An incredible new paper has just been published, and it is making a rather remarkable claim: despite going extinct around 30,000 years ago, Neanderthals have a tremendous impact on our current DNA, and even still live inside all of us. Scientists found that Neanderthal DNA comprises about 2 percent of the genomes of today’s humans who are of European and Asian heritage, but now scientists have found that Neanderthal DNA still influences how our very genes work.

It’s been a long time since humans and Neanderthals were part of the same species, splitting apart on the evolutionary tree 700,000 years ago. But interbreeding between the two species persisted until about 50,000 years ago, and as it turns out, that DNA is still around today, thanks to that interbreeding.

But there’s still a lot of mystery to this revelation. Although we know the genes are there, we don’t quite now how it works. Sometimes genes can manifest themselves in various strengths, other times they have no measurable impact on who we are. But it’s an important finding that could lead us on a journey to understanding more about how we came to be.

“Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression,” says geneticist and study co-author Joshua Akey of the University of Washington School of Medicine. “And those variations in gene expression contribute to human phenotypic variation and disease susceptibility.”

“We find that for about 25% of all those sites that we tested, we can detect a difference in expression between the Neanderthal allele and the modern human allele,” says the study’s first author, UW postdoctoral researcher Rajiv McCoy.