Of very ancient footprints in Puebla (Mexico).

[Jacques Cinq-Mars]

All,

Here are two very similar versions of an interesting story that is presently making the media round.

Ancient 'footprints' found in Mexico

Rex Dalton
news@nature.com
Published online: 4 July 2005

Find may push back dates of when people arrived in the Americas.

Researchers think they may have found footprints in southern Mexico that mark the oldest evidence for the presence of humans in the Americas.

The impressions, preserved in volcanic ash outside the city of Puebla, have been dated to about 40,000 years ago, beating the oldest accepted evidence of humans in the Americas by some 25,000 years. If proven, the prints would lend support to controversial theories that people reached this land much earlier than previously thought.

The researchers themselves say more work needs to be done to confirm that they have found the mark of human steps. "I believe they are footprints," says geoarchaeologist Silvia Gonzalez of Liverpool John Moores University, UK, who is originally from Mexico. "But we are being cautious, as we need to do more work."

Gonzalez reported the discovery on 4 July at the Royal Society's Summer Science Exhibition in London.

Long-distant runners

The team first stumbled on the prints in the summer of 2003 while hiking between archaeological sites near the dried bed of Valsequillo Lake. They found an ash field peppered with more than 200 impressions that seem to be footprints from several people, including children, along with birds, cats, dogs and species with cloven feet. Gonzalez thinks they might have been fleeing an eruption from the nearby Cerro Toluquilla volcano.

The prints are plainly exposed and in an area that sees traffic in everything from miners who quarry the ash to recreational cyclists. Some worry that human interference, along with heavy rains, might have acted to make the impressions that now look like footprints.

Thomas Higham of the University of Oxford, UK, used radiocarbon dating on shells in sediments just above the layer of ash and found they were about 40,000 years old.

Early arrival

The prevailing theory is that people first migrated from northern Asia between 15,000 and 10,000 years ago, crossing to America over a land bridge at the Bering Strait. But controversial genetic analyses of Native American populations indicate that some immigrants may have arrived much earlier than that, up to 40,000 years ago. That predates the ice age that held much of North America in its grip some 20,000 years ago.

No direct evidence has been found for this early arrival. The oldest archaeological evidence is found in Chile's Monte Verde ruins, which contains signs of campfires and other clues of human occupation from about 14,500 years ago.

Debate continues about what the marks really represent. "I've seen them up close and personal, and I don't think they are footprints," says Paul Renne, a geochronologist at the University of California, Berkeley. Renne is keen for the team to find further evidence of human occupation that might shore up its claim.

Bruce Latimer, a human anatomist at the Cleveland Museum of Natural History in Ohio who helped identify some 3.5-million-year-old Laetoli footprints in Tanzania, agrees that caution is necessary. He says that human prints are usually so distinctive they are hard to miss. "I have not seen them. But if you have to equivocate, it is probably not human."

The team plans to excavate the site in the Valsequillo Lake basin early next year, in an attempt to uncover other footprints or signs of human life. Late last month, the British Natural Environment Research Council gave the Gonzalez team a US$370,000 grant to continue their work.

Click HERE for access to the original article.

Footprints of 'first Americans'

By Paul Rincon

BBC News science reporter
BBC News, Tuesday, 5 July, 2005

People left traces of their presence in the sediments of a shoreline
Human settlers made it to the Americas 30,000 years earlier than previously thought, according to new evidence.

British scientists came to this controversial conclusion by dating human footprints preserved by volcanic ash in an abandoned quarry in Mexico.

They say the first Americans may have arrived by sea, rather than by foot.

The currently accepted theory is that the continent's early inhabitants arrived 12,500 years ago, by crossing a land bridge between Siberia and Alaska.

Details of the latest findings were unveiled at the UK Royal Society's Summer Science Exhibition.

Ancient lake

Scientist Silvia Gonzalez of Liverpool's John Moores University and her colleagues found the footprints in the quarry, some 130km (80 miles) south-east of Mexico City, in 2003. But they have only finished dating them this year.

"The footprints were preserved as trace fossils in volcanic ash along what was the shoreline of an ancient volcanic lake," Dr Gonzalez said.

Their footprints were soon covered in more ash and lake sediments and, when water levels rose, became as solid as concrete.

Dr Gonzalez was under no illusions that the finding would be controversial: "It's going to be an archaeological bomb," she told the BBC News website, "and we're up for a fight."

The team used several methods to date a variety of material from the site near Puebla, Mexico, in order to be sure they were right about the age.

"We have materials that have been dated below the footprint layer, the footprint layer itself and on top of the footprint layer. Everything is making sense," said Dr Gonzalez.

The researchers used radiocarbon dating on shells and animal bones in the sequences and dated mammoth teeth by a technique called electron spin resonance. The sediments themselves were dated by optically stimulated luminescence.

"Some lake sediments were incorporated into the ash and were baked. They look like small fragments of brick and these were the ones we dated in the footprint layer. They gave us a result of 38,000 years," Dr Gonzalez.

Land crossing

Under the traditional view of how the Americas were settled, humans trekked from Siberia to Alaska across a land bridge that linked these land masses at the end of the last ice age (between 10,000 and 12,500 years ago).

Central to this theory, called the Clovis First model, are Clovis points - the tools these settlers used to hunt large beasts, or megafauna, such as mammoths and mastodonts.

"The existence of 40,000-year-old human footprints in Mexico means that the Clovis First model of human occupation can no longer be accepted as the first evidence of human presence in the Americas," said co-investigator David Huddart, of Liverpool John Moores.

Dr Michael Faught, an expert in early American archaeology, said the findings sounded interesting: "It would be significant if it were demonstrated, but usually those (early) sites don't hold up well," he told the BBC News website.

But, he added: "There's more and more evidence that Alaska was not the only place people came into the continent."

Dr Gonzalez is a proponent of the Coastal Migration Theory. This proposes that people arrived in boats, hugging the coastline from North to South.

But where these settlers came from is still a mystery, she says. Some have proposed that the earliest humans to reach the continent could have come from south-east Asia or even Australia.

Genetic studies of present-day Native American populations support a recent arrival from north-east Asia, which agrees well with an entry through the Beringian land bridge at the end of the last Ice Age.

Dr Gonzalez suggests that the earliest settlers may have become extinct and therefore left no genetic legacy in modern populations. She thinks these hunters may have been highly mobile, living in small groups, perhaps explaining why they left scant trace of their presence.

Dr Gonzalez and ancient DNA expert Alan Cooper, of the University of Adelaide in Australia, have managed to extract genetic material from three molars belonging to Peñon Woman III, a 13,000-year-old partial skeleton from Mexico. The work and analysis is still underway.

Click HERE for access to the original article.

Jacques Cinq-Mars

[Mikey Brass]

Dr Silvia Gonzalez
http://cwis.livjm.ac.uk/bie/Research/Research_Staff/Bio_Anth/Gonzalez.htm

There is a picture of the print at http://cwis.livjm.ac.uk/

I fail to see the ball of the foot conclusively, the "arch" is not properly shaped, ant the "toes" are not persuasive either.

I agree with C. Andrew Hemmings' post on ARCH-L where he states:

"If you go to the main page of the Liverpool University she teaches at there is a different view of the "footprint" from what would be the left lateral side looking medially towards the "arch"-  Well, the arch of the print is simply the portion of the sediment that they did not excavate.  The picture the BBC has and is used in the two popular articles I've seen.
"The anatomical struct is all wrong as well- the thickest part of the arch is on the lateral edge- that can't be.  Also- when viewed closely you can see that the "toes" are not prints at all but terraced excavations.  This is not even a natural formation of anything- it must have looked like something when they dug it out and proceded to "dig out a foot" if you will.   I have no axe to grind about this stupidity- Go look for yourself and decide........"

In addition, (from another news report)
> Thomas Higham of the University of Oxford, UK, used radiocarbon
> dating on shells in sediments just above the layer of ash and
> found they were about 40,000 years old.

14C on shells is not very reliable, and 40kya is hitting the infinite barrier. This raises very serious questions over contamination and the suitability of the sample or samples dated.

[Daryl Habel]

In view of the publicity this announcement has generated, and with no currently available reviewed publication, the most reliable information probably can be found in 'mining' the webpages of the Liverpool John Moores University at:

CLICK HERE

In particular,  make sure to visit the link titled "Newsroom".

CLICK HERE FOR 'NEWSROOM'

On the left-hand side of the "Newsroom" page there are icons for downloading both Spanish and English language versions of the original press release in pdf files.  I've only read the English version:
CLICK HERE FOR PDF,
but this is much more informative and probably more accurate than any of the news media stories I've yet encountered.  In particular, for information dealing with the dating of the footprints.  In addition, there is an icon for the "Image Library"
CLICK HERE,
which, in addition to 'higher resolution images" (photographs), has a contour diagram of one of the 'human' prints' (as well as the same for cloven-hoofed prints), and a number of maps, charts (including chart with dating information), etc., which can provide additional insights on this discovery although, unfortunately, these images are not captioned.

Dar

[Jacques Cinq-Mars]

In view of the publicity this announcement has generated, and with no currently available reviewed publication, the most reliable information probably can be found in 'mining' the webpages of the Liverpool John Moores University at:
<snip>

Dar

Dar,

Thanks for passing this on. Having a good look at this material should cause some of our more excitable friends and colleagues to stand back a bit and refrain, for a while, anyway, from unwarranted, uncalled for media driven speculations regarding the true nature of these finds and the personalities of the researchers involved.

From my point-of-view, I can tell you -- and this should not surprise you -- that when viewed through the larger prism provided by the growing number of other perfectly valid "pre-Clovis" sites from both North and South America, this particular set of finds sounds perfectly reasonable. As you mentioned elsewhere, now is time to sit tight [my words] and wait for the actual publications.

Jacques

[Jacques Cinq-Mars]

Dr Silvia Gonzalez
http://cwis.livjm.ac.uk/bie/Research/Research_Staff/Bio_Anth/Gonzalez.htm

There is a picture of the print at http://cwis.livjm.ac.uk/

I fail to see the ball of the foot conclusively, the "arch" is not properly shaped, ant the "toes" are not persuasive either.

I agree with C. Andrew Hemmings' post on ARCH-L where he states:

"If you go to the main page of the Liverpool University she teaches at there is a different view of the "footprint" from what would be the left lateral side looking medially towards the "arch"-  Well, the arch of the print is simply the portion of the sediment that they did not excavate.  The picture the BBC has and is used in the two popular articles I've seen.
"The anatomical struct is all wrong as well- the thickest part of the arch is on the lateral edge- that can't be.  Also- when viewed closely you can see that the "toes" are not prints at all but terraced excavations.  This is not even a natural formation of anything- it must have looked like something when they dug it out and proceded to "dig out a foot" if you will.   I have no axe to grind about this stupidity- Go look for yourself and decide........"

In addition, (from another news report)
> Thomas Higham of the University of Oxford, UK, used radiocarbon
> dating on shells in sediments just above the layer of ash and
> found they were about 40,000 years old.

14C on shells is not very reliable, and 40kya is hitting the infinite barrier. This raises very serious questions over contamination and the suitability of the sample or samples dated.

Mikey,

Just a few points, here.

First you should tell this Mr. Andrew Hemmings about the PALANTH Forum and particularly about what Dar has just brought up.

Second, you should have a look at what comes out of Google when one does a search using, for example "radiocarbon dating of shells”, i.e., an amazing quantity of up-to-date information indicating that some progress has been made in the 14C dating (AMS, by the way) of shells.

Third, I don't think that your qualms about "40kya [...] hitting the infinite barrier" are warranted in the present context, and this, for a number of reasons:

- advances in radiocarbon dating, involving both the nature/integrity of samples and the use of an increasingly refined AMS technology, now allow -- given the right circumstances -- can now allow to target ages well into the range you are talking about; in contrast, I remember the days when most dates above 30k were viewed by many as iffy, i.e., “infinite”;

- from reading the material that has been made available so far, it apprears that the 40k age estimate is the result of a combination of dating techniques, not just 14C-AMS on shells; and, finally,

- if confirmed, these finds will be a welcome addition to the growing body of data that can (should) be used to demonstrate that human dispersals in the New World do predate the Pleistocene/Holocene boundary, and the LGM.

Jacques

[Mikey Brass]

Second, you should have a look at what comes out of Google when one does a search using, for example "radiocarbon dating of shells”, i.e., an amazing quantity of up-to-date information indicating that some progress has been made in the 14C dating (AMS, by the way) of shells.

As I understand it from the reports, it was standard 14C dating and not AMS. I was, originally, stating that AMS should have been used.

- from reading the material that has been made available so far, it apprears that the 40k age estimate is the result of a combination of dating techniques, not just 14C-AMS on shells;

I saw that after I had already made the posts. It would be nice if true, however I would rather wait to read the publication report.

[Jacques Cinq-Mars]

As I understand it from the reports, it was standard 14C dating and not AMS. I was, originally, stating that AMS should have been used.

I'll come up, soon, I hope, with a few additional comments on this, in the Archaeometry & Chronostratigraphy Board

I saw that after I had already made the posts. It would be nice if true, however I would rather wait to read the publication report.

We agree on this, but I'll just point out that the present lack of a properly published scientific report, has certainly not prevented the rapid development, on many venues -- other than the Forum, I am glad to say -- of the usual, media driven "feeding frenzy" that, at times, verged on the irrational.

Jacques

[SteveF]

Tom Higham at Oxford uses AMS dating.  Actually, using AMS vs. traditional C14 dating isn't particularly about accuracy, rather its more a question of precision (the two things are very different). 

Also, dating of marine shells isn't too much of a problem nowadays - the actual date given won't be especially accurate as we don't have a decent reservoir correction that far back (not withstanding issues of calibration etc), but assuming there is no contamination then the fact that it is shell being dated isn't a major problem.

In addition, other dating techniques were used (though obviously more details are required):

http://www.mexicanfootprints.co.uk/research/datefoot.htm

My personal take is that the dating will probably be fine.  I'll leave the footprints to those experienced in such matters.

[shenzhou]

according to the latest issue of nature:

Geochronology: Age of Mexican ash with alleged 'footprints' pE7
Paul R. Renne, Joshua M. Feinberg, Michael R. Waters, Joaquin Arroyo-Cabrales, Patricia Ochoa-Castillo, Mario Perez-Campa and Kim B. Knight
doi:10.1038/nature04425

http://www.nature.com/nature/journal/v438/n7068/abs/nature04425.html

"Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30+-0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash."

[lagarvelho]

Jacques, shenzhou, and all:

Quite frankly, I'm totally puzzled by the whole thing.  On the volcanic rocks/pebbles samples, or whatever they are, I couldn't say any footprints at all.  But then, my eyes aren't as sharp as they once were.
Anne G

[Daryl Habel]

according to the latest issue of nature:

Geochronology: Age of Mexican ash with alleged 'footprints' pE7
Paul R. Renne, Joshua M. Feinberg, Michael R. Waters, Joaquin Arroyo-Cabrales, Patricia Ochoa-Castillo, Mario Perez-Campa and Kim B. Knight
doi:10.1038/nature04425

http://www.nature.com/nature/journal/v438/n7068/abs/nature04425.html

"Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30+-0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash."

Thanks for catching this.  Here, also, is the official press release from Texas A&M:

http://www.eurekalert.org/pub_releases/2005-11/tau-taa113005.php

In the press release it is noted that, so far,  the team headed by Silvia Gonzalez has not published the 'footprints' and the ca. 40 kyr age estimate they announced earlier this year.  If Gonzalez still maintains this position, there will have to be some explanation of this new TL result, especially since it seems to be confirmed with paleomagnetic studies.

Dar

[Daryl Habel]

according to the latest issue of nature:

Geochronology: Age of Mexican ash with alleged 'footprints' pE7
Paul R. Renne, Joshua M. Feinberg, Michael R. Waters, Joaquin Arroyo-Cabrales, Patricia Ochoa-Castillo, Mario Perez-Campa and Kim B. Knight
doi:10.1038/nature04425

http://www.nature.com/nature/journal/v438/n7068/abs/nature04425.html

"Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30+-0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash."

Thanks for catching this.  Here, also, is the official press release from Texas A&M:

http://www.eurekalert.org/pub_releases/2005-11/tau-taa113005.php

In the press release it is noted that, so far,  the team headed by Silvia Gonzalez has not published the 'footprints' and the ca. 40 kyr age estimate they announced earlier this year.  If Gonzalez still maintains this position, there will have to be some explanation of this new TL result, especially since it seems to be confirmed with paleomagnetic studies.

Dar

Silvia Gonzalez has commented on the 1.3 Ma dating reported by Renne et al. in Nature this week on her website. Gonzalez says they will publish their article in the January 2006 issue of Quaternary Science Reviews.  At:
CLICK HERE

And a BBC news report with some interesting quotes from  both sides of the controversy.  Gonzalez says that her team is preparing a response which will be appearing in the journal Nature. At::
CLICK HERE

And an additional news report from Science Daily which has more quotes and information, at:
CLICK HERE

Thanks go out  to Kris Hirst and Mark McConaughy on the archaeology.about.com forum, where I picked up on these.

Dar

[Jacques Cinq-Mars]

All,

Just trying to catch up. -- For the record, here are two institutional releases (via EurekAlert) on a dating exercise whose results, we are told, falsify the claims made earlier by Silvia Gonzalez & al., regarding the occurrence of very ancient footprints near Puebla, along the shores of the Valsequillo reservoir.

Public Release: 30-Nov-2005
Nature
Texas A&M anthropologist studies ancient human footprints
An article published in the prestigious science journal Nature and co-authored by a Texas A&M University researcher places the age of rocks found in Mexico containing possible human footprints at over 1.3 million years. The generally accepted date for the arrival of humans in North America, across a northern land-bridge from Asia, is 11,000 years ago.

Contact: Judith M. White
jwhite@univrel.tamu.edu
979-845-4645
Texas A&M University

Public Release: 30-Nov-2005
Nature
Alleged 40,000-year-old human footprints in Mexico much, much older than thought
When British and Australian researchers announced earlier this year that they'd found human footprints in 40,000-year-old rock near Puebla, Mexico, many anthropologists withheld judgment. And rightfully so. Using both argon/argon and paleomagnetic dating, UC Berkeley geologists have obtained a better date for the volcanic tuff: 1.3 million years. Either the footprints are extremely old, dating from a time before Homo sapiens arose, or they are not footprints at all.

Center for the Study of the First Americans

Contact: Robert Sanders
rsanders@berkeley.edu
510-643-6998
University of California – Berkeley

For additional contacts, click
 HERE

Both releases refer to or summarize the following material just published by Nature:

Nature 438, E7-E8 (1 December 2005) | doi:10.1038/nature04425
Geochronology: Age of Mexican ash with alleged 'footprints'

Paul R. Renne, Joshua M. Feinberg, Michael R. Waters, Joaquin Arroyo-Cabrales, Patricia Ochoa-Castillo, Mario Perez-Campa, and Kim B. Knight.

A report of human footprints preserved in 40,000-year-old volcanic ash near Puebla, Mexico (http://www.royalsoc.ac.uk/exhibit.asp?id=3616&tip=1), was the subject of a press conference that stirred international media attention1. If the claims (http://www.mexicanfootprints.co.uk) of Gonzalez et al. are valid, prevailing theories about the timing of human migration into the Americas would need significant revision. Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30plusminus0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash

Click HERE for the full text.

A story to follow, especially since the word is out that a response from S. Gonzalez & al. should be forthcoming. I am really curious as to what their counter-argument(s) will consist of.

Jacques Cinq-Mars