One of the greatest mysteries in human history is what happened to another species of humans, known as homo neanderthalensis. Although they looked similar to us, they had notable physical differences, such as their longer brow, lack of pelvis, and larger brains. We have no idea what happened to them!
Some scientists believe that their habitats gradually wore down and became unsuitable to support them. Others believe that early homo sapiens fought and killed them all. But all humans have traces of Neanderthal DNA in them – some of us more than others! This DNA can affect your immune system and other things.