A long time ago, there was a man named Deucalion and his wife Pyrrha, who lived on top of a mountain. One day a flood occurred, killing all mankind except them.
After the flood subsided, the couple went to the oracle at Delphi to find out what they should do since all the rest of humanity had died in the flood. A loud voice told them that they should take their mother's bones and scatter them throughout the earth. When they heard these commands, they were saddened because they wanted to avoid defiling the bones of their dead mothers.
Deucalion figured out that what the oracle meant was that they should throw mother earth's bones onto the ground. So instead of defiling their dead mothers, they took some rocks and threw them onto the ground, thus creating humans!