Are the footprints of surprisingly ancient Americans preserved in 40,000-year-old volcanic ash in southern Mexico? In December, an article in the journal Science cast a cloud of doubt over that claim. The authors, Michael Waters and Paul Renne, argue that the ash dated to 1.3 million years ago, much too old for humans on this continent, and that the so-called footprints were nothing more than marks made by the tools of modern workers quarrying the stone with crowbars.
     Now, Silvia Gonzalez, an archaeologist from Liverpool John Moores University, and several members of her research team have published their data and interpretations in the journal Quaternary Science Reviews. Based on their results, the case is far from closed. According to the researchers, the early dates for the ash are wrong. They note that the overlying deposits range in age from 9,000 to 40,000 years, with no evidence of significant breaks in the sequence. Moreover, an article in the March issue of the Mammoth Trumpet states that Gonzalez and her team have dated lake sediments below the ash layer to about 100,000 years ago, which would mean the ash had to be considerably younger than the date reported in Science. Gonzalez and her co-authors also claim the 'footprints' are distinct from recent tool markings, which are sharply defined and unweathered. Also, many of the footprints appear to preserve details of foot anatomy that would not be duplicated by quarry tool divots. Finally, and most importantly, the team has identified more 'potential footprints' in nearby locations "where no quarrying operations have occurred."
     Gonzalez told the Mammoth Trumpet that the only way to fully answer the critics would be "to excavate an area where there has been no quarry activity and uncover more footprints. We will do this as soon as we can." The most famous ancient footprints are the 3.6 million-year-old tracks of early human ancestors excavated by Mary Leakey at Laetoli in Tanzania, Africa. In the current issue of the Journal of Human Evolution, Australian scientists announced the discovery of 23,000-year-old trackways of human footprints in western New South Wales.

Source: Dispatch.com (25 April 2006)