A new study has found that Neanderthals bred with our human ancestors some 100,000 years earlier than previously thought.

Experts said they've discovered that a five-year-old child who lived 140,000 years ago had parents from both species, per the U.K. Daily Mail.

The fossil - likely a female - was first unearthed 90 years ago in the Skhul Cave on Mount Carmel in what is now northern Israel.

A Tel Aviv University team and the French Centre for Scientific Research ran a series of advanced tests on the remaining bones, including a CT scan of the skull.

"Genetic studies over the past decade have shown that these two groups exchanged genes," lead author and professor Israel Hershkovitz said, per the Daily Mail.

"Even today, 40,000 years after the last Neanderthals disappeared, part of our genome -- 2% to 6% -- is of Neanderthal origin.

"But these gene exchanges took place much later, between 60,000 to 40,000 years ago. Here, we are dealing with a human fossil that is 140,000 years old.

"In our study, we show that the child's skull, which in its overall shape resembles that of Homo sapiens -- especially in the curvature of the skull vault -- has an intracranial blood supply system, a lower jaw, and an inner ear structure typical of Neanderthals."

That finding made the remains the earliest human fossil in the world to display features of both Neanderthals and Homo sapiens, the team said.

A recent study that was also carried out by Hershkovitz showed that Neanderthals lived in what is modern-day Israel as far back as 400,000 years ago.

The new findings suggested they encountered early humans that began leaving Africa around 200,000 years ago.

This human-Neanderthal type, which researchers have called "Nesher Ramla Homo" after the archaeological site where it was found, was the result of interbreeding between the two populations.

The child is so far the earliest evidence of the social and biological ties between these two populations over thousands of years.