Wednesday, February 28, 2007

Furrowed Brows Over Lake Chapala, Mexico

As I've recently written a couple of posts looking at potential sites indicative of a pre-Clovis America, which have concentrated in the higher latitudes, from Minnesota in the north, down through Gault and Topper it occurred to me to look further south, in an effort to get a handle on some of the other sites that are to be found in the lower latitudes, and specifically meso-America.

One of the advantages of heading south in search of ancient human presence is that the ice sheets that had covered much of Canada and parts of North America never extended beyond those regions - meaning that if ancient artifacts or remains were found south of the ice sheets, there would be a much greater chance that they had remained in situ and context, rather than being ground to dust and deposited away from their point of origin by the effects of billions of tons of ice crushing all and sundry in its path.

The Chapala Basin in the western coastal state of Jalisco, in Mexico previously unknown to me, and it is to that location, or more specifically Lakes Chapala and Zacoalco, we travel today, in search of clues that might indicate a pre-Clovis human presence there.

Since the 1950s, F(r)ederico Solorzarno, an anthropologist from Guadalajara, has been excavating at the site which is described as having a fantastically rich assortment of Pleistocene animal remains, numbering over 500,000 specimens, with an exotic suite of fauna represented. Included were antelope, bear, camel, deer, glyptodont, sloth, horse, jaguar, mammoth, sabre-tooth tiger, tapir and wolf, and many more besides. Here's a quote from 'Bones, Boats and Bison'...

"Amongst the vast assemblage of Pleistocene mammal remains are a wide array of spirally fractured, cut, polished, perforated and otherwise modified bone, antler and ivory. While some of these specimens clearly result from such non-cultural events as carnivore fracture and gnawing, others have been modified by humans and some are complete artefacts."

All the specimens, including those that had been modified by hand, were fossilised and stained with a black manganese derived patina, which led Solorzano to conclude that the bones, which he dated to between 50,000 and 80,000 years, must have been modified before the fossilisation process had begun - in effect suggesting that the humans who made the modifications may have been present at Lake Chapala during that 50-80,000 year time-frame.

But the most notable piece of bone came to light one day when Solorzano was sifting through some of these remains in his lab - stained black, and of uncertain provenance, he held in his hand a piece of thick, curved bone, no more than a few inches in length.

Although fragmentary remains of humans, including mandible parts, and separate molars and incisors, have been found there, the piece of bone Solorzano had come across, apparently puzzled him until he compared it with, and found what is described as a perfect match for, the supra-orbital ridge of a European Homo erectus who had been found in a cave in France, known as both Tautavel and Arago.

"Most people sort of just shook their heads and have been baffled by it," said Robson Bonnichsen, director of the Center for the Study of the First Americans at Texas A&M University. "That doesn't mean it's not real. It just means there's not any comparative evidence." That primitive brown ridge from Lake Chapala "is in a category by itself." It is so out of context that it has been largely ignored even as other discoveries are raising basic questions about the story of human beings in the Americas, when they arrived, and where they came from.

Here's some comment on Tautavel Cave from Wikipedia...

"A community of about 100 individuals discovered over the years in the ongoing excavations of the cave by a team of the Centre Européen de Recherches Préhistoriques de Tautavil under the direction of Henry de Lumley. Excavations began in 1964, the first mandible came to light in 1969, and the first "Tautavil Man" in 1971, though in fact many subsequent Tautavil men and women appeared. The date range is a fairly secure 690,000-300,000 ya by many methods. The prevailing view is that the fossils are intermediary to the Neanderthals. Tools were found as well."

As well as the brow-ridge, one of the pieces of jaw-bone also recovered hasn't been found to correspond to any known modern human equivalents - however, whether it comes from the same individual(s) sporting the robust brow-ridge isn't stated, and is probably unknown. I'm not even sure how near or how far these human specimens were found to or from each other. Whether further efforts have been made to compare the jaw fragment with known archaic species isn't mentioned anywhere that I can find - I would imagine that someone would wish to investigate this as a matter of urgency, though it's been over two years since these reports came out, which themselves reflect events that had occurred back in the 1990s, and there is no news as yet, nor any report whether such research is even being conducted.

Although the putative brow-ridge has been compared with that of H. erectus, it might as easily be compared with either H. heidelbergensis or its Spanish counterpart, H. antecessor, both species which as far as I'm aware, have only been found in Europe. Although there have been other discussions as to whether European Solutreans made it to the New World around 20,000 bp, these earlier Europeans date to around half a million years ago and beyond.

Assuming for a brief moment that the specimen does indeed belong to an archaic human, and dates from the same period as the faunal remains at Lake Chapala, i.e. 50-80kyr bp, there are a number of possible candidates - as mentioned earlier, Homo erectus was still extant at this time, although I think this species was by now largely confined to SE Asia. It has been suggested that some early arrivals to the Americas could have travelled in along the Pacific north-western coast - for example Kennewick Man, at a relatively recent 9,500 years, is thought to have had ancestral links from around Japan, where the Ainu people are to be found living today.

Although H erectus travelled across a stretch of open sea to reach Indonesian Flores around 840,000 bp, it's by no means clear if this was by accident, or a planned voyage for which ocean-going boats had been made. However it might be more difficult to come up with a credible account as to how H. erectus could have made it across to north-western America, but theoretically it's not completely beyond the bounds of possibility.

Or if we head back to Eurasia at 80,000 bp and less, we would find the Neanderthals in residence - if however the brow-ridge seems to more closely resemble their predecessors, this would have meant their ancestors getting to America before they became extinct at around 300,000 bp.

So could the brow-ridge have belonged to Neanderthals who had de-camped to the New World from Palaeolithic Eurasia or the Middle East? To do this they would have needed to have travelled up through places like the Arctic Circle and Siberia – and may well have needed an earlier version of the Beringia land bridge to have been in existence.

They could have a theoretical choice of two routes - one, straight across the Atlantic by boat - I'm not sure of what ice sheets may have been around at various points during that era, or taking a land route up through northern Europe, across Russia and into Siberia, or alternatively had headed into somewhere like Mongolia, round the edge of the Tarim Basin, south at the right moment and taken the SE Asia route. (I need to check a good atlas, so this posited route may be invalid.)020307 correction - I'd forgotten I'd left this detail untended. Assuming people travelled as far east, from Europe as far as the Tarim Basin, it's more likely they'd have had to head north east into across the Altai Mountains and thence through Mongolia, up past Lake Baikal and so on.

I mentioned this as a possibility because there is good evidence, dating from just a few thousand years ago, that Europeans regularly travelled this route, heading for places like Urumchi, and it occurred that this route could possibly have been known about and used much further back. Maybe the first travellers along what came to be known as the Silk Road, were themselves archaic people on the move.

I considered China as a possible point of origin for an archaic ingression to the Americas because I get the impression there is good evidence from there of archaic humans in quite large numbers, both there and SE Asia - unfortunately we only seem to get the bare bones of such discoveries in our news from there, but there is a coastal route heading north which archaic people might have followed up into Siberia, but again this is no more than speculative guess work.

However in both cases I should stress that prevailing climatic conditions at the time, between 50,000 and 80,000 bp may have strongly influenced which routes, if any, people took when traversing such large distances - I assume the Taklamakan and Gobi deserts were as inhospitable back then as they are today, and thus would have been avoided by humans.

Hopefully one day we in the West will have a much better understanding of Palaeolithic China and nearby regions - although research is certainly conducted there, it is, naturally enough, undertaken by archaeologists and anthropologists from those regions, and consequently the majority of the reports and analysis are not widely available in English. In any event, it wouldn't be too surprising if there were some major finds and discoveries from that part of the world, which could shed a great deal more light on early human presence there.

I can't imagine archaic people making trans-Atlantic voyages at such early dates - assuming that humans living in Europe were unaware of the American continent that lay far over the horizon, it's unlikely they would have put to sea with the intention of travelling until they made land-fall elsewhere. This is also a problem when considering whether the later Solutreans made western voyages. In both cases it's just possible that they made the journey across, but in the former it's unlikely enough people could have made such a daunting journey to make it a migratory event, and with the latter there doesn't seem much in the way of persuasive argument that would have prompted such long, hazardous voyages to destinations that were unknown.

In a world of infinite ifs and multiple maybes, where data is scant and ideas are few, sometimes all we can do is speculate, extrapolating what information there is to what may or not be a logical conclusion, if only to get such thoughts out of the way for a clearer look at different theories at a later time.

So, does this find from Lake Chapala indicate that even earlier Eurasians were in the New World between 50,000 and 80,000 bp - on the evidence so far, I’d have to give it a rating of a definite ‘maybe’. Although there appears to be at least a visual similarity, there is no certainty that it actually came from an archaic human - according to Dixon, others have suggested it may belong to another animal entirely, although unsurprisingly, no-one has apparently decided what that animal might be.

Obviously if a symmetrically matching piece of bone was located, the case would be stronger - however, the fossil is thought to have been so heavily mineralised with manganese that there is insufficient collagen contained therein to allow for carbon 14 AMS dating, but I’m sure there was a recent breakthrough in C14 dating that might now allow for this specimen to be dated, the manganese saturation notwithstanding.

So for now, ancient Lake Chapala and its ancient residents remain as tantalising clues that hint at a possible archaic human presence in the New World – but until more substantial evidence is gleaned either from the boxes of bone fragments in the lab of Solorzano, the lakeside environment, or indeed the fossil fragments themselves, not much more can be done to advance the discussion.

If left up to me, I’d start checking for caves and rock shelters and occupation levels therein at depths not previously explored – I have no idea of the geology of the area, but if people were in the Americas between 50-80,000 bp. this would correspond with a time in which humans elsewhere in the world had begun to use caves, for shelter and occasionally, burial or caching activities.

After all, it has only been through archaeologists digging down through Clovis horizons that evidence of earlier occupations is coming to light – however, trying to get funding for such adventures on the basis of one brow-ridge and an unidentified fragment of jaw from unstratified and unspecified locations from a lake-side might prove difficult to say the least – but it just might be one of those gambles that produce unexpected and undreamed of payola. Maybe.

Mexico Discovery Fuels Debate About Man's Origins

New Finds In Mexico May Push Back Date For Man's Arrival In The Americas (Excerpted and edited from the "Friends of Calico Newsletter,” October 2004, p. 6.) scroll down to page 6

Tautavel Man

Wikipedia - Abbevillian


Homo erectus In The Americas

Lake Chapala Area Prehistory

image from 'Bones, Boats and Bison' E. James Dixon, (US) (UK) photos by Frederico Solorzano, (used by me for the time being, without permission.)

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