What does Genesis 5:6 mean?

The pattern of this chapter of genealogy is repeated now for the second of the ten generations from Adam to Noah. Seth fathered his son Enosh at 105 years old.

We know from the end of chapter 4 that the birth and life of Enosh was something of a turning point: "At that time people began to call upon the name of the LORD" (Genesis 4:26). We don't know exactly what that means, but Enosh helped establish Seth's line as one characterized by worshipping and depending on God.

Another often-confusing feature of these genealogies are names, or names similar to, those in the lineage of Cain. This is no different from the modern trend of using common names, or derivatives of names. The line leading from Cain and the line leading from Seth are not only separate, they will end in separate dates. Cain's line will be cut off by the upcoming flood.

Besides faster population growth, another advantage of these long lifespans is the testimony of each generation. In this early world, it was possible for a child to hear directly from someone who had seen and lived the events of centuries past.