The dead are never really gone. In archaeology and the forensic sciences, that’s quite literally true
Though people tend to think that mortal remains quickly turn to nothing, in reality, the human body is very resilient and can persist for hundreds and even thousands of years.
Most people will have heard of Egyptian mummies, and how even as long ago as 2600 BC, people knew how to preserve their dead so successfully that they have endured until the present day. But even without human help, ancient human remains in South America have persisted as the climate dries the body out and slows down bacterial decay. Caves in less extreme environments can be dry and cold enough to preserve human remains, such as Schmerling in Belgium, which was where the first bones of our Neanderthal relatives were discovered.