Competition between species played a significant role in the rise and fall of hominins, according to a new study from the University of Cambridge. Traditionally, climate has been considered the main factor in the emergence and extinction of hominin species, but interspecies competition also played a crucial role. The study, published in Nature Ecology & Evolution, reveals that competition was fundamental to the formation of new species over five million years of hominin evolution. This pattern of species formation in the Homo lineage is unique and different from other vertebrates.
Lead author Dr. Laura van Holstein used Bayesian modeling and phylogenetic analyses to show that most hominin species emerged when competition was low. However, the Homo lineage, which eventually led to modern humans, experienced a different evolutionary pattern. In the Homo lineage, competition between species actually led to the emergence of more new species, contrary to the trend seen in other vertebrates. This unusual pattern is similar to that seen in island-dwelling beetles and sets the Homo lineage apart from other primates and mammals.
Van Holstein created a new database of hominin fossil records to reevaluate the start and end dates of known hominin species. By using data modeling to account for factors affecting fossilization, she determined that some species previously thought to have evolved through anagenesis actually budded off from existing species. This means that more hominin species may have coexisted and competed for resources than previously assumed. The adoption of technology, such as stone tools or fire, by early Homo species may have enabled them to rapidly carve out new niches and drive the exponential increase in the number of Homo species detected in the study.
While early hominin species like Paranthropus evolved physiologically to expand their niche, the unique evolutionary pattern in the Homo genus may have been driven by technology. The ability to use technology to generalize and quickly adapt to new environments allowed Homo species to outcompete other hominins. Ultimately, Homo sapiens emerged as the ultimate generalists, able to thrive in various ecological niches. This competition with a highly adaptable generalist species like Homo sapiens may have contributed to the extinction of other Homo species.
Overall, the study demonstrates that competition played a crucial role in human evolution, particularly in the Homo lineage. This competition-driven evolutionary pattern in our own genus sets us apart from other vertebrates. The findings suggest that competition, combined with the adoption of technology, shaped the evolution of Homo species and may have contributed to the success of Homo sapiens as the dominant hominin species. By reevaluating the role of competition in hominin evolution, the study provides new insights into the complex factors that influenced the rise and fall of early human ancestors.
