To understand how Neanderthals, humans and chimpanzees are related, scientists compare their skeletons. The chimpanzee's small brain case, and arms and legs adapted to climbing, set it apart from the other two. Neanderthals, humans and chimpanzees all evolved from a common ancestor, so their skeletons are similar. But Neanderthals were broad and stocky compared to humans. Chimpanzee bodies are built for life in the trees.