Evolutionary science distinguishes between homology (the traits of two species derive from a common ancestor) and analogy (similar traits evolved independently in two species). The human hand is homologous with the bat’s wing since both derive from the vertebrate forelimb, as is recognizable by the shared arm bones and five phalanges. The wings of insects, on the other hand, are analogous to those of bats. As products of convergent evolution, they serve the same function but have a different origin.
