Posted on 11/30/2005 11:24:19 AM PST by blam
Contact: Robert Sanders
rsanders@berkeley.edu
510-643-6998
University of California - Berkeley
Alleged 40,000-year-old human footprints in Mexico much, much older than thought
Berkeley -- Alleged footprints of early Americans found in volcanic rock in Mexico are either extremely old - more than 1 million years older than other evidence of human presence in the Western Hemisphere - or not footprints at all, according to a new analysis published this week in Nature.
The study was conducted by geologists at the Berkeley Geochronology Center and the University of California, Berkeley, as part of an investigative team of geologists and anthropologists from the United States and Mexico.
Earlier this year, researchers in England touted these "footprints" as definitive proof that humans were in the Americas much earlier than 11,000 years ago, which is the accepted date for the arrival of humans across a northern land-bridge from Asia.
These scientists, led by geologist Silvia Gonzalez of Liverpool's John Moores University, dated the volcanic rock at 40,000 years old. They hypothesized that early hunters walked across ash freshly deposited near a lake by volcanoes that are still active in the area around Puebla, Mexico. The so-called footprints, subsequently covered by more ash and inundated by lake waters, eventually turned to rock.
But Paul Renne, director of the Berkeley Geochronology Center and an adjunct professor of earth and planetary science at UC Berkeley, and his colleagues in Mexico and at Texas A&M University report in the Dec. 1 issue of Nature a new age for the rock: about 1.3 million years.
"You're really only left with two possibilities," Renne said. "One is that they are really old hominids - shockingly old - or they're not footprints."
Renne's colleagues are Michael R. Waters, director of the Center for the Study of the First Americans at Texas A&M University; Joaquin Arroyo-Cabrales and Mario Perez-Campa of the Mexican National Institute of Anthropology and History; Patricia Ochoa Castillo of the Mexican National Museum of Anthropology; and UC Berkeley graduate students Joshua M. Feinberg and Kim B. Knight. The Berkeley Geochronology Center, located a block from the UC Berkeley campus, is one of the world's preeminent anthropological dating laboratories.
Paleoanthropologist Tim White, professor of integrative biology at UC Berkeley, is familiar with the "so-called footprints" and knows Renne well, frequently collaborating with him in the dating of million-year-old sediments in an area of Ethiopia where White has excavated numerous fossils of human ancestors. He is not surprised at the new finding.
"The evidence (the British team) has provided in their arguments that these are footprints is not sufficient to convince me they are footprints," said White, who did not contribute to the new work that Renne's group is reporting in Nature. "The evidence Paul has produced by dating basically means that this argument is over, unless indisputable footprints can be found sealed within the ash."
Renne determined the new date using the argon/argon dating technique, which reliably dates rock as young as 2,000 years or as old as 4 billion years. The British-led researchers, however, relied mainly on carbon-14 dates of overlying sediments. Carbon-14 cannot reliably date materials older than about 50,000 years.
The idea for another test that, it turns out, throws more cold water on the footprint hypothesis came to Renne one morning in the shower. Many rocks retain evidence of their orientation at the moment they cool in the form of iron oxide grains magnetized in a direction parallel to the Earth's magnetic field at the time of cooling. Because the Earth's field has repeatedly flipped throughout the planet's history, it is possible to date rock based on its magnetic polarity.
Feinberg found that the rock grains in the volcanic ash had polarity opposite to the Earth's polarity today. Since the last magnetic pole reversal was 790,000 years ago, the rock must be at least that age. Because the Earth's magnetic polarity changes, on average, every 250,000 years, the argon/argon date is consistent with a time between 1.07 and 1.77 million years ago when the Earth's polarity was opposite to that of today.
Moreover, Feinberg found that each individual grain in the rock is magnetized in the same direction, meaning that the rock has not been broken up and reformed since it was deposited. This makes extremely unlikely the possibility that the original ash had been weathered into sand that early humans walked through before the sand was welded into rock again.
"Imagine two-millimeter-wide BBs cemented together where they're touching," Feinberg said. "The paleomagnetic data tell us that these things did not move around at all since they were deposited. They haven't been eroded and redeposited anywhere else. They fell while they were still hot, which raises the question of the validity of the footprints. If they were hot, why would anybody be walking on them?"
The British researchers, funded by the United Kingdom's Natural Environment Research Council, have promoted their hypothesis widely, most prominently at a July 4, 2005, presentation and press conference at the Royal Society's Summer Science Exhibition 2005 in London. The team, which includes Gonzalez as well as Professor David Huddart from John Moores University, also involves scientists from Bournemouth University, the University of Oxford and the Australian National University. They have yet to publish a peer-reviewed analysis of the footprints.
In all, the British team claims to have found 250 footprints - mostly human, but also dog, cat and cloven-hoofed animal prints - in a layer of volcanic ash deposited in a former lake bed now exposed near a reservoir outside Puebla. Its dating techniques returned a date of 40,000 years ago, in contrast to the oldest accepted human fossil from the Americas, an 11,500-year-old skull. This makes the rock "one of the most important areas in the study of early human occupation in the Americas and would support a much earlier human migration than is currently accepted," the team wrote.
One of the team members, Matthew Bennett of Bournemouth, was quoted on a Royal Society Web site as saying, "Accounting for the origin of these footprints would require a complete rethink on the timing, route and origin of the first colonization of the Americas."
Renne, Knight, Waters and the Mexico City archeologists visited the site at the Toluquilla quarry last year while collecting rocks from another anthropological site across the reservoir. Renne noted that the black, basaltic rock is very tough and is mined in slabs for building. Pre-Columbian Mexicans also constructed buildings from the rock, which they called xalnene, meaning "fine sand" in the Nahuatl language. Today, trucks headed toward the quarry routinely drive across the xalnene tuff in which the alleged footprints are found, and the rock itself is pockmarked with many depressions in addition to the alleged footprints.
"They're scattered all over, with no more than two or three in a straight line," which would be expected if someone had walked through the ash, Renne said. If the depressions were footprints, they could not have been made by modern humans, he noted, since even in Africa, Homo sapiens did not appear until about 160,000 years ago. Given the age of the volcanic rock and lacking other evidence of early human ancestors in the Americas 1.3 million years ago, the researchers wrote in their paper, "we consider such a possibility to be extremely remote."
Many paleontologists have withheld judgment on the alleged footprints, awaiting good geological dates, Feinberg said. "With this study, we're trying to nip any misrepresentation in the bud."
### The research was supported by the Center for the Study of the First Americans, the North Star Archaeological Research Program and the Berkeley Geochronology Center.
It appeared in the news this year, maybe 6 months ago. I'll try to dig it up but it was based upon some oceanographers work that failed to find evidence that the sea level as ever low enough to expose the sea floor in that part of the Bering sea. Seemed pretty mainstream to me, I don't generally read the fringe stuff.
"Mexico ancient footprints" brings up a few weird photos! :-)
I found the source for those photos you posted. If I read this page en espanol correctamente, those are in Managua, Nicaragua.
Ping me too. I've not seen anything about this either.
Please ping me to. Thanks.
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:') It would mean that the most recent flip was 40,000 years ago. But as someone else pointed out, that's average. It's also not much good for dating except for ballparking, because other methods have to be used to determine the age of the deposit.
They were gellin'.
" Where do you buy your cosmoline? Since my local Army-Navy Store went out of business I haven't seen any."
Vaseline is just about the same, just slightly more refined.
Wow...... have to remember to read the article and posts later and maybe to a little Googling.
Wow - footprints of a 40,000 year old human? I hope I'm able to walk when I get that old!
Millions of years, now isn't that interesting.
Amazing, huh?
I'm anxious to hear your theory that explains this.
?????? not sure what you mean.
If you are talking about God and creation, I have never believed that God's idea of time and ours coincide. There has to be an explanation for the fossil remains of the dinosaurs etc.. Which is why although I am a Christian and believe in creation I do not find it logical to say the earth is 6,000 years old.
I was young when I decided about the time frame. It is logical and having done accounting all my working life I had to find logic. So what works for me is, God's time is more likely a million years to one of our hours or a billion or more years to one of our days.
Is this what you meant about my 'theory'? It is as good as or better than many I have heard.
Mainly I was just 'funning' with you.
I haven't a theory at all good or bad...which is rare for me, lol.
I do know that Africa and S America began splitting apart 120 million years ago, so...they either developed here, took a boat or walked around through Berlinga.
I'm expecting the dates to be proven wrong.
Exactly....Epluribus_2 has the right idea probably, in that one or both testing methods (Ar-Ar or C-14) may be flawed. It's odd how Renne didn't mention that possibility.
I do know that Africa and S America began splitting apart 120 million years ago, so...they either developed here, took a boat or walked around through Berlinga.
I'm expecting the dates to be proven wrong.
Yes, I am sure they will be updating the information on the dates. They always do.
It would be great if we did not have so much 'theory' and more provable facts.
I love this stuff.
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Indigenous ArchaeologyI've gotten through several of the papers in response to McGhee's original paper on Indigenous Archaeology (IA). I'm afraid they are not pursuading me of any essential incorrectness of McGhee's central argument, though I think there is some talking past each other going on. Few address what I think is McGhee's central thesis, whether IA is contributing or has the potential to contribute to archaeological explanation. Lots of assertions are made about how Indigenous peoples can provide special "insight" or "perspectives" on archaeological remains, but that strikes me as largely polemical. What insight and is it in any way supportable? Croes has been the most specific so far, giving a few actual examples, but these are pretty unimpressive in my view. Largely it revolves around tribal "elders" (did you know that a contemporary tribal "elder" would have grown up in the 1950s? How does that relate to having expertise in explaining something from 2,000 years ago?) providing "detailed knowledge" of certain artifacts or features. Stating that only begs the question of whether this "knowledge" is in any way accurate or demonstrable. He mentions one instance where they tested some interpretations of shanked fishooks experimentally, but that is neither a new idea nor sufficient to establish anything beyond plausibility. He also goes into some basketry traditions that may have some elements of design spanning thousands of years and miles, but that's really not an IA question either, but a longstanding archaeological problem.
Dr. Anthony Cagle
Tuesday, May 18, 2010
Old topic, from the FRchives. Adding to the list, not pinging.
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