Traditionally, climate has been thought to be the cause of the emergence and extinction of human species. However, interspecific competition is known to play an important role in most vertebrates. A new study shows for the first time that competition has been the basis of speciation (the rate at which new species emerge) over five million years of human evolution.It also means that our speciation patterns homo The pedigree was different from most others.
a homo heidelbergensis, Neanderthals and Cro-Magnons. Image credit: SINC / Jose Antonio Peñas.
“We have ignored how competition between species has shaped our own evolutionary tree,” says Dr Laura van Holstein, an anthropologist at the University of Cambridge.
“The effects of climate on the human species are only part of the story.”
“In other vertebrates, species form to fill ecological niches. Darwin's finches, for example, have evolved large beaks for cracking nuts, while others have evolved large beaks for eating certain insects. Some have evolved small beaks to accommodate them. Once their respective resource niches are filled, competition ensues, no new finches emerge, and extinction takes over.”
Dr Van Holstein and Professor Robert Foley from the University of Cambridge used Bayesian modeling and phylogenetic analysis to show that, like other vertebrates, most species of humans formed when competition for resources and space was low. It was shown that
“The pattern seen in many early humans is similar to all other mammals,” van Holstein says.
“The speciation rate increases, then levels off, at which point the extinction rate begins to increase. This suggests that competition between species was a major evolutionary factor.”
However, when the authors analyzed our group, homothe findings were “bizarre.”
for homo The pattern of evolution of the lineage leading to modern humans suggests that interspecific competition actually led to the emergence of even newer species, a complete departure from trends seen in almost all other vertebrates. It's a reversal.
“The more types there are, the more homo The more there are, the higher the rate of speciation,” Dr. van Holstein said.
“So once those niches were filled, something caused more species to emerge. This is almost unprecedented in evolutionary science.”
The closest comparison she found was a species of beetle that lives on the island. On islands, confined ecosystems can produce unusual evolutionary trends.
“The evolutionary patterns we see across species are homo “The direct link to modern humans is more closely related to island beetles than to other primates or other mammals,” Dr van Holstein said.
