Hearing is pretty essential if you're a pedestrian, when you're not in an environment with sidewalks and traffic lights everywhere. When I'm walking around whe

Hearing is pretty essential if you're a pedestrian, when you're not in an environment with sidewalks and traffic lights everywhere. When I'm walking around where I live (in two different countries) I have to constantly be aware of traffic sounds behind me. I can think of a number of other situations where lack of hearing would be a disadvantage, or downright dangerous. You can live without a sense of smell too. But I for one find it extremely useful when a quick sniff tells me some food stuff which otherwise looks fine has actually gone off.