ancient Olduvai Gorge locales, which are in dry landscapes today, were in a wetland context near the paleolake Olduvai. In Europe, famous sites like Boxgrove, Neumark Nord, Konigsaue and Lynford Quarry were all situations where we have found large concentrations of stone tools close to lakes, rivers or estuaries. This is on top of the literally thousands of handaxes known just from Britain's river systems, found thanks to a long history of urban building along rivers plus gravel, clay and brickearth quarrying.
 
The Hoxne and Greys Inn handaxes, two of the first stone tools to be recognised as such, both associated with watery contexts. Image: Johnbod, Creative Commons Attribution-Share Alike 3.0 Unported license.

This apparent 'aquatic' connection has led people to wonder if there is a real pattern (although NOT in the manner of the actual Aquatic Ape theory, which talks primarily about biological/anatomical evolution), or whether other factors might be at play, namely the way stone tools are discarded and become part of the archaeological record (known as taphonomy). Certainly watery environments seem to have been attractive to hominins, and perhaps more important to archaeologists, they often acted to preserve very ancient sites in spectacular fashion.

The ability of waterlogged sites to conserve organic matter is the reason for the celebrity status of Schoningen, Germany, the latest results from which Nicholas Conard reported on at the conference. While this site is known primarily for the 8 spears from one level, it is also significant because of its greater richness. Schoningen is a complex of at least 31 separate locales, mostly dating to around 300,000 years ago, which were located at the margins of a lake. The spears were found over ten years ago, and excavations have been continuing since then in advance of the extraction of lignite, or brown coal, because the whole site is actually within an open cast mine. The conditions that acted to form the lignite from organic deposits also preserved the incredible archaeology, leading to what Conard described as a situation with all the benefits of underwater archaeology, without the difficulties.

Spear VII, Schoningen, found in 1997, you can clearly see the finely worked tip. Just imagine digging that up! Image: By P. Pfarr NLD (Niedersächsisches Landesamt für Denkmalpflege) [CC-BY-SA-3.0-de], via Wikimedia Commons
 Aside from the WOW factor of the jaw-dropping throwing spears, first published in 1997, Schoningen is an exceptional site because of the wider preservation of organic remains- other wooden objects have been found including a possible tool haft. In addition, more than 17,000 remains of animals have been recorded. Most of these are from one locality, Scho 13 II-4, much more excitingly known as the Horse Butchery Site, where the remains of around twenty horses were found in association with some of the spears. Importantly for archaeologists, many of them preserved the cutting marks created by hominins tools when butchering carcasses, which gives vital information on ancient subsistence and social practices (hunting and eating meat are inherently social enterprises). There are still hundreds of square meters left of the spear horizon to excavate, with astonishing finds coming out all the time giving clues to the wider landscape and environmental setting of the lake, including fish bones, egg shells and even insect wings.
 
Situation of the Schoningen excavations. Image: By Tangelnfoto (Own work) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
 Excellent preservation also permits very sexy techniques to be used to further uncover what hominins were doing aside from hunting and butchering carcasses, with early results from residue and use-wear analysis on tools showing working of wood, hides and plant processing. Furthermore, detailed analysis of the relationships between bones, stone tools and the structure of the site will help determine whether the Horse Butchery Site records one big hunting event of many horses, or instead, repeated visits by hominins to the same place. Since 2008 researchers have been digging for 10 months of every year, with find spots apparently being uncovered almost everywhere the mining machinery starts to work. Conard estimated that perhaps another 30 years of excavations lie ahead, with undoubtedly more Palaeolithic treasures to be revealed

In contrast to the incredible details and stunning preservation of Schoningen, the research Laura Basell and colleagues talked about at the conference focused on larger scale models of hominin behaviour and how it might link to environmental context. Their paper asked whether the apparent focus of sites on aquatic contexts including lakes, rivers and floodplains in the earlier Palaeolithic record is real or not, and reported on their work on the distribution of artefacts in the south west of England. In fact they did find that a very high proportion of all find spots are from ancient valleys and floodplains, as opposed to on higher ground. Previously people have suggested that it is a matter of visibility: more excavation goes on in the lower level areas of the landscape, both from recent settlement and quarrying, so might we not expect many more stone tools to be found in valleys?

Blackdown Hills, South West England. Freisan cows are not accurate fauna for the Palaeolithic. Image: Sealman. Usage, CC-BY-SA-3.0, via Wikimedia Commons

However Basell and colleagues contend that this bias is a real signature reflecting where hominins were active, rather than an accident of taphonomy: when surveys are done looking for artefacts in uplands, they are not found in anywhere like the same quantities. To explain this, they created a 'nutriscape': a model of the region in question, the Blackdown Hills, examining where the resources most useful to hominins might be found, specifically in the kind of temperate environments they were living in during the Palaeolithic. The result of this nutritional model confirmed that valley bottom environments, followed by clearings on slopes and lake margins, contained the greatest amounts of micronutrients, such as vitamins and folic acid, which are absolute requirements of hominins to include in their diets. In particular, in order to prevent protein poisoning from eating too much lean meat, maintain vitamin C levels, and to get essential carbohydrates and fats, you could eat raw meat, plus internal organs like the liver. Or, you could eat other foods rich in these substances, found in valley bottoms such as nuts, honey and aquatic resources- apparently eels offer an exceptionally well-balanced package of nutrition for hominins!
On the other hand, at present there is no direct evidence for consumption of these resources, and anyway, couldn't the large amounts of tools present in valley bottom gravel deposits be accumulated there by being washed down rivers? Here Basell et al called on new research suggesting that our previous models of high energy rivers being able to move tools long distances are in fact flawed; instead, they claim, most artefacts found in gravel or river contexts have not moved very far from their original place of deposition. This is all intriguing stuff, and while I'm not sure that they took into account the possibility of artefacts moving down hill slopes due to erosion, rather than down rivers themselves, it's great to have big ideas like this aired at conferences because it is attempting to test long-standing large-scale pattern of human behaviour in the environment.

Everything a hominin needs to stay healthy? Image: JanesDaddy [CC-BY-SA-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons


So, here ends this brief foray into current research in human origins with an aquatic, but decidedly not Aquatic Ape, theme. I hope it's clear that water has indeed played a significant role in human evolution, providing a rich environment with many resources that were probably persistently attractive to hominins through varied climates and environments. It has also been incredibly important in helping us to find out about our deep past, through its ability to preserve the real richness of Palaeolithic life in a way that is not possible in most open landscapes or caves. I didn't even talk about the Neanderthal site of Konigsaue, another German lignite locale, which preserved birch bark pitch pieces used to create hafted tools (something I've written about). I'm keeping my fingers crossed for a wetland Neanderthal site on the scale of Schoningen, which is something I'm sure is lurking somewhere, waiting to be found.


[Affiliations: Nicholas Conard is at University of Tubingen; Laura Basell is at Bournemouth University and Tony Brown at University of Southampton. Co-authors of their paper who did not present were Rob Hosfield and Phil Toms, at Reading and Gloucester.]
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