According to one version of the Mesopotamian flood myth, Utnapishtim was the wise man who alone survived the great flood that was sent to eradicate humanity. The gods Anu, Enlil, Ninurta and Ennugi decided to destroy humankind, having grown tired of their ways. Oh, those humans, with their ways!
However, Ea, the water god, warned Utnapishtim of the conspiracy, and told him to build a great boat, and in it store the seeds of all life. He did it, and loaded it with the said seeds, his cattle, his family, and an ass-load of birds. A filthy rain came for six days and six nights, and the people despaired. On the seventh day it ceased, and all that was left of humanity was a vast heap of thick mud, and Utnapishtim’s ship. He sent out birds to look for land, and eventually a raven found some, prompting Utnapishtim to place offerings to the gods in gratitude. Utnapishtim was granted the immortality of the gods in return for his saving of humanity and appeasing of the mesopotamian pantheon.
Later on, Gilgamesh, (ever heard of him? He’s kind of a big deal) who was a descendant of Utnapishtim, tracked him down to learn of him the secret of immortality. Long story short, he gets rejected.
Now, if this story sounds familiar, that’s because it is. Indeed, the biblical Noah is an analog of Utnapishtim, though the Sumerian/Mesopotamian/Babylonian deluge story was written long before the Noah of the Torah. Deluge myths are found all over the world. People move, stories move, and myths morph into other myths. An argument for cultural diffusion, if you look at it that way. Or, perhaps, we’re all just coded to have similar developmental paths, prompting similar stories to crop up in global religions? That’d be the parallel development argument. Me, I’m a diffusion guy.