Homology is the study of shared features between taxonomic clades, such as how all tetrapods, from amphibians to mammals, possess fingers, and is something that can only be explained by evolution. For example, what intelligent designer would give whales fingers and leg bones enveloped inside of a fleshy membrane, complete with shoulders, instead of giving them fish fins, and what intelligent designer would give whales lungs instead of enabling them to filter oxygen through the water like fish do?
These are the hallmarks of evolution, not creation. Evolution explains homology, Creationism doesn’t. It is as the late, and great, eminent Ukrainian evolutionary biologist Theodosius Doubzhansky once said:
Biology only makes sense in the light of evolution.
Homology is just one of many things in modern biology that can only be explained by evolution. Homology is indicative of common descent, not common design, as some Creationists like to claim. No intelligent designer would give whales lungs, after all.
Homology as a science was first devised by the great French anatomist and paleontologist Georges Cuvier himself, widely regarded to be the “Founder of Paleontology”, and who also happened to be a creationist, albeit not a young-earth creationist, he died a quarter of a century before Darwin published his seminal masterpiece On the Origin of Species (1859).
This is the second entry of a series of essays explaining basic evolutionary biology, the first can be found here.