I received the following question:

Question. Read your article on Right Division in Genesis in the Bulletin. You seem to equate the drop in age after the flood to genetics. I thought it was because of the destruction of a canopy over the earth.

It may be a simplification to say that the drop in age was due to any one cause. Clearly, something changed at the time of the flood. Ages were not dropping before that time in any detectable way at all. After the flood, they dropped rapidly. I have heard various ideas as to why this was, and the one that makes the most sense to me is genetics. Intermarrying with only 8 people (really 5, since you had Noah, his wife, and his three son’s wives; his three sons all shared Noah and his wife’s genes) resulted in a rapid drop in ages.

As for the canopy, that is an interesting idea that a lot of creationists have. I am not entirely convinced that it is true. I am not convinced it is not. I guess I am simply undecided. But the arguments for a canopy disappearing do not convince me that this would really cause the drop in ages. If higher air pressure is the cause, then why don’t people who live at lower elevations live longer than those who live at higher elevations? Same thing for UV radiation being blocked by a canopy (the atmosphere also blocks radiation). I am just not convinced that this would be the case. Of course, if there was higher oxygen content in the air before the flood due to higher pressurization, that could make a difference. But why didn’t the ages drop all at once, then? Why did they slowly change from generation to generation? I still go back to genetics as the most likely explanation.

Of course, the Bible doesn’t say why, so ultimately all we can do is speculate.