What's the riddle of the Sphinx. Who answered it. What is the answer to this riddle

The riddle {was; 'What} is the creature that walks on four legs in the morning, two legs at noon and three in the evening?' The hero Oedipus gave the answer, 'Man,' causing the Sphinx's death. quite right Smartie,

an goes on four legs (crawling) when a baby, on two legs for most of it's life and needs a walking stick in old age