What can ancient depressions in the ground tell us about our early ancestors? We've learned a lot.
In January, an international team of scientists from Morocco, France, Germany and Spain announced details of an intriguing discovery: a series of well-preserved human footprints thought to be 100,000 years old.
The footprints, believed to belong to a group of five people, were found on the rocky coast of a town in northern Morocco.
The study, published in the scientific journal Nature, adds to a growing body of research that is helping scientists piece together the hidden origins of humanity. But while the discovery is an archaeological feat, coastal erosion threatens the existence of these ancient footprints.
Here's what we know about this latest discovery and other ancient human traces scientists have discovered so far.
What did scientists discover in Morocco?
In June 2022, archaeologist Mounsef Sedrati was leading a field survey in an area south of Tangier focusing on rocks near the Moroccan coastline when his team discovered a depression in the ground in the city of Larache. I stumbled.
A closer look revealed that the depressions were footprints of various sizes. For Sedrati, an expert in coastal mechanics and marine geology 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, and very clear trajectory, and more and more,” Sedrati told Al Jazeera. Ta.The first traces were left by a healthy homo [sapiens] on sandy beach deposits from about 100,000 years ago. ”
A total of about 85 footprints were discovered, probably left by a group of five humans who were using this spot as a trail to walk towards the water. These are the first early human footprints discovered in North Africa and the southern Mediterranean.
The dimpled arches, rounded heels, and short toe marks confirmed that they were the footprints of Homo sapiens, or modern humans like us. We found that adults and children of different ages have different foot sizes.
But scientists still don't know what the group was doing there. Were they trying to collect food from the sea? Or were you simply sailing through the area and happened upon the beach route?
Sedrati's team studied the deposits at the site and the footprints themselves to determine how long they had been there.
Photostimulated luminescence dating is a research technique that helps archaeologists determine when the minerals and carbon around discovered artifacts were last exposed to heat and sunlight, and the researchers found that the prints We were able to estimate how old it is.
They traced the origin of the traces to the late Pleistocene, the time of the last ice age. The preceding Middle to Late Pleistocene, which included the period from 770,000 years ago to 120,000 years ago, is widely considered to be a time when ancient humans roamed the Earth, separate from modern humans.
The team used a drone to take 461 photos of the prints, used specialized software to process the images, and extracted 3D models to accurately measure the indentation and width of each print, allowing group members to I measured my age.
Larache's footprints likely remained intact due to a combination of factors, including location, soil type, and ocean waves, the researchers wrote in the study. The beach's location on a rocky platform allowed the tide to bury the clayey deposits that form the track, leaving it preserved until recent erosion exposed it again.
For Sedrati, who is of North African descent, the discovery was personal.
“You can imagine how proud I am to lead the research team that made this discovery, especially in a Moroccan city that is close to my heart,” he said, adding that geology and other The researchers added that they enjoyed collaborating with colleagues from other fields to achieve this discovery.
But the team still has work to do. Only part of the print has been processed and the team has a question.
“What were the climate and weather conditions like at the time? Where was the coastline, what was the sea level?” Sedrati asked.
Where else have ancient human footprints been found?
Finding footprints from thousands of years ago is rare, but not unheard of.
The oldest known human footprints were discovered in 1995. These were his set of three footprints belonging to the hypothetical “Eve” and were called “Eve's footprints.” They were discovered in the coastal town of Langebaan in South Africa's Western Cape province. Eve is thought to have lived about 117,000 years ago.
David Roberts, part of the team that discovered the tracks, said at the time that they were likely created on steep sand dunes during a storm, before drying sand filled the depressions and solidified.
The print measures 22 cm (8.7 inches), which is approximately the same size as a modern woman wearing a US size 7.5. “Eve” was probably around 122 centimeters (4 feet) tall.
In 2022, another research team discovered two human footprints on the roof of a cave in the same area. The state of preservation was not good. Although the deposits in which the footprints were made had eroded, the outlines of the footprints were still visible. The distance between the two footprints – 49 cm (19 inches) is consistent with the distance between the legs of an average human while walking – indicates that it is a separate species of modern humans, the hominid. This suggested to the research team that it was from one of our direct ancestors, rather than an animal. It is now extinct.
Beyond the African continent, ancient footprints have also been discovered in the United States. In 2009, a park ranger at New Mexico's White Sands National Park discovered the footprints, and he led a team of scientists who discovered thousands more footprints spread over 325 square kilometers (80,000 acres). These included child-sized footprints, and one set in particular showed a woman who appeared to have left a baby. Researchers in 2021 said they were likely created 22,800 years ago.
What do these discoveries tell us about prehistoric humans?
Paleoanthropologists (researchers who study the evolution of modern humans) believe that these prints, taken together, give us a snapshot of that time and give us a glimpse into what life was like for our early ancestors. He said it would be helpful to know what it was.
For example, one possibility is that ancient women painted their bodies with ingredients similar to modern cosmetics. The scientists who discovered Eve's footprints also discovered ocher, a colorful pigment, in the same area. It is believed that the body paint was applied for ceremonial purposes.
Scientists have also discovered hearths, showing that ancient humans knew how to make fire. Bone remains and stone tools also suggest that early humans may have first relied on animal carcasses for food, setting traps and hunting animals around 20,000 years ago.
But footprints also give scientists an estimated time frame to estimate when humans diverged and began moving across the globe.
Researchers have long believed that modern humans first arrived in Alaska and spread across North America some 13,000 to 16,000 years ago, after the last ice age.
But footprints left in New Mexico's White Sands Park disproved those studies. In the new scenario, humans may have already spread around New Mexico and traveled across the continent 23,000 years ago, when glaciers were still expanding and spreading across the region.
Unfortunately, many of these discoveries, including the White Sands and Larache prints, are threatened by changes in the landscape that are partly related to climate change. Sedrati's group noted in their study that rising sea levels are causing rocky beaches to collapse and may eventually disappear.