- Archaeologists unearthed the longest path of fossilized footprints ever found.
- People around the world laid now-fossilized footprints during daily walks.
- These prints are so numerous that they open up entire new areas of investigation for researchers.
Researchers studying fossilized footprints in New Mexico say they have the longest-preserved single path ever found. With 400 identified steps over almost a mile, the scientists have enough information to study the journey and put it in context.
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A young person carrying a toddler on one hip made a walk in one direction, they say, then doubled back without the small child. The daily daycare dropoff has never before been studied so closely.
In their new paper, researchers explain the full extent of their wealth of both human and animal tracks at New Mexico’s White Sands National Park:
“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.”
But the animals were aware of the humans, they say, or at least the sloth was: “In contrast, the giant ground sloth tracks show behaviour consistent with human predator awareness, while mammoth tracks show no such apparent concern.”
In the paper, the scientists use pressure maps—like topological geographical maps, but for the depth of each footprint. Based on how the foot strikes and sinks into the muddy ground that turned to rock, the scientists can begin to draw conclusions. This is how they know, for example, that the young person was carrying a child on one side. One side’s prints were heavier, and there was even a place where the child was briefly set down.
They also say the young person carried the child for “at least” one trip. This makes sense, too—in several hours, the mud could have changed enough that the same combined weight of young adult and child didn’t sink as much, for example. And the trip could have been to retrieve whatever prehistoric Baby Bjorn could help the young adult carry the child more easily, maybe on their way to spend time gathering food or some other hands-requiring activity.
The scientists can tell the two sets of human prints were separated by some time as part of the high variability in the entire set of footprint samples, they say. In fact, the extraordinary number of footprints has a meta-lesson for all biometric study of surviving fossilized footprints. “One conclusion is that the number of footprints required to make reliable biometric inferences is greater than often assumed,” they explain.
That’s a tough lesson, because finding a giant amount of these footprints is vanishingly rare. The implication is that very few of the world’s footprinted sites are able to be reasonably analyzed for biometrics—qualities like someone’s height or body weight that could be extrapolated with enough information. These insights can be really valuable, but only if they’re scientifically sound.
The takeaway makes sense, though. Think about walking around in your yard and picking up the leaves you find, then compare that to what someone would find in your entire neighborhood, let alone your entire city or region. A large-enough sample size is vital to understanding how “good” scientific models can be.
Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.