Neanderthals and modern humans may have split hundreds of thousands of years earlier than thought, a new study suggests.
The study, published Wednesday in the journal Science Advances, details that Neanderthal teeth — discovered in the Sima de los Huesos cave in Spain— show evidence that Neanderthals and Homo sapiens may have split much earlier than thought, more than 800,000 years ago.
Ancient DNA has generally shown modern humans split from the last common ancestor around 400,000 years ago, the study said. However, some other studies have shown the split occurred around 550,000-765,000 years ago. Due to small variations in studies of DNA and fossils, however, the exact estimates can be difficult to determine.
The teeth discovered in the Sima de los Huesos cave, however, were smaller than expected, as various human ancestors’ teeth evolved to become smaller over time, and their nature looks too modern for their age, the study said.
Because of the nature of the teeth, there would have had to been “unexpectedly rapid dental evolution” — or, Neanderthals and humans have split earlier than previously thought, which the study suggests is the most likely scenario.
“When we look at these teeth, they are very similar to the teeth of later Neanderthals, even though they are much older,”Aida Gómez-Robles, an anthropologist at University College London and the study’s author told the Smithsonian. “In this study we’ve tried to examine the amount of time that these early Neanderthals would have needed to evolve this dental shape, [which] is so much like the dental shape of Neanderthals that are much later.”
Hybridization between Neanderthals, Denisovans and modern humans could have caused the fast dental evolution. However, the study said the anatomy of the teeth and what is known about genetic hybridization does not give strong support for that theory.
It is more likely humans and Neanderthals split more than 800,000 years ago, the study suggested, making ancestors of modern humans more distant that has been generally thought.
