Modern humans hold ancient DNA
For a long time, we believed that Neanderthals and Homo Sapiens (modern humans) were two separate species. With the advent of DNA sequencing, however, it was discovered that Sapiens interbred with Neanderthals as they migrated from Africa 60,000 years ago. Another previously unknown hominid species, known as Denisovans, was also discovered at that time, and it interbred with Sapiens and Neanderthals, too.