As far back as 22,000 years ago, humans may have improvised makeshift transportation tools that left grooves alongside their own footprints in what is now White Sands National Park in New Mexico.

New research points to the travois — a device usually consisting of two poles joined together to carry a heavy load — as the source of these linear tracks, possibly representing the earliest evidence of transport technology used by humans.

A research team surveyed the tracks in a study recently published in Quaternary Science Advances, reviewing multiple possibilities to discern their origins. The researchers concluded that the tracks were likely carved into the sediment by prehistoric humans who were dragging a travois on the ground to transport items.

Grooves in the Ground

White Sands National Park is home to a high concentration of ancient vertebrate tracks, from marks left by mammoths and ground sloths to some of the oldest human footprints, some of which are also dated to around 22,000 years old. These tracks are scattered across Alkali Flat, a portion of the park where Paleolake Otero — an ice age-era lake that has long since dried up — once existed.

Excavations at Alkali Flat revealed lines traced into sediment, accompanied by adjacent footprints. Across several areas, researchers observed three different types of lines: Type I, featuring deep, narrow grooves that occasionally bifurcate; Type II, featuring broad, shallow runnels that are more straight; and Type III, featuring two lines running parallel to each other. 

Read More: Did Researchers Find 21,000-Year-Old Human Footprints in New Mexico?

Investigating the Tracks’ Origins

In the study, the researchers assessed the viability of other potential explanations for the lines, including non-human animals, flotsam, the keel of ancient boats, and firewood.

Animal tracks are common at Alkali Flat, which is also known as the “mammoth trample ground” from the prevalence of proboscidean (including mammoth/mastodon) tracks. The features of the lines, though, do not match with marks often made by mammoths dragging their trunks or ground sloths dragging their tails on the ground. 

Flotsam — trunks and branches that would have washed ashore from Paelolake Otero — is not a fitting explanation either, according to the researchers, as the Alkali Flat lines are always above, and not within, lake sediment. 

The researchers acknowledged the possibility that the lines could have been created by a keel (an extended structural component that runs below a boat). However, some of the boats they considered wouldn’t have had a pronounced keel to create grooves in the ground, including boats made from reed or tule (a wetland sedge plant) and bull boats covered with buffalo hide. Others simply wouldn’t have been present in the Great Plains or Southwest regions of the U.S., like bark canoes or baidarka (originating from the Aleutian Islands of Alaska).

Lastly, while firewood dragging on the ground could fit the Type I lines, they could not have created the broader Type II lines, the researchers state. As for the Type III lines, a log with two branches or stubs could have theoretically dug parallel lines, but the researchers note that they would have then expected to see cases featuring more than just two lines (denoting firewood with multiple branches), which have never been observed at Alkali Flat.

Prehistoric Use of the Travois

The most likely explanation of the lines is that humans used a travois to haul loads, which has been recorded in historical documents and accounts of Indigenous traditions, particularly in the Great Plains region. These devices were commonly pulled by dogs or horses, but in the case of Alkali Flat, researchers believe a human-drawn travois made the lines.

To confirm this, they replicated transportation with hand-pulled travois devices in a series of tests on mud flats in Dorset, U.K., and Maine. The results led to traces that were similar to the Alkali Flat tracks, with the poles dragged in the mud, truncating footprints.

The footprints alongside the Alkali Flat tracks were also of various sizes; the presence of smaller footprints signifies that children may have joined an adult who was pulling a travois. If the tracks and footprints truly were made 22,000 years ago, as dating methods suggest, this would predate the earliest recorded instance of a vehicle with wheels, believed to have been invented around 5,000 years ago in the Middle East.

The use of the travois, especially at Alkali Flat, could reflect the advent of transportation technology long before wheels existed. The prehistoric people who relied on them, perhaps to move camp or carry meat from a hunting site, created a simple yet effective tool that would go on to become a crucial aspect of life for American Indigenous tribes several millennia later.

Read More: Pebbles Push Back the Invention of the Wheel to About 12,000 Years Ago

Article Sources

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Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.