A human skull recovered from a cave in Romania was found to contain up to 10 percent Neanderthal DNA, providing clues into the early instances of interbreeding.

All humans hailing from outside of Africa have traces of Neanderthal DNA in them, making scientists aware that at some point in history the two species intertwined.

Exactly when or where that happened is unknown, but an ancient human skull recovered from a cave in Romania has offered some clues. 

It dates back roughly 40 thousand years, and an analysis of its jawbone revealed it contains 6 to 9 percent Neanderthal DNA. 

Considering that modern people carry only 1 to 3 percent, the skull places interbreeding in conside