Everybody loves to read lists of names, right? Not usually, but it’s different if those names bear a special meaning to us. This list symbolizes Israel’s heritage, their own ancestors whom God rescued from famine and brought to Egypt in a time when Egypt welcomed them.
Following are some thoughts about the list. The list is more interested in the ancestors than in precise chronology. For example, of those recorded as going down to Egypt, the timeline does not easily permit Pharez to be old enough to have already fathered Hezron and Hamul (46:12). But because the narrator has noted the deaths of Er and Onan (46:12), and because Pharez inherits Er’s line via Tamar’s exploitation of levirate custom (38:14, 25-30), Pharez’s first two future sons might count for Judah’s sons the way that Joseph’s first two counted as Jacob’s sons (48:5). (The firstborn always received a double portion of the inheritance.)
The narrator enumerates those who came to Egypt with Jacob. These were far more numerous than the one heir in whom Abraham found the promise fulfilled, yet also a far cry from “As the stars are, so shall your seed be” (15:5; 22:17; cf. 26:4). They remained few in number, but the numbers of those who would leave Egypt generations later would indeed dwarf these figures many times over (even if, as many scholars suggest, they include an element of ancient population hyperbole)—virtually innumerable, as the stars were thought to be (Deut 1:10; 28:62). (Undoubtedly there were also others who came with Jacob besides those in the list, but these are his “direct descendants” [46:26, NASB, NIV; cf. 46:6-8]; other workers may have been assimilated into the tribes at a later time, perhaps during Israel’s enslavement in Egypt.)
How does the narrator calculate? The grandsons listed in 46:8-15 total 25 (of whom two died in Canaan), plus two great-grandsons; to these we may add the six sons, bringing the total to either 31 or 33 (depending on whether one subtracts the two who died in Canaan and thus did not come to Egypt); Dinah is also named along with other daughters who are not named (46:15; cf. 37:35), but the total count remains 33 (46:15). The grandsons listed in 46:16-17 total 13, plus a granddaughter and the two sons, for a total of 16 (46:17). The grandsons listed in 46:20-21 total twelve, plus the two sons, totalling 14 (46:22). The grandsons in 46:23-24 number five, plus the two sons, totalling seven (46:25). The total of the totals yields seventy (46:27), or with Joseph and his two sons subtracted, 66 (46:26). Seventy minus three should be 67; the 66 figure could have subtracted Jacob himself, but he does not figure in the original count. Surely Jacob had other daughters besides the two named in the list; the sons’ wives are also not counted (46:26; we do not hear whether any of Jacob’s own wives remain alive at this point).
All of this suggests either that Genesis’s first audiences were very bad at math or, more likely, that seventy is selected as a rounded number. Why seventy? Recall the seventy nations of Gen 10. God started humanity over with Noah (http://www.craigkeener.com/why-would-god-send-judgment-genesis-6-9/), but promised not to again destroy the earth with a flood; this time he starts humanity over in a new way, through Jacob’s children and the promise that their seed bears for the future. Through them, God would restore the worship of the one true God to humanity, particularly to those who would become part of a new humanity of God’s true followers. Looking back at history, we can marvel as we see how God used Israel as an agent of his purposes for the world—a small people here, but with an immeasurable influence on the destiny of humanity as a whole.