Replacing 8 Flood Survivors with 8 Billion!
Dr. James J. S. Johnson
And God blessed Noah and his sons, and said unto them, Be fruitful, and multiply, and replenish the earth.. … And you, be ye fruitful, and multiply; bring forth abundantly in the earth, and multiply therein.
Genesis 9:1 & 9:7
Sometimes scoffers disparage the Genesis history of the global Flood, by saying “there isn’t enough time for Earth to repopulate” to its present population of about 8 billion.1
Human lifespans are all-too-often taken for granted, yet the total number of human generations is not that many—because less than 200 successive generations have occurred since Noah’s Ark was vacated.
However, Earth now houses 8,000,000,000+ people, derived from only eight—so each Ark-borne human is now represented by a billion people! Does that make mathematical and historical sense?2 As shown below, both the Scriptures and the math say “yes!”
To appreciate how, consider that today’s 8,000,000,000+ humans derive from just 3 reproducing couples—Shem, Ham, Japheth, and their respective 3 wives—who survived the worldwide Flood, about 4500 years ago.
HOW MANY GENERATIONS WERE BORN AFTER THE FLOOD?
How many generations, on average, have occurred during the 4,500 post-Flood years? That depends on what the age of a birthing mother is—comprehensively averaged over the past 4500 years. During those 4½ centuries, were human mothers giving birth—on average3 (since many mothers have more than one child)—when about 25 years old, or maybe when 33⅓ years old?
If 25 years defines a generation, that averages 4 generations per 100 years. However, if 33⅓ years defines a generation, that averages 3 generations per 100 years.
Consequently, if the average “generation” is 25 years, 4500 years is composed (using averages) of 180 post-Flood generations. Likewise, if the average “generation” is 33⅓ years, 4500 years represents (using averages) only 135 post-Flood generations.
TO POPULATE TODAY’S WORLD, WHAT REPLACEMENT RATE IS NEEDED?
A population “replacement rate” is the ratio of the population in a filial (i.e., children’s) generation compared to its parental population who procreated them. In other words, how many people within a filial generation replaced those who were in the prior (i.e., their parents’) generation?4
For example, consider a modest population replacement rate of 1.2, i.e., as the average ratio of filial population to parental population, over 4500 years.
Defining a generation at 25 years, 6 reproducing adults produce one quadrillion descendants in the 180th generation, because 6 X 1.2180 = 1.0734 quadrillion. However, defining a generation at 33⅓ years, 6 reproducing adults produce almost 300 billion descendants in the 135th generation, because 6 X 1.2135 = 293.5 billion. Obviously, Earth’s current population is not due to an average replacement rate of 1.2 (or higher)!
Next, consider a modest population replacement rate of 1.15, i.e., for every individual in a parental generation there is (on average) 1.15 in the next generation.
Defining a generation at 25 years, 6 reproducing adults produce a half-quadrillion descendants (too much!) in the 180th generation, because 6 X 1.15180 = 505 trillion.
However, defining a generation at 33⅓ years, 6 reproducing adults produce less than a billion descendants (too few!) in the 135th generation, because 6 X 1.15135 = 0.938 billion.
Accordingly, Earth’s current population came from between those 2 averages.
Therefore, if Earth’s current population was produced from average “generations” somewhere (historically) between 25 and 33⅓ years (for childbearing), a modest population replacement rate near 1.15 is about right.
Such a modest rate of population increase yields no excuse5 for scoffers to reject Genesis, by claiming that “there isn’t enough time for Earth to repopulate” to its present population of about 8 billion, restarting from 8 about 4500 years ago.
REFERENCES
1.Christ admonished that disagreeing with Genesis is foolish (John 5:44-47).
2.”[Pre-Flood humans] were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was being prepared, wherein few, that is, eight souls were saved by water.” (1st Peter 3:20)
3.Historical averages are counted here, because some women procreate no children, while others bear one or more children.
4. If one couple (i.e., 2 parents) procreated 2 children, the replacement rate is 1, because the 2-to-2 ratio equals 2 divided by 2. However, if one couple (i.e., 2 parents) procreated 4 children, the replacement rate is 2, because the 4-to-2 ratio equals 4 divided by 2.
5.Evolutionists imagine 100,000s of age for humanity — this is a ridiculously inflated number, so it doesn’t “count”.
Pine Jays, Providence, Plus 