Genesis Questions: The Ages of the Patriarchs

Adam lived for 930 years, his g-g-g-g-g-grandson Methuseleh (whom he lived to see) for 969, Noah for 950 years. After Noah, the average lifespan begins to slow down: his son son Shem only makes it to 600 then the lifespans begin falling in the 400s, 300s, 200s, until finally Abraham dies at a youthful 175 (probably dying before his own g-g-g-g-g-g-gfather Shem*).

For the moderate centenarians, the ages work perfectly if halved: we’re told that Abraham at 100 and Sarah at 90 welcomed Isaac long after they’d given up hope for a son, and that just a few years before Sarah was still being abducted into harems for her beauty, both of which are hard to believe, though it is possible to believe that a 50 year old and his 45 year old wife could have a surprise package child and that a woman in her mid or late 30s could still be beautiful enough to be abducted into a harem. (Similarly, using the half-dating Moses would have fled Egypt at 20 rather than 40 [killing an overseer in a huff seeming more like the act of a young man], returned- with his wife and very young children- at 40 rather than at 80, and then leading the Israelites for 20 more years.) However, nothing similar works for the “Ancient Ones”.

I’m not debating whether or not the people actually lived that long, but is there a reason given for why the life expectancy so rapidly diminished?

Does conservative Judaism believe in these ages?

Was there a purpose served mythologically by allowing characters to live for a millennium? (By Exodus Moses lives to a scant 120, and by the late O.T. life expectancies are about what we’d expect for the time.)

Also, one can see how the name Utnapishtim could be abbreviated or condensed into “Shem”. Is there any tradition that associates these two characters, both of whom lived to see their distant progeny centuries after the Flood?

Thanks for any info.

(These could be said to be GQs, but given the topic it will probably wind up in here anyway.)

*Genesis states that Abram’s father Terah was “more than 70” when Abraham was born but not how much over 70. Counting the year of Creation as 0 and going by the ages given for fatherhood and death, Shem was born in 1558 and died in 2158. Abraham would have been born sometime after 1948 and died sometime after 2123, giving a 35 year span for g-g-g-g-g-g-Grandpa Shem to survive him.

Two things: First, these are stories handed down for generations before they were ever written down. Many consider them to be just that – *stories * – and not history. The individuals could just as well be allegorical. Second, who says a “year” 'way back then consisted of the same 365+ 24-hour days? Suppose a “year” used to be, oh, 3 months long?

If you keep reading the Genesis, you’ll find your answer after The Flod.

On the second part the question becomes how many generations could the progenitor live to see? Even if a year were 3 months, assuming that the pregnancy term of humans was relatively constant (about 40 weeks) and that the onset of puberty was about 15 years, that’s 5 generations in 75 years. Some of the examples cited by the OP are 7-8 generations, or about 120 years, assuming that they bred as soon as physically capable.