As an artist - especially a portrait artist - you have to become very familiar with the human skull. It is the foundation of the face. If you are ever going to accurately capture someone& likeness, you need to understand what lies beneath their skin.
Rare and Interesting Ancient Prehistoric ‘Classic’ Neanderthal Human Skull to BCE European). The is now in dispute - may actually be closer to or when Neanderthals became extinct as a separate subspecies.