The Croods behave like Neanderthals in comparison to Guy, who is a Homo Sapiens. Guy mentions their sloping foreheads and extreme body hair, both of which set Neanderthals apart from Homo Sapiens. This clip also teaches that only Homo Sapiens have mastered fire, which set them apart from Neanderthals.
This clip explains the known history of the Neanderthals, who were the closest relatives to the modern human in the family tree. They lived about 400,000 - 40,000 years ago. This clip discusses their habitat and the evolutionary adaptations that may have allowed them to survive a cold, glacial ecosystem. It then speculates the leading theories surrounding their mysterious disappearance.
Beakman tells a story about the theory of how Neanderthals invented the wheel and why. They explain that having wheels reduces friction and makes it easier to move things. Beakman demonstrates this using a wagon.
When the Mammoths are faced by the smell of the Neanderthals, they host a meeting where they discuss intervention. They decide that the humans must take after the animals and learn how to bathe themselves.