What 100,000-year-old footprints in Morocco tell us about early humans

What can indentations in the ground from ages ago tell us about our early ancestors? A lot, it turns out.

In January, an international team of scientists from Morocco, France, Germany and Spain published details of a fascinating discovery: a set of well-preserved human footprints believed to be 100,000 years old.

The footprints are thought to be from a group of five individuals and were found on a rocky beach in a northern Moroccan town.

The research, published in the science journal Nature, adds to a growing body of work that’s helping scientists piece together the evasive, true origins of the human race. But while their discovery is an archaeological feat, coastal erosion threatens the existence of these ancient tracks.

Here’s what we know about this latest find and about other ancient human traces that scientists have discovered so far.

What did scientists find in Morocco?

In June 2022, archaeologist Mouncef Sedrati was leading field research focused on boulders close to the Moroccan shoreline in an area south of Tangier when his team stumbled on indentations in the ground at the city of Larache.

On closer look, they discovered the indentations were footprints of varying sizes. To Sedrati, a coastal dynamics and marine geology expert at France’s University of Southern Brittany, it was an “exceptional” sight.

“We weren’t 100 percent sure at first with the first print, but little by little, we found a second, third, then a very clear trackway and more and more,” Sedrati told Al Jazeera.”That’s when the doubt disappeared. The initial traces were left by healthy Homo [sapiens] on a sandy beach sediment around 100,000 years ago.”

About 85 footprints were found in total, likely made by a group of five humans who were walking towards the water, using the site as a path. These are the first early human tracks to have been discovered in North Africa and the Southern Mediterranean.

How have the footprints survived for so long?

Sedrati’s team studied sediment in the location and the footprints themselves to determine how long they might have been there.

Optically stimulated luminescence dating, a research technique that helps archaeologists determine when the minerals or carbon surrounding discovered artefacts were last exposed to heat or sunlight, allowed the researchers to estimate how old the prints might be.

They pegged the origins of the marks to the Late Pleistocene era, the period during which the last Ice Age happened. The preceding Middle to Late Pleistocene, encompassing the periods from 770,000 to 120,000 years ago, is broadly believed to be the age when ancient humans – separate from modern humans – roamed the earth.

Using a drone to take 461 photographs of the prints, the team processed the images using specialised software and extracted 3D models to accurately measure the depression and width of each print, and to gauge the ages of the group’s members.

The Larache footprints likely remained intact because of a combination of factors, the researchers wrote in the study, including their location, the soil type and the sea waves. The position of the beach on a rocky platform allowed the tides to bury the clay sediments forming the tracks, keeping them preserved until a recent erosion exposed them again.

For Sedrati, who is of North African descent, the discovery is personal.

“You can imagine how proud I am to lead the research team that made this discovery, even more so in a Moroccan city that is close to my heart,” he said, adding that he relished working with colleagues from other fields like geology to complete the study.

But there’s more work for the team to do. Only part of the prints have been processed, and the team has questions.

Where else have ancient human tracks been found?

Finding footprints that are thousands of years old is rare but not unheard of.

The oldest known human tracks were discovered in 1995. These were a set of three imprints belonging to a hypothetical “Eve” and called “Eve’s footprints”. They were discovered in Langebaan, a coastal town in South Africa’s West Cape province. “Eve” was thought to have lived about 117,000 years ago.

David Roberts, who formed part of the team that discovered those prints, said at the time that they were likely made on a steep dune during a storm before dry sand filled the indentation and hardened.

The prints measured 22cm (8.7 inches), about the same size as a modern woman wearing a US size 7.5. “Eve” was probably about 122cm (4ft) tall.

In 2022, another team of researchers found two human tracks on the roof of a cave in the same area. They were not well-preserved. The sediment the imprints had been made in had eroded, but the outlines of the footprints were still visible. The distance between the two tracks – 49cm (19 inches), consistent with the distance between an average human’s legs while striding – suggested to the team that it was from one of our direct ancestors, rather than Hominini – another species of the modern human that is now extinct.