At the judgment in Eden, God gave the promise of the “woman’s” Seed that was to crush the Serpent’s head. (Ge 3:15) This may have given rise to the idea of the Seed’s having a human line of descent, although not until Abraham was told that his Seed would be the means for blessing all nations was it specifically stated that the line of the Seed would travel an earthly course. (Ge 22:17, 18) This made the family genealogy of Abraham’s line of surpassing importance.

Following the Flood, Noah’s blessing pointed out that Shem’s descendants would be divinely favored. (Ge 9:26, 27) Later, God revealed to Abraham that what would be called his “seed” would be through Isaac. (Ge 17:19; Ro 9:7) It became obvious, therefore, that the identification of this Seed would require a very careful record of genealogy. Thus, in course of time, the line of Judah, the tribe that was promised leadership (Ge 49:10), and particularly the family of David, the kingly line, would be painstakingly registered. (2Sa 7:12-16) This record would provide the genealogy of the Messiah, the Seed, the line of extraordinary importance.​—Joh 7:42.

From Adam to the Flood. The Bible gives evidence of the existence of lists of family relationships from man’s beginning. At the birth of Adam’s son Seth, Eve said: “God has appointed another seed in place of Abel, because Cain killed him.” (Ge 4:25) Representatives of the line begun by Seth survived the Flood.​—Ge 5:3-29, 32; 8:18; 1Pe 3:19, 20.

From the Flood to Abraham. The line of Noah’s son Shem, who received Noah’s blessing, brought forth Abram (Abraham), “Jehovah’s friend.” (Jas 2:23) This genealogy, along with the above-mentioned pre-Flood one, constitutes the sole means for establishing the chronology of man’s history down to Abraham. In the pre-Flood list the record runs through the line of Seth, and in the post-Flood list, through Shem. It consistently states the time from a man’s birth to the birth of his son. (Ge 11:10-24, 32; 12:4) There are no other extensive genealogical lists covering this historical period​—an indication that these lists serve the double purpose of genealogy and chronology. In a few other instances the placing of specific events in the stream of time is accomplished by the use of genealogical information.​—See CHRONOLOGY (From 2370 B.C.E. to covenant with Abraham).

From Abraham to Christ. By God’s own intervention, Abraham and Sarah had a son, Isaac, through whom the “seed” of promise was to come. (Ge 21:1-7; Heb 11:11, 12) From Isaac’s son Jacob (Israel) came the original 12 tribes. (Ge 35:22-26; Nu 1:20-50) Judah was to be the kingly tribe, this being narrowed down later to the family of David. Levi’s descendants became the priestly tribe, the priesthood itself being restricted to Aaron’s line. In order to establish his legal right to the throne, Jesus Christ the King had to be identifiable as of David’s family and of the line of Judah. But because his priesthood was, by oath of God, according to the manner of Melchizedek, it did not require the Levitical descent.​—Ps 110:1, 4; Heb 7:11-14.