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A new study suggests that human evolution may be more “bizarre” than previously believed.
It was once thought by experts that variations in climate played a major role in the evolution of hominins. However, recent studies from the University of Cambridge have revealed that hominid evolution may have been mostly driven by competition.
“We have been ignoring the way competition between species has shaped our own evolutionary tree,” said lead author Dr. Laura van Holstein, a biological anthropologist from Clare College at the University of Cambridge. “The effect of climate on hominin species is only part of the story.”
Most other vertebrates have the trait of interspecies competition, which causes an explosion in species evolution as each species adapts to occupy a new niche in the environment. But when every niche is taken, competition sets in, and this rapid evolution comes to an end.
“The pattern we see across many early hominins is similar to all other mammals,” van Holstein stated. “Extinction rates begin to rise when speciation rates peak and subsequently level out. This implies that a significant evolutionary element was interspecies rivalry.”
But things became considerably more strange when van Holstein looked into the evolution of our own genus, Homo.
“The more species of Homo there were, the higher the rate of speciation,” she stated. Therefore, something prompted the emergence of even more species once those niches were filled. In evolutionary research, this is nearly unmatched.”
Put another way, it seems that competition between distinct Homo species actually fueled the emergence of further Homo species—a total inversion of what one would anticipate from the history of the majority of other vertebrates.
What makes our evolutionary tree so peculiar, then?
Van Holstein, however, believes that it most likely has to do with the way we utilize technology.
“Adoption of stone tools or fire, or intensive hunting techniques, are extremely flexible behaviors,” van Holstein said. “A species that can harness them can quickly carve out new niches, and doesn’t have to survive vast tracts of time while evolving new body plans.”
Our forebears’ ability to use technology to compete for resources and space in many marketplaces likely contributed to their quick growth. This increased tool use may have had an impact on the evolution of Homo sapiens and the ultimate extinction of all other Homo species.
“These results show that, although it has been conventionally ignored, competition played an important role in human evolution overall,” van Holstein stated. “Perhaps most interestingly, in our own genus it played a role unlike that across any other vertebrate lineage known so far.”
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