“Now these are the generations of Perez.” Perez was a son of Judah by Tamar, and he is in the genealogy of Jesus Christ (Matt. 1:3; Luke 3:33). The genealogy of Perez has been considered incomplete by almost every scholar because the generations from Salmon to David, which are Salmon, Boaz, Obed, Jesse, and David, cover a long period of time. Those generations cover the last years of the Book of Joshua, the time of the Book of Judges, and the time in 1 Samuel until the birth of David. That time, from the year that Joshua crossed the Jordan and conquered Jericho, which was when Salmon would have likely married Rahab, until the birth of David, was a period of 365 years, which most scholars think is too long a time for only four generations to be born.
However, the genealogy is that of Jesus Christ, and it is given four times in Scripture and all four genealogies completely agree (Ruth 4:18-22; 1 Chron. 2:4-15; Matt. 1:3-6; Luke 3:31-33). While it is true that some genealogies in the Bible are incomplete, the genealogy in Matthew 1 being a famous example, no genealogy that is recorded in the Bible in exactly the same way in four different books had ever been shown to be incomplete. Furthermore, the genealogy in Luke has never been shown to be incomplete, so it seems that even if the other three genealogies were to skip some generations in David’s line, Luke would not. The reason that the genealogy of David has been assumed to be incomplete is based on the assumption that there is too much time between Salmon and David to bridge that gap in four generations. But while covering that time period in four generations seems unlikely, it is not impossible.
If we take the genealogy in Ruth, Chronicles, Matthew, and Luke as being accurate, then we have a huge key as to when the Book of Ruth and other events occurred in the Judges period. Spanning the time gap in Judges requires that the fathering age of the men in the genealogy be between 90 and 100 years, which is not the norm, but neither is it impossible, especially when we consider that God was working behind the scenes to build the genealogy to Christ, which had already had divine intervention with Abraham, Isaac (Jacob was born when Isaac was 60), and Jacob (Jacob married Rachel and Leah at age 84, then started having children). The Bible names some people who, after the Flood, either fathered children at age 100 or older, or could have, for example, Shem (Gen. 11:10-11), Abraham (Gen. 21:5), and Moses (Deut. 34:7). Also, Caleb at age 85 said he was as strong as he was at age 45 (Josh. 14:10-11) and so it seems he could have fathered children then and for years to come.
The Bible implies that Boaz was an old man when he married Ruth (Ruth 3:10), and it says that Jesse was an old man while David was still very young (1 Sam. 17:12), so we have some solid biblical evidence that the men of those generations were very old. Also, it is generally the case that older men do not father children because their wives have stopped being able to bear children. But in the biblical culture older men often married much younger women, and that could have happened with at least three of the four men in this genealogy, and especially so since the men in this genealogy seem to be men of means. For example, we know that Ruth was young but married Boaz when he was an old man, and part of her reason for that was so she and Naomi could be well taken care of. Also, long life runs in families, and we already know that at least two of the four men were old when they had sons, so that makes it more likely that the other men in the genealogy could have had long fertile lives as well.
Salmon’s age when he married Rahab, and when Rahab gave birth to Boaz are not known, but Salmon would have normally have had to have been 20 years old to be counted in the army (Num. 1:3), although in the case of the conquest of Canaan younger men might have joined the fight. Men who fought would have the privilege of taking a wife of the women who were captive (Deut. 21:10-12). So Salmon could have been quite young when he married Rahab and not have fathered a son in the genealogy of Christ for many years.
The time span for the genealogy from Salmon to the birth of David can be calculated in part by knowing that there were 480 years from the Exodus to the fourth year of Solomon, when the Temple foundation was laid (1 Kings 6:1). So the time span would be 480 minus 4 years for Solomon, minus 71 years for David’s life and reign (he was born the year before he turned one year old), minus the 40 years wandering in the desert before crossing the Jordan and conquering Jericho, and that would equal 365 years. For that 365 years to be spanned by the life of Salmon, Boaz, Obed, and Jesse before their sons in the genealogy of Christ were born would mean that the average age of those men when their sons were born was 365 divided by four, or an average of just over 91years old. This is unusual, but not impossible.
A hypothetical but possible reconstruction of the 365 years could be that Salmon crossed the Jordan as one of Joshua’s soldiers at 20 years old and given birth to Boaz 73 years later, at age 94, early in the judgeship of Ehud. Then Boaz married Ruth as an old man at age 96 and gave birth that same year to Obed in the judgeship of Deborah. Then Obed married and gave birth to Jesse at the old age of 98 during the judgeship of Jair. Then Jesse gave birth to David when he was 97. These numbers could be moved around somewhat with some men being a few years younger while other men would then be a few years older, for example, if one of the men got his wife pregnant when he was 115, then other men would not have had to have been as old to fill the time gap. The point is that the genealogy from Salmon to David that is recorded exactly the same way in four different books of the Bible can be the correct genealogy, and it makes more sense to believe what the Bible says in four different places than to doubt it simply because it seems unlikely.
“Perez was the father of Hezron.” The Hebrew uses an active verb, that Perez fathered Hezron.