Genesis has a clearly defined structural framework delineated by the repeated occurrence of the word toledoth, “the generations of.” This genealogical formula serves to introduce both genealogical and narrative sections of the book. In a sense, it functions either as a divider within the book, as is the case with genealogical lists 5:1; 10:1; 11:10; 25:12; and 36:1, or as a superscription to the narrative material that follows 6:9; 11:27; 25:19; and 37:2.
In every case toledoth is followed by the genitive of the progenitor (Skinner, 41) but as such emphasizes the progeny. Thus each toledoth summarizes what precedes and introduces what follows. In 2:4 the writer relates the beginning of human history to cosmic history and thereby introduces the Adam narrative. Ch. 5 concludes the story of Adam by listing his progeny, and it paves the way for the Noah narrative, which is introduced by the toledoth of 6:9. Similarly, ch. 10 and 11:10-26 summarize the progeny of Noah and set the scene for the story of Abraham, which is introduced by the toledoth of 11:27. So, too, Abraham's progeny through Ishmael is summarized in 25:12, while the Jacob narrative is introduced in 25:19. In turn, Isaac's progeny through Esau is summarized in 36:1, 9 and allows the toledoth of 37:2 to introduce the Joseph narrative.
It is possible to conclude from these observations of the occurrence of toledoth that in instances in which the formula is followed by a genealogy (5:1; 10:1; 11:10; 25:12; 36:1, 9), the emphasis is simply on the dimension of human history and is tangential to the major thrust of the book. It is offered, I suspect, for the sake of some kind of completeness, since it enables Israel to determine its relationships with its surrounding nations. That is particularly true in the genealogical lists of ch. 10, which hint at the basis of world population, and in 25:12-18 and ch. 36, which trace the progeny of Ishmael and Esau respectively. The genealogical lists of ch. 5 and 11:10-26 are simply concerned to fill in detail of the lineage from Adam to Noah and from Noah to Terah, Abraham's father.
The writer's obvious emphasis is on the Hebrew patriarchs and Israelite roots. That is the reason why the largest body of Genesis material (chs. 12-50) is concerned with a mere four generations of one family, specifically the Hebrew patriarchs and God's dealing with them. Contrast that with the many generations, personalities, and cosmic concerns of the first eleven chapters. It is the reason why the progeny of Ishmael is summarily dismissed in seven brief verses. Such disproportionate selectivity betrays the bias and intent of the writer. Genesis is not a book whose primary function is to trace the origin and hence the meaning of life in human historical terms. However, in the more significant use of toledoth in introducing narrative passages (2:4; 6:9; 11:27; 25:19; 37:2), the book functions at a theological dimension that transcends human relationships. It is the characters introduced by toledoth—Adam, Noah, Abraham, Jacob, and Joseph—who are the bearers of the revelation of God. Their history is a story of man's relationship with God—a theological history.
The function of the toledoth formulae, then, is to structure the book of Genesis into a unified composition, summarizing each major narrative section of the book and connecting it with the one that follows. In their highly organized use, they betray a major concern “to describe both creation and world history in the light of the divine will for a chosen people” (Childs, 149).