**Saed News**: The fascinating discovery of these fossilized footprints has preserved an extraordinary and unexpected moment in time—when two distinct types of early humans walked side by side. This finding suggests that they were capable of coexisting as neighbors within a shared habitat.
According to the historical service of Saed News, more than 1.5 million years ago, two different species of ancient humans had a chance encounter along the shore of a lake—perhaps even locking eyes. These early predecessors of Homo sapiens were roaming a landscape teeming with wildlife, including giant scavenger storks standing 2 meters tall.
The fascinating discovery of these fossilized footprints—pressed into soft mud and later turned to stone over centuries—has preserved a remarkable and unexpected moment in time. It shows that two distinct species of hominins were capable of coexisting as neighbors (not enemies) within a shared habitat.
Kevin Hatala, lead author of the study on the footprints, said: “It’s surprising to find remains of two large-bodied hominin species of similar size within a single landscape.”
Hatala, an associate professor of biology at Chatham University in Pittsburgh, added: “We saw their footprints in a lakeshore environment. They were likely aware of each other’s presence. They could see each other—and may have even interacted.”
The first part of this discovery occurred in July 2021 during an excavation at Koobi Fora, on the eastern shore of Lake Turkana in Kenya, a site known for skeletal remains of several ancient human relatives. During that dig, a hominin footprint was discovered next to several others belonging to large birds. The team decided to re-bury the tracks in fine sand until a more thorough excavation could be undertaken.
That excavation took place in 2022, when Hatala and his colleagues unearthed 23 square meters of sediment and found 11 more hominin footprints aligned in a trail, indicating they likely belonged to a single individual. They also found three additional, separate prints oriented vertically.
Researchers also found 94 non-human footprints belonging to birds and hoofed animals resembling cattle and horses. The largest bird track measured 27 cm wide and likely belonged to a giant stork known as Leptoptilos.
“There’s a long trail with 12 hominin footprints,” said Hatala. “They were made at a walking pace, especially as they stepped through mud. But in the end, there's no clear destination.”
“It’s hard to say exactly what they were doing, but they were definitely walking through a muddy area. If you think of a lake shore or a modern beach, there’s a narrow zone where mud is ideal for preserving footprints—too dry on one side, too wet on the other. We were lucky they walked along almost a straight line.”
The three additional footprints were scattered vertically across the site. Hatala believes they were made by three different individuals, and that other footprints were likely erased by animals walking over the same surface.
Hatala and his colleagues couldn’t directly date the footprints, but they were found beneath a layer of volcanic ash called the Elomaling'a Tuff, which is dated to 1.52 million years ago.
Still, researchers are confident the footprints were made within a few hours or days of each other, since there are no gaps or cracks that would indicate prolonged exposure to the elements.
Scientists say the footprints were all preserved under a layered sediment blanket because fine sandy silt gently covered them shortly after they formed.
“The footprint layer was probably part of a delta system with lots of shallow, low-energy water and abundant mud,” Hatala noted.
The term hominin refers to all human-lineage species that arose after the evolutionary split from the ancestors of great apes around 6 to 7 million years ago. This group includes extinct close relatives like the Neanderthals, who disappeared about 40,000 years ago.
The research team concluded that the tracks were made by hominins from the species Homo erectus and Paranthropus boisei, the latter having a smaller brain. The long trail of footprints likely belonged to Paranthropus boisei, while the three scattered prints were made by Homo erectus. Skeletal remains of both species have been found at the site.
However, it wasn’t immediately clear the prints were made by two different species. Hatala, a specialist in foot anatomy, conducted detailed 3D imaging and analysis and determined that they reflected different walking, standing, and movement patterns.
Through field and lab tests, Hatala compared the prints with those of modern humans—including 59 barefoot individuals from the Dassanach community in Ethiopia—as well as fossilized hominin and chimpanzee tracks.
He found that the 12-step trail was outside the typical range of modern human footprints, unlike the other three prints, which resembled those made by modern humans.
“Homo erectus, from the neck down, looks very similar to modern humans and is considered the best candidate for our direct ancestor during that time,” Hatala said. “So we assume the more human-like prints were likely made by Homo erectus due to their human-like anatomy.”
Here, you see a fossilized footprint believed to have been made by Homo erectus, an ancient human species.
Hatala and colleagues reviewed older fossil data from the site and found evidence that the two species had overlapped in this region for a considerable time—possibly over 100,000 years.
“This is exciting because it suggests direct competition between the two was likely minimal. They didn’t seem to mind sharing the landscape or try to drive each other out,” Hatala said.
He added, “This area was probably dangerous, home to hippos, crocodiles, and other threatening animals. So both species likely had strong incentives to return to this area over and over during that long period.”
These footprints are the first physical evidence showing that distinct hominin species overlapped at the exact same time and place—avoiding predators and foraging together in ancient landscapes. Homo erectus survived for about 1 million years longer, while Paranthropus boisei went extinct a few hundred thousand years later, for reasons scientists still don’t fully understand.
Briana Pobiner, a research scientist and educator in the “Human Origins Program” at the Smithsonian National Museum of Natural History, said: “Finding footprints from not just one, but two species in the same area is surprising.”
“Maybe they were competing for food, or maybe they just looked across the green corridor at each other with caution—or perhaps they completely ignored one another.”
This is the first time footprints have shown that two species of hominins directly encountered each other, though genetic evidence has shown that Neanderthals interbred with Homo sapiens and Denisovans. In Siberia’s Denisova Cave, scientists discovered the remains of a girl whose mother was a Neanderthal and father a Denisovan.
According to Pobiner, boisei and erectus may have been similar enough to interbreed at times: “This finding tells us they lived in the same place at the same time—and literally walked side by side.”
