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Why do almost all vertebrates have tails, even when they don’t seem useful, but apes and frogs don’t?
Stephen Johnson
Eugene, Oregon, US
All non-aquatic vertebrates descend from a common ancestor, a tetrapod of approximately 360 million years ago – which possessed a tail. The existence of the tail was primarily for balance, particularly when using only the rear legs, such as when feeding in trees. However, the tail evolved to have many uses, for example allowing primates extreme agility in the arboreal portions of forests.
It isn’t true that apes and frogs don’t have tails. Frogs have five different metamorphic life stages and possess a tail…
