How could people live so long at that time?
The average age of the patriarchs mentioned in Genesis 5 is 912 years. Several factors doubtless contributed to this amazing phenomenon.
A. As a slow-developing cancer will often take several years to destroy a healthy body, so the physical results of sin settled down upon the bodies of men.
B. Prior to the Flood, there apparently existed many times more water vapor in the upper atmosphere than there is today. (Cp. Gen 1:7 with 7:11.) This vapor, although invisible to the eye, would nevertheless function as a filtering protection and shield against the amount of intense radiation falling upon the earth from the sun. Scientific research is now demonstrating that radiation can appreciably reduce the life span of living tissue and actually cause the cells to speed up the process. Of course, after the Flood that protective watery canopy disappeared as it fell upon the earth in the form of rain.
