A period of ten generations passed between Adam and Noah, and so would another ten generations pass between Noah and his spiritual successor, one who would start from the point where Noah failed. That chosen one was to be Abraham, a scion of the line of Shem, whose descendants would constitute the children of Israel.
At this point in the narrative the biblical author returns to the genealogy of Shem, which he had interrupted earlier, to present in detail the lineage and descent of Abraham. In the process of doing this, he provides the careful reader with some intriguing bits of information.
11:10. These are the generations of Shem. Shem was a hundred years old, and begot Arpachshad two years after the flood. 11:11. And Shem lived after he begot Arpachshad five hundred years, and begot sons and daughters. 11:12. And Arpachshad lived five and thirty years, and begot Shelah. 11:13. And Arpachshad lived after he begot Shelah four hundred and three years, and begot sons and daughters. 11:14. And Shelah lived thirty years and begot Eber. 11:15. And Shelah lived after he begot Eber four hundred and three years, and begot sons and daughters. 11:16. And Eber lived four and thirty years and begot Peleg. 11:17. And Eber lived after he begot Peleg four hundred and thirty years, and begot sons and daughters. 11:18. And Peleg lived thirty years, and begot Reu. 11:19. And Peleg lived after he begot Reu two hundred and nine years, and begot sons and daughters. 11:20. And Reu lived two and thirty years, and