54. Possible Relatives in the Americas

Toloquilla footprints (Puebla, Mexico)

by George Weber

Location of the alleged Toloquilla footprints found by a joint British-Mexican team.

Red dot: location of footprints Black triangle: location of mini-volcano Cerro Toloquilla

The date of the earliest peopling of the Americas has been controversial ever since the subject has been first broached centuries ago - and is likely to remain so for a long time. The "Clovis First" school of thought in the US until very recently held that the Clovis people dating to not more than 12,000 years or so were the first Americans. Solid evidence is rapidly accumulating that this is not so and that there are traces of older and perhaps much older populations all over North, Middle and South America.

Unfortunately, the rather bitchy controversy surrounding the Toloquilla footprints and their date has done nothing to clarify matters.

The Toloquilla site

The Toloquilla site geology (chart adapted from Gonzalet S. et al. "Human Footprints in Central Mexico older than 40,000 years", Quaternary Science Reviews 25:201-222) (for a link, see end of this article)

The main author and discoverer of the prints, Dr. Silvia Gonzalez (Gonzalez S., et al, 2006. "Human Footprints in Central Mexico older than 40,000 years." Quaternary Science Reviews 25:201-222) writes in her abstract:

The timing, route and origin of the first colonialization of he Americas remains one of the most contentious topics in human evolution. A number ofmigration routes have been suggested and there are different views as to the antiquity of the earliest human occupation. Some believe that settlement happened as early as 30,000 years before present, but most of the currently accepted early sites in North America date to the latest Pleistocene, related to the expansion of the Clovis culture, while the oldest directly radiocarbon-dated human remains are 11,500 years before present. In this context, new evidence is presented in this paper, in the form of human footprints preserved in indurated volcanic ash, to suggest that Central Mexico was inhabited as early as over 40,000 years before present.

Human and animal footprints have been found within the upper nedding surfaces the Xalnene volcanic ash layer that outcrops in the Valsequillo Basin, south of Puebla, Mexico. This ash layer was produced by a subaqueous monogenetic volcano erupting within a palaeo-lake, dammed by lava within the Valsequillo Basin during the Pleistocene. The footprints were formed urng low stands in lake level along the former shorelines and indicate the presence of humans, deer, canids, big felids, and probably camels and bovids. The footprints were buried by ash and lake sediments aslake levels rose and transgressed across the site. The ash has been dated to at least 40,000 before present by OSL-dating of incorporated, baked lake sediments.

So far so good. However, such sensational claims should be supported by rigorously analyzed evidence and extra-proper publication procedures. This has not quite been done here: first the popular media were stirred up, then other scientists studied the geochronology and palaeomagnetics of the site and produced startling dates as far back as 1,300,000 years (i.e. long before Homo sapiens even existed in Africa). Only when the controversy had already reached a considerable noise level did the team of Dr. Gonzalez publish their results. On Dr. Gonzalez's announcement policies on other subjects and the resulting slight credibility problem see also Pericu on this site.

Despite her publicity problems, Dr. Gonzalez's team has made a find that cannot be quite so easily brushed off as was done in an analysis by Renne P.R. and Feinberg J.M. 2005, "Age of Mexican Ash with alleged 'footprints'", Nature, 438:E7-E8, 1 December 2005 (for link see end of this article). Their analysis ends with the dry statement "we conclude that the identification of any of these features as syndepositional hominid footprints is erroneous." In other words, the footprints are not footprints and it is left open what the prints are. Many paleontologists have withheld judgment on the alleged footprints, awaiting good geological data. Renne&Feinberg also seem to have retracted their blunt "erroneous" by saying later that "with this study, we're trying to nip any misrepresentation in the bud." Nipping in the bud is not quite saying "wrong". Oh, these subtle academic bitching rituals!

If the footprints are not footprints, what are they? Don't look at me, I don't know - and the people who know that they are not footprints don't say. They are out, nipping buds.

Other archaeologists who inspected the footprints in situ reported that the impressions were irregular marks that varied in size and depth and that these marks looked similar to those made by workers excavating sheets of hardened volcanic ash. It was even reported that while the archaeologists were at the site, passing quarry workers claimed to have made the marks in question. These labourers do seem to have sense of humour or a lot of spare time at work, perhaps both. In any case, marks made by the quarry workers and their equipment have been distinguished by Gonzalez et all in the original article. While the "workers dig" description would fit some of the "footprints", many others are complete with anatomically correct toes and heels clearly visible and unlikely to be the work of hobby sculptors. There are hundreds of the footprints!

The material in question, called Xalnene Ash by Gonzalet et al, is a tough, somewhat sandy material used as building material today. It is described in Renne and Feinberg's article as as tephra, moderately indurated olivine basalt lapilli tuff. The layers carrying the footprints are dated by them through the 40Ar/39Ar dating method to around 1.3 million years. Gonzalez et al had 40,000 years.

It is the footprints in the volcanic material that need dating separately from the volcanic material in which they occur. The volcanic material may easily be be 40,000 or many millions of years old but this need not say (in this case at least) when the footprints were actually made. Such separate dating may be a very tall, perhaps impossible, order, but it is needed here.

If the footprints were made relatively recently, the ancient rock-hard basalt would need to have gone soft, been powdered or otherwise turned into a mud-like substance at the surface for a time. Is such a thing possible under some circumstances in the peculiar volcanic environment of this site? Could the basalt have been at the bottom of a shallow lake with its top layer dissolved by some volcanic chemicals and water before people and animals waded through it? I am not saying, I am asking. Unlikely it may be, but perhaps slighly less unlikely than people and animals with anatomically modern feet walking around in Mexico more than one million years ago (Gonzalez), or human and animal footprint-like forms inexplicably appearing in basalt out of nowhere (Renne and Feinberg).

If I may be allowed here to coin an totally new, never before used and highly original phrase: only more research will answer this question.

Some of the footprints found at the Toloquilla site do look rather like genuine footprints...

... while others look rather less convincing.

The same "footprints" as above right - but showing a long sequence of "prints".

Overview maps of Toloquilla footprint sites A, B and C (charts adapted from Gonzalet S. et al. "Human Footprints in Central Mexico older than 40,000 years", Quaternary Science Reviews 25:201-222).

Among web-sites with further information are:

- http://www.admin.ox.ac.uk/po/news/2004-05/jul/12a.shtml

- http://www.mexicanfootprints.co.uk/

- http://www.livescience.com/humanbiology/051130_ancient_footprints.html

- http://www.theeagle.com/stories/120105/am_20051201041.php

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Last change 1 January 2007