Research Raises Questions About the Role of Competition in Human Evolution
Turkana Basin Institute, Nairobi, Kenya – November 28th
Members of the Koobi Fora Research Project in collaboration with National Museums of Kenya and Turkana Basin Institute are co-authors of a publication with Kevin Hatala, Ph.D., associate professor of Biology at Chatham University in Pittsburgh, PA.
This new study published in Science provides the first direct evidence of two different fossil human species, Homo erectus and Paranthropus boisei, occupying the same immediate landscape and likely interacting with each other. While skeletal fossils have long provided the primary evidence for studying human evolution, new data from fossil footprints are revealing fascinating details about the evolution of human anatomy and locomotion, giving further clues about ancient human behaviors and environments.
“Fossil footprints are exciting because they provide vivid snapshots that bring our fossil relatives to life – with these kinds of data, we can see how living individuals, millions of years ago, were moving around their environments and potentially interacting with each other, or even with other animals,” says Hatala. “That’s something that we can’t really get from bones or stone tools. The insights they give us, and the questions they raise, can be rather unique. For example, until now we have struggled to find the necessary data to know whether and how ancient human species may have coexisted and interacted during the early Pleistocene.”
“We have known that the two species exist at the same time period from the fossil remains found at Lake Turkana, but it is the first time that we have footprints from the same lake shore environments, indicating that they must have interacted to some degree in these habitats. ” Dr. Louise Leakey, Koobi Fora Research Project.
The fossil footprints were found in 2021, when Cyprian Nyete and other members of the field team from the Turkana Basin Institute were excavating skeletal fossils from overlying sediments. Richard Loki was a member of that excavation team and he recognized the first hominin footprint. Dr. Louise Leakey then assembled a team and coordinated the excavation of the footprint surface, led by Drs. Hatala and Roach and Mr. Nyete, in July of 2022.
The research team also expanded its analyses to other fossil footprint sites known from the surrounding area and they found more evidence that these two species occur together, at sites spanning up to 200,000 years. This combination of data suggests low to neutral competition between these two species, which may have enabled their long-term coexistence during the early Pleistocene. Later, environmental shifts could have impacted resource availability, increasing competition and potentially driving the behavioral adaptations that have come to define our genus. Resolving these kinds of questions may be possible in the future. “Documenting the strata revealed that are many more trackway surfaces that could be excavated nearby,” says Kay Behrensmeyer, a co-author from the Smithsonian’s National Museum of Natural History who studied the paleoenvironmental context of the trackways. “These might hold more clues that could address questions about how different hominin species interacted, what they were doing wading in the shallow water, and why this behavioral pattern recurred over 200,000 years.”
During this time and place in human evolution – about 1.5 million years ago in the Turkana Basin of Kenya – it has long been hypothesized that these fossil human species coexisted together. Homo erectus, a possible direct ancestor of ours, persisted for more than one million years after this. The other, Paranthropus boisei, went extinct within the next few hundred thousand years.
“Perhaps changes to climate influenced resource availability and that led to the extinction of Paranthropus and the persistence of Homo,” Hatala adds. “This is a hypothesis that will require further testing, and we’re hopeful that by combining fossil footprints with other kinds of paleontological and archeological data, we might be able to build a better understanding of how factors like competition and niche partitioning played a role in our evolutionary history.”
