Drawing comparing human skull to Neandertal skull.
Some scientists believe that these ancient skulls may be the evidence of hybrids that are the product of human and hominid mating. Species that diverged from a common ancestor within a few million years still have the capacity and similar DNA to still be able to reproduce. To further observe this, scientists have experimented with hybridizing species that exist today and comparing the results they get with those of the cave skulls they have found. Yellow and olive baboons were interbred to see how the resultant generations would appear and what traits would be exhibited. The results showed that hybridization blurs the lines between species and makes it harder to detect differences among the species. Due to this, a theory has come up that Neandertals were not physically pushed to extinction by being out-competed by humans, but rather they slowly began to fade away by interbreeding with humans and leaving their mark in our DNA.