What walks on four legs at dawn, two legs at noon, and three legs at dusk?

The answer? As a baby, a human goes about on all fours ("four legs in the morning"; morning = childhood), until he learns to walk, which he does so well into adulthood ("two legs in the afternoon"; afternoon = adulthood), until old age requires him to use a cane to support himself ("three legs in the evening", evening = old age), finally he dies ("no legs at night", night = death). So the answer is "a man".

The answer is a man:
 He crawls on all hands and knees as a baby,
 Walks on 2 legs as an adult,
 And walks using a cane in his old age.-HOPE THIS HELPS :D