Techniques for verifying human footprints: reappraisal of pre-Clovis footprints in Central Mexico

Verification of human footprints within the geological record provides critical evidence of presence as well as information on the biomechanics of the individuals who made those prints. Consequently, the correct identification of human footprints is important, but is something for which critical and objective criteria do not exist. The current paper attempts to address this issue by presenting a new statistically based approach to the verification of human footprints. The importance of this is illustrated by the recent controversy surrounding a series of marks identified as human prints in the Valsequillo Basin in Central Mexico dated originally to 40 000 years ago. The dating of these marks remains highly controversial with some teams placing their age at 1.3 million years old. Irrespective of this debate the crucial question that must be addressed is whether or not they represent evidence of human presence. Using an objective statistically based methodology developed here, these controversial marks are re-examined and found to be of questionable origin, as they are inconsistent with a suite of other, known human and hominin prints. Consequently, we argue that they should be removed as evidence in the ongoing controversy surrounding the colonization of the Americas.