July 5, 2005

Be Cautious about the 40,000-Year-Old "Footprints" for Mexico

News@Nature.com reported yesterday that Silvia Gonzalez, who was born in Mexico but is now in England, has discovered impressions preserved in volcanic ash that may be footprints of a person. Gonzalez led a team consisting of David Huddart of Liverpool John Moores University and Matthew Bennett of Bournemouth University. The actual discovery was made in 2003. These multiple impressions were discovered in southern Mexico. Here's the exciting part. The ash in which they are impressed is 40,000 years old! Much older than the oldest proposed date (~25,000 BP) for the first humans in the Americas. It is, therefore, far older than the more common date of 11,000 BP.

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."

There are about 200 separate impressions that have the general appearance of one or, to my eye, perhaps two persons walking in a more or less straight path. Gonzalez speculates that, if they are indeed human footprints, the people may have been fleeing an eruption of nearby Cerro Toluquilla volcano.

But just as the discoverers are cautious, so the rest of us should be cautious.

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.
"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."

You can find a good picture of the impressions on the Nature website and at the New Science website. There are several other places that have commented on this find with the same degree of caution.

There is even an official website for the "Footprints" that also has some good pictures but it does not seem to be as cautions as one might hope.

Posted by Duane Smith at July 5, 2005 3:27 PM | Read more on Paleoanthropology |

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“if an amazing new discovery is found I probably will have nothing to say about it” I’m used to being proved wrong, but it would be nice to get through 24 hours before it happens. After posting this on July 5, I flicked across to the BBC news sit... [Read More]

Tracked on July 6, 2005 3:31 AM