It is not just humans, chimpanzees and gorillas that don't have tails. Other apes (A)________ orang-utans, bonobos and gibbons do not have them (B)________.

Basically, tails are (C)________ to provide balance for animals, particularly those that might live (D)________ trees. A tail counterbalances the weight of the head at the front of the body. (E)________ humans became more upright and some apes started to use arms for more than just (F)________, the need for a tail for balancing became smaller, so over time and through evolution, it faded out.

(G)________, we do have the remains of a tail — the bottom three or four vertebrae of the human spine are fused together to form the tailbone (coccyx).

This still has a use, anchoring muscles such as the one of your bottom, and it still really hurts if you fall on it.