All creatures can be studied and classified in accordance to the discipline of anatomy, the branch of biology that is predominately concerned with the study bodily structures and mechanisms. Throughout history, using anatomical distinctions to compare, classify, and organize animal species into different groups has led to many scientific advancements and discoveries. This specific practice is called comparative anatomy and has also proven useful when studying human bodies, though it is critical to make any such classifications based on real biological differences rather than culturally defined stereotypes.