Human teeth are upright, not slanting outwards like those of apes, and they are
roughly even in height. Such characteristics are not very useful for ripping or tearing
food and seem better adapted for grinding and chewing. They are also very helpful in
making sounds such as f or v. Human lips have much more intricate muscle interlacing
than is found in other primates and their resulting flexibility certainly helps in
making sounds like p, b and m. In fact, the b and m sounds are the most widely