History was made a decade ago, when a team of researchers completed the first whole sequence of a Neanderthal and learned that the genetic differences between them and modern humans reached 0.3%.
At that point in time, it was argued that 2% of the DNA found in all modern people without an African ancestry comes from Neanderthals, but additional research has shown that it is present in all living individuals. However, details about the Y chromosome across Neanderthals and Denisovans had remained a mystery.
Many of the fossils analyzed during the initial study were of female origin. The researchers had access to bones and teeth from Neanderthals and Denisovans, but the amount of DNA found in them was considerably lower, and since Y chromosomes are tied to males, the amount of potential information was limited.
A different team of scientists has recently announced that it has managed to sequence Y chromosomes from fossils tied to two Denisovans and three Neanderthals. The results are quite fascinating, revealing more information about human evolution and the genes that can be observed as a result of human interbreeding.
Previous research inferred that Denisovans and Neanderthals could be associated as sister groups, while early humans were a more distant relative of the two, a theory that should have been confirmed by the Y chromosomes. With the help of an advanced tool, the researchers managed to extract chromosome sequences from fossils that were considered too damaged to be usable in the past.
Tests have revealed that the Y chromosome of Neanderthals is more similar to the Y chromosome of early humans in comparison to that of Denisovans. It is estimated that a lineage division took place more than 700,000 years ago. Interbreeding between early humans and Neanderthals has also led to the replacement of the Neanderthal Y chromosome with the early human chromosome in the long run.
The study has been published in a scientific journal.