Umm... backtracking on human life?
Cane+ 2 legs= 3 legs
2 legs
2 legs+ 2 hands= 4 legs
I heard this riddle. It was called the riddle of the Sphinx.
What starts with 4 legs at dawn, 2 legs in the afternoon, and 3 legs at night?
A person, because when you are a baby, you crawl on all fours.
Then you learn to walk.
And finally, you may use a cane when you grow old and need the support.