Bereshit 5:3 records that Adam had a child when he was 130 years old, something that is not possible in the 21st century. 5:4 then records that Adam lived another 800 years afterwards. This also is not physically possible. The remainder of chapter 5 lists ten more individuals who also lived extremely long lives. Similarly, 11:10-32 lists nine more individuals who had extremely long lives. The people listed in chapter 11 lived less years than all the people listed in chapter five, except for Chanoch (5:23), but still eight of them lived more than 200 years, which again does not seem possible. Afterwards the lifespans continued to decrease, but still the Torah lists many people who lived longer than humanely possible in the 21st century, Sara, 127 years (23:1), Avraham, 175 years (25:7), Yishmael, 137 years (25:17), Yitzhak, 180 years (35:28), Yaakov, 147 years (47:9, 48:28), Levi and his descendants’, 137 years, 133 years and 137 years, (Shemot 6:16-20), Aharon, 123 years (Bemidbar 33:39) and Moshe lived 120 years (Devarim 31:2). Yosef also lived 110 years (Bereshit 50:26), which also seems incredible for the period of the Torah.
The Rambam (Moreh 11:47) writes, apparently in reference to all the people who had long lives in the Torah, that only these people lived so long, as the other people who are not named as having long lives, lived regular lives. The Rambam suggests that the long lives of these individuals could have been due to their diet and behavior or due to a miracle. The Ramban (on 5:4) rejects this approach and claims that the people listed in chapters five and eleven were not unique in their lifetime. He notes that if the Rambam’s suggestion of diet and behavior was correct, then many people should have followed their behavior. Also, he claims that not all of these people were worthy of G-d making them miracles. It seems to me that even the Ramban relies on miracles for the long lives of the patriarchs. The Ramban also seems to claim that until the period of the sin of the Tower of Bavel people would naturally live long lives, which again appears to be impossible.
A different approach is that the years listed in the Torah are not full solar years. Ha-Ketav Ve-haKabbalh (on 5:5) notes that some people claim that the years in chapter five are based on a one-month lunar cycle which he rejects. Beck (1967, pp. 25-29) suggests that a year in the Torah is a six-month period, and then the lives of the patriarchs would be half of what is recorded in the Torah.
My guess is that the years in the Torah are similar to our years, that the Rambam is correct that only those people who are listed as having had a long life, had a long life and that this was a miracle that G-d did for them. It is not clear why it was necessary for these people to have long lives, and my guess is that it is a literary way of marking a large passage of time with a relatively limited number of people.
In addition, with regard to the people who had long lives, it must be that their aging process was a much slower process than our aging in the 21st century. David Tzvi Hoffmann (1969, p. 383, introduction to chapter 25) follows this idea when discussing how old was Avraham when he had more children apparently after Sara had died, 25:2. He writes that even though Avraham was officially 140 then (if these children were born right after Yitzhak married Rivka), he was really 56 years ago. This calculation would be that 140/175, his present age divided by the age when he died, equals 0.8 and 0.8*70 = 56. Thus, he claims Avraham was able to father the children recorded in 25:2. While I think Avraham had the ability to father the children recorded in 25:2 due to a special blessing from G-d (see our discussion on 24:1, “To be virile again”), it must be that Hoffmann is correct that the aging process for the people who had very long lives in the Torah was at a proportional rate.
I think that even by the early years of the people who had long lives in the Torah that their development was at a slow pace, and then they reached puberty later than modern people. Thus, the youngest age that people in chapter five began to have children was 65. In chapter 11, the aging process had quickened to some extent compared to the people in chapter five, as the youngest age that people had children in chapter 11 was twenty-nine years (11:24), and their life span had shortened from between 400 years to 148 years, but still their aging was slower than people in modern times. Afterwards by the age of the patriarchs until, and including, Moshe, the development and aging of the people with long lives were proportional to a person who lived seventy/ eighty years.
Thus, Sara was considered beautiful when she came to Egypt (12:11,15), even though she was sixty-five years old, since she had not yet aged that much because she was going to live until 127, 23:1. Hence, she was around 35 years old based on a lifespan of seventy years. This slower proportional aging is also why the Torah had to tell us that Sara had stopped menstruating when she was 89/90, 18:11, which should have been obvious, but with proportional aging, one might have thought that at 89/90 (17:17), which was proportional to 49 years ((89/127)*70), that she was still menstruating, but she was not.
Avraham was equivalent physically to a 30-year-old ((75/175)*70) when he left Haran and fought with the four kings and not to a seventy-five year old (12:4), which in antiquity and today was/is possible, but it is very unlikely for a seventy five year old to have the strength to fight a war. In addition, Sara thought that there was a good possibility that Avraham would be able to have a child with Hagar even though he was 85 years old then, since if it was not possible, she would not have been willing for him to have another wife, 16:1-3. Also, Avraham agreed to her proposal and did not claim that he could not have a child when he was 85 since really he was physically around 34 years old (86/175)*70).
14 years later, when Avraham was officially 99 years old, both Avraham and Sara doubted whether Avraham could father another child, 17:17,24; 18:10,12; 21:1-7. 18:11 (also 21:2), which is information provided by the “narrator” records that Avraham and Sara were old when they were told that Sara was to have a child, but also adds the phrase “and advancing in years.” This phrase is qualifying the previous word, that they were old, that while they were getting older, they were not necessarily not “functioning” and then the verse continues to inform us that Sara was post-menopausal since, as mentioned above, this was not obvious. Yet, according to this theory of proportionate aging, Avraham was then equivalent to being 40 years old (99/175)*70), so why did Sara and Avraham doubt that he could have a child? Maybe Avram and Sara were considered old even in their 40s, since in those days, life expectancy was around 40, even for people who did not die at childhood. In addition, maybe Avraham’s and Sara’s doubt that Avraham could have a child just “six years” after fathering Yishmael was because they did not think that a person at Avraham’s age (physically equivalent to 40 years) would be able to recover sufficiently from the circumcision, which G-d had just commanded him to do, 17:10-14, and he had done, 17:23,24, to have a child. Maybe then, Avraham’s ability to have Yitzhak was due to a miracle.
This idea of proportionate aging could also explain why Yishmael seems to have been small when he and Hagar had to leave Avraham’s house, even though he was 14-years-old, 21:14-20. Also, while Yishmael was officially 13 years old when he was circumcised this would have been equivalent to being six and a half (17:25; 25:17 (13/137)*70).
Also, with this understanding, Yosef was not mentally or physically 17 years old (37:2) when he tattled on his brothers, but around 12 years in modern terms, and he was equivalent to an 18-year-old ((28/110)*70) when Potifar’s wife tried to seduce him, 39:7-12. This might explain why Reuven also refers to him as the child, 37:30 and 42:20. This would also mean that when Yaakov sent Yosef to look for his brothers in Shekhem, 37:13, Yosef was equivalent to a ten-year old in modern times, which might be considered as being too young for such a mission. However, as we explain in our discussion on 37:3-14, “Yaakov's parenting,” Yaakov accepted that the dreams of Yosef were a prophecy, and hence he probably felt that Yosef would be protected.
This slow aging process might also help explain the conversation between Pharaoh and Yaakov when they met, 47:8,9. First, Pharaoh asked Yaakov how old he was since he knew that Yosef was not aging in the normal manner. Secondly, this proportional aging can explain why Yaakov knew that he would not reach the lives of his father and grandfather since he knew at 130 years that he was aging faster than they had been aging at the same age, 47:9.
The net result is that since the long lifespans recorded in the Torah of various people was a miracle, the miracle was also that the development and the aging process of the different people were also a slower process than in modern times, and starting in the time of the patriarchs, the development and aging process of the people with long lives was proportional to the lifespan of each person.
Bibliography:
Beck, Samuel, 1967, From Sinai to Navo, Jerusalem: Raphael Chayyim Hacohen Publishing.
Hoffmann, David Tzvi (1843-1921), 1969, Commentary on Genesis, Bnei Brak: Nezach.