atavism
Atavism is the retention of features that are typically found in an evolutionary stage that is later in the human species' timeline. This can include features like the ability to walk on all fours, or the possession of teeth that are not typical for humans today.
Some people believe that atavism is a sign that the person is connected to the animal kingdom in some way.
Atavism is usually seen in animals that are close to the ground, like monkeys or apes.