How is it possible that the people of Israel reproduced so greatly in Egypt within a period of just 210 years?
Let us recall that the Tora explicitly indicates just two things:
1- The number of Jewish men who arrived to Egypt was 70.
2- When they left Egypt, there were 600,000 men between the ages of 20 and 60 years old. Including the women, children and elderly we assume a number of approximately 3 million.
THE MORE COMPLEX RESPONSE
Rabbi Shemuel David Luzzatto (1800-1865) formulated a couple of ideas that, although not far from the peshat– that is, the literal meaning of the biblical text- are still a little bit controversial. He says that based on one explicit verse, Jews were in Egypt not for 210 years, but for 430 years (Shemot 12:40). He also states that when the Tora speaks of the generations that have passed since the jews arrived to Egypt (too few to cover more than 400 years) the text does not refer to “father > son” rather, “patriarch > descendants” (this article in Hebrew explains in more detail the opinion of Rabbi Luzzatto) .
THE SAGES’ RESPONSE
Rabbi Luzzatto’s position might have a textual merit, but let us first explore the feasibility of what our Sages themselves state: the amount of time that the Jews spent in Egypt was indeed 210 years (116 of which they had spent in slavery).
Our Sages, who also inquire as to how 70 families became 600,000, explain that Jewish women would birth to up to “6 children at a time” (bekeres echad). Yet I believe that we don’t even need to resort to the case of multiple sextuples to explain the increase in numbers.
THE EFFECTS OF MARRYING YOUNG
The most essential thing to understand is that 210 years could cover up to 10 generations- when taking into account that Jews, who have always practiced premarital abstinence, generally marry young. Until today, most observant Jews marry on average by 21-24 years of age. If 70 men arrived in Israel (with their wives) and each couple had, say a total of 6 children, in 6 generations will count: 3,265,920 (70 x 6 x 6 x 6 x 6 x 6 x 6).
We have an explicit example of a family of 6 generations in the case of Yehuda. Yehuda came down to Egypt and Nachson left Egypt, six generations later. Yehuda> Peretz> Hetsron> Ram> Aminadab> Nahshon. And Nahshon probably already had his own children when he left Egypt. Dibre haYamim I (7:22) counts 9 generations from Efrayim, the son of Yosef, to Yehoshua bin Nun.
RABBI ELYASHIV RESPONSE
I believe that the best way to grasp the realism of these Biblical numbers and the Rabbis’ opinions comes from the life of Rabbi Yosef Shalom Elyashiv z”l. This prestigious contemporary rabbi was the only child born to his parents after 17 years of marriage. He was born in 1910 and died in 2012. He reached a privileged age of 102 years.
Now, how many descendants did Rabbi Elyashiv left in this world when he passed away?
He had 12 children. And according to Wikipedia at the time of his death he had about 1,400 descendants, over 6 generations (See here). The secret? 1. His children, grandchildren, great-grandchildren and great-great-grandchildren also had a significant number of children (probably an average of 8 children) and 2. They married relatively young.
