Comparative anatomy is the study of similarities and differences in the anatomy of different species, with the aim of understanding their adaptive changes as they evolve. It is closely related to evolutionary biology and phylogeny, which is the evolution of species. Scientists use comparative anatomy to trace evolutionary relationships between species and to classify them based on their similarities and differences.

The study of comparative anatomy dates back to the 16th century, with the work of French naturalist Pierre Belon, who showed that the skeletons of humans and birds are constructed of similar elements arranged in the same way. Since then, knowledge of comparative anatomy has advanced rapidly, with the work of many scientists, including Edward Tyson, Georges-Louis Leclerc, comte de Buffon, and Louis-Jean-Marie Daubenton.

Two major concepts of comparative anatomy are homology and analogy. Homologous structures are structures in different species that have the same evolutionary origin, regardless of their present-day function. Analogous structures, on the other hand, may resemble each other because they perform the same function, but they have different evolutionary origins and often a different structure.

Comparative anatomy has long served as evidence for evolution, indicating that organisms share a common ancestor. It has been used extensively by scientists, including Charles Darwin, to advance the theory of evolution and to explain the structural differences between species as arising out of their evolutionary descent by natural selection from a common ancestor.

In summary, comparative anatomy is a field of study that helps scientists understand the similarities and differences in the anatomy of different species, and how they have evolved over time. It is a crucial tool for tracing evolutionary relationships between species and for understanding the process of evolution itself.