How the Neanderthals lost their Y chromosome
New genetic studies show that the Neanderthals replaced their male sex chromosome more than 100,000 years ago. They got their new chromosome from an early version of our own species.
When our ancestors left Africa some 60,000 years ago, they met other human species on their way. And the meetings became intimate. Genetic studies have shown that modern humans mixed genes with both Neanderthals in Europe and Denisovans in Asia. But new evidence indicates that this cross-fertilisation had begun much earlier.
Scientists from the Max Planck Institute in Germany isolated the Y chromosome from three Neanderthals that lived 38,000-53,000 years ago, then compared it with the Y chromosome of two Denisovans. Surprisingly, the Neanderthals’ Y chromosome was more like that of modern humans than those of Denisovans. It should be the other way around, because the Neanderthals and Denisovans development lines only separated hundreds of thousands of years after their common ancestors parted from ours.
The most likely explanation is that a group of early Homo sapiens left Africa long before the migration wave from which we descend. According to the scientists, these early migrants passed their Y chromosome on to the Neanderthals 100,000-370,000 years ago.
The discovery supports the theory that Homo sapiens left Africa in many waves. In recent years, several discoveries have been made that point in this direction. In 2018, a 180,000-year-old Homo sapiens jaw was found in Israel. And in Greece, scientists found a 210,000-year-old skull in 2019 that is also reminiscent of Homo sapiens. Our species’ history outside Africa seems to have been much longer than we used to think.