Elderly Male Fertility

The Torah, in Parhas Vayera, suggests a curious biological fact, or poses for today’s medicine a good question: Our matriarch Sarah laughed at the thought of having a baby at 90 years old, because “long after my menopause shall I be rejuvenated? And, (besides) my husband is old.” (Gen.18:12)

ותצחק שרה בקרבה לאמר אחרי בלתי היתה לי עדנה ואדני זקן

The last clause, “and my husband is old”, would make no sense to today’s medical profession. True, women need their periods to be fertile, but men, so what if they’re old? After all, their fertility apparatus can well function no matter what the age.

But the Bible here suggests otherwise; Perhaps sperm of older men lose their fertility “index”, or perhaps their motility index.

Personally I never heard of deterioration of sperm with age -- although it sure sounds plausible, especially because that's what Torah here suggests!

Some might suggest testosterone levels are involved and, usually those who know the least will quickly point to “genetic” causes, but if the hypothesis is true it would have to be proven and not just conjectured upon.

It’d be interesting to find out.

Now if having children at 100 is miraculous, then of course is the miracle of having them at age 140, when Abraham again married and had 6 more (gentile) children.

Of course these aren’t separate miracles but a generation-long extended one, for the miracle of Yitschok’s birth extended it to the entire locality or generation (A “happy generation” -- as Yitschok’s name suggests), for all barren women, gentiles included, became fertile, and apparently age then did not render the old male infertile.