Researchers working near the shore of a dried-up lake basin in southeastern Australia have taken a giant leap backward in time. They’ve uncovered the largest known collection of Stone Age human footprints.
The 124-or-more human-foot impressions, as well as a few prints left by kangaroos and other animals, originated between 23,000 and 19,000 years ago in a then-muddy layer of silt and clay, say archaeologist Steve Webb of Australia’s Bond University in Robina and his colleagues. Their report appears in the January Journal of Human Evolution.
The discoveries, which lie in an area consisting of 19 ancient lake basins known as the Willandra Lakes system, provide a unique look at the behavior and physical capabilities of late Stone Age people, notes geologist and study coauthor Matthew L. Cupper of the University of Melbourne.
An aboriginal woman found the footprints in August 2003 while assisting Webb in an archaeological survey of the area. Webb and his coworkers determined that erosion had exposed 89 footprints. The researchers then dug through soil to find another 35 footprints.
To estimate age, the team shone a laser light on sand grains from sediment just above and below the footprint-bearing soil layer. Light emitted in response provided a measure of accumulated radioactivity, from which the group calculated the sediments’ ages.
Intriguingly, 76 footprints belong to the tracks of eight individuals of different sizes and ages. The foot sizes and stride lengths, in comparison with those of modern aborigines, indicate that six relatively large adults ran in the same direction across the muddy plain. Two of them exceeded 6 feet in height. Another two people, a teenager and a child, walked in the same general direction.
“It’s possible that these people were venturing between the shores of the two nearest large lakes,” Cupper says. “Maybe they were moving from one temporary camp to another, or perhaps they were on a hunting or fishing expedition.”
Whatever these Stone Age folk were doing, the largest of them achieved a running speed of perhaps 12 miles per hour, comparable to that of a fit recreational runner today, Cupper says. The researchers made that calculation by comparing the stride lengths of the prehistoric adult with comparable data from modern distance runners of similar height.
Circular indentations, no more than 2 inches across, appear irregularly in the soil near the human footprints. Some type of weapon or a staff could have produced these marks, Cupper suggests. Shallow grooves that extend for as many as 15 feet in some areas suggest that poles were dragged across the ground, he adds.
Earlier fossil and stone-tool finds indicate that people inhabited southeastern Australia by around 40,000 years ago, notes anthropologist Peter Brown of the University of New England in Armidale, Australia. Still, he cautions, ages assigned to the newly discovered footprints need to be verified by independent teams.
Brown says, “The most remarkable thing about the Willandra Lakes footprints is that they are preserved at all.”