Walking in mud: Remarkable Pleistocene human trackways from White Sands National Park (New Mexico)

Abstract

Human tracks at White Sands National Park record more than one and a half kilometres of an out-andback journey and form the longest Late Pleistocene-age double human trackway in the world. An adolescent or small adult female made two trips separated by at least several hours, carrying a young child in at least one direction. Despite giant ground sloth and Columbian Mammoth transecting them between the outbound and return journeys, the human tracks show no changes indicative of predator/prey awareness. In contrast, the giant ground sloth tracks show behaviour consistent with human predator awareness, while mammoth tracks show no such apparent concern. The human footprints are morphologically variable and exhibit left-right asymmetry, which might be due to child carrying. We explore this morphological variability using methods based on the analysis of objective track outlines, which add to the analytical toolkit available for use at other human footprint sites. The sheer number of tracks and their remarkable morphological variability have implications for the reliability of inferences made using much smaller samples as are more common at typical footprint sites. One conclusion is that the number of footprints required to make reliable biometric inferences is larger than often assumed. Highlights We describe a long prehistoric human trackway (1.5 km) of Late Pleistocene age at White Sands National Park (New Mexico, USA).  The double trackway consists of two parallel journeys. The outward journey is crosscut by the tracks of giant ground sloth and Columbian Mammoth. The return journey crosscuts these animal tracks.  Morphological variability is explored using track outlines.  This variability suggests that minimum sample sizes for biometric inferences are larger than commonly assumed.

When is enough, enough? Questions of sampling in vertebrate ichnology

“…Two trackways, possibly the longest in the world (Bennett et al . 2020), from White Sands National Park show significantly more variance than the other trackways. The track‐maker moved over a flat surface with a uniform substrate at a steady speed.…”

“…A, bootstrapped sample of track length for the White Sands National Monument (WHSA) double trackway (Bennett et al . 2020); as the sample size increases the variance falls. B, variation in standard error (SE) with sample size for the WHSA double trackway; note the wide variance within the 95% confidence area.…”

Hunter-gatherer children in the past: An archaeological review

“…These footprints clearly show children participating in foraging trips with women and older children between 7,920 and 6,600 years 14 C BP (Bayón et al 2011). In New Mexico, a single woman or young adult man left a trackway of footprints 1.5 kilometres long directly across a mudflat (Bennett et al 2020). Periodically, this person set down a child under the age of two, but largely they carried the child while moving swiftly and purposefully.…”

“…In addition, the presence of children's footprints at open-air sites, while less common, is documented at Monte Hermoso 1, along Argentina's Atlantic coast (Bayón and Politis 1996;Bayón et al 2011), and in White Sands National Park, New Mexico, USA (Bennett et al 2020). At Monte Hermoso 1, hunter-gatherer children, youths and women left hundreds of footprints along the shore of a pond, likely while gathering plants and bird eggs.…”

“…In the meantime, a giant sloth and a mammoth had crossed the person's first trackway, indicating that these tracks are at least 10,000 years old. While the purpose of this traveller is unclear, it appears that an important component of their journey was the swift, efficient transport of the child (Bennett et al 2020).…”