Just over two decades ago, many believed that human footprints older than 50,000 years were exceedingly rare and elusive. At that time, only four sites in Africa had been reported. Notably, the Nahoon site in South Africa, discovered in 1966, was the first-ever hominin track site to be described.
In a recent publication in Ichnos, the prestigious peer-reviewed journal for plant and animal traces, a team of dedicated researchers shed light on the ages of seven recently identified hominin ichnosites along South Africa's Cape south coast. These remarkable findings now join the esteemed "South African cluster of nine sites."
Through their meticulous investigations, the team uncovered a wide range of ages among the sites. The most recent among them dates back approximately 71,000 years, while the most astonishing find is an ancient footprint that dates back 153,000 years, representing the oldest footprint attributed to our species, Homo sapiens, thus far.
New dates serve to corroborate existing archaeological record
These newly established dates serve to corroborate the existing archaeological record. Together with other evidence from the same era, including the development of sophisticated stone tools, artistic expressions, jewelry and evidence of shellfish harvesting, it becomes increasingly evident that the Cape south coast served as a region where early anatomically modern humans thrived, evolved and ultimately dispersed from Africa to other continents.
Significantly, the track site cluster along the Cape Coast of South Africa exhibits striking differences when compared to its East African counterparts. The East African sites, with ages ranging from 3.66 million to 7 million years, showcase tracks made by earlier hominin species such as Australopithecines, Homo Heidelbergensis and Homo Erectus.
In contrast, the South African sites attributed to Homo Sapiens are substantially younger. These tracks are often fully exposed upon discovery, embedded within aeolianites - rocks formed from ancient dunes.
However, the unique nature of the South African sites also presents challenges. Due to their exposure to the elements and the coarse composition of the dune sand, they are not as well-preserved as their East African counterparts and are susceptible to erosion. This necessitates swift action by researchers to record and analyze the tracks before they succumb to the forces of wind and ocean.
To determine the age of these aeolianite deposits, researchers employ the reliable dating method of poetically stimulated luminescence. This technique measures the time elapsed since the grain of sand was last exposed to sunlight, indicating the duration of burial.
The Cape South coast, with its abundant quartz grains and ideal conditions of ample sunshine, wide beaches and wind-driven sand transport, proves to be an excellent location for this dating method. It ensures that any pre-existing luminescence signals are fully erased, providing accurate and reliable age estimates. This method has played a pivotal role in dating previous finds in the region.
The overall date range of the hominin ichnosites, spanning from approximately 153,000 to 71,000 years old, aligns with findings reported from similar geological deposits in the region. Notably, the oldest track site, dating back 153,000 years, was discovered in the picturesque Garden Route National Park, located to the west of Knysna on the Cape South coast.
Furthermore, the previously dated South African sites, Nahoon and Langebaan, yielded ages of around 124,000 years and 117,000 years, respectively.