Well we KNOW Christ was born 2007 years ago..
and we KNOW that the earth is only 6000 years old.. SOOOO it would have to have been in less then a couple hundred years.. I mean to go from 2 people to couple BILLION would take more than a few years I would guess..
And there is no way you can believe Adam and Eve were the ONLY humans on the planet at that time..
Do the math. N = No* e^(r*t) where No is the initial population and r is the rate of growth and t is the period of time in the same units as r. The mathematical constant e is the unique real number such that the value of the derivative (slope of the tangent line) of f(x) = e^x at the point x = 0 is exactly 1.
If:
No = 2
r = 1.17% = .0117 / year : current rates in countries in the world are between -1.20% and 4.84% with the global rate of 1.17%
t = 6000 years
N = 6.144727461286839e+30
Six billion is 6,000,000,000 = 6.0e+9
So you can start with 2 and get orders of magnitude more than 6 billion. Allowing for negative growth rates during wars, famines, and plagues and God wiping out the population of the earth with the flood and starting with 8 people, which everyone seemed to have missed, 6 billion seems reasonable starting with 2 over 6000 years.
Lets do it again and according to the Jewish historian Josephus, Irish archbishop and chronologist James Ussher, and most conservative Christian scholars, the Flood of Noah's time occurred between 2500 BC and 2300 BC, so lets use 2300 BC, for the shortest time period, and 2007 for a t of 4307 and a No of 8.
No = 8
r = 1.17% or .0117
t = 4307
N = 3.0689095874049684e+22
That is still orders of magnitude more than 6 billion.
And there folks is the reason that we better be very concerned about the future. Population growth looks like this.
<img src="http://www.grifent.com//pics/popgrow5.gif" />
Without a large scale war wiping out large portions of the world population or other major world wide catastrophe, the population will rapidly out pace the food supply and famine will be the limiting factor. And wonders of wonders, what does the Bible say about the last days and the cost of food?
Revelation 6:5-6
The Third Seal--Famine
5When He broke the third seal, I heard the third living creature saying, "Come " I looked, and behold, a black horse; and he who sat on it had a pair of scales in his hand.
6And I heard something like a voice in the center of the four living creatures saying, "A quart of wheat for a denarius, and three quarts of barley for a denarius; and do not damage the oil and the wine."
For those that don't know, a denarius is believed by scholars to have been a Roman soldier's daily pay. So the scripture is saying that enough wheat to make a small loaf of bread will cost a days wage. If you make barley loaves, you can get enough to make three loaves.