You might look at the tools that are buried near them. This right over here, these are Paleolithic arrow, I guess, spearheads or tools right over here. Paleolithic is defined by more of these harder edges. You have Neolithic tools, which have more of these smoother edges. The Old Stone Age, New Stone Age right over here. And by looking at all of that, you have all of these scientists, you have these anthropologists, archeologists, paleontologists who are starting to piece together prehistory. And sometimes these techniques are done together.