How are the forelimbs of humans, the wings of birds, the wings of bats, the wings of insects similar, how are they different, and what do we think happened in the past evolution of these structures ? Solution All these structures mentioned, that is, the forelimbs of humans, the wings of birds, the wings of bats, the wings of insects have a similarfunction because they all are used for movement. But they are structurally very dissimilar. Hence they are also known as analogous characters. The independent evolution of characters in members of different species with similar function but differences in structure and ancestral origin is known as convergent evolution. This type of evolution leads to the formation of analogous characters or traits. The convergent evolution of flight of birds, bats and insects is known as functional convergence, as their function is similar. In the very past, there must have been a common ancestor, from whom the wings and forelimbs were evolved and structurally became different in the course of evolution..