Final answer:
Much of what we know about Neanderthals comes from mitochondrial DNA studies and evidence of interbreeding with modern humans. DNA evidence suggests that Neanderthals shared a common ancestor with modern humans and that interbreeding occurred between the two groups.
Step-by-step explanation:
Much of what we know about Neanderthals comes from mitochondrial DNA studies. DNA evidence suggests that Neanderthals interbred with modern humans and with local Neanderthal populations over multiple time periods. Additionally, genetic similarities between Neanderthals and modern humans have been found in European and Asian populations, indicating interbreeding between the two groups.