Various Jokes: What Thing Walks On All 4 Then On 2 Then On 3

What thing walks on all 4 then on 2 then on 3? ~*~ a human ~*~ Wanna know how? Okay well, when you are young you walk on all 4. When you are older you walk on 2 legs. But when u get really old you have to use a cane~*~!