From the ICR’s URCall series of videos, hosted by Markus Lloyd. “How did we reach 7 Billion people?” (link)
How can we have a world population increase to over seven billion people today from only eight survivors from Noah’s flood, if the Earth is only a few thousand years old? Let’s assume one male and one female marry, and had children, and all their children marry and had children, and so on. Let’s assume, conservatively, that every 150 years the population doubles. After 32 doublings, or 4800 years, the population would reach almost 8.6 billion – which is more than we have now. On the other hand, if modern humans started 50000 years ago, at the same conservative population growth rate, even considering death rates, famine, wars etc, all the people could not even fit on the Earth. So if humans had really been around for millions of years, where did everybody go?
Let’s take a look at the equations. The ICR’s gloriously simplistic model can be written like this.
Or, if you prefer symbols:
If you read through the numbers given by Lloyd you’ll see that the ICR is saying that, under their YEC scenario:
The numbers technically check out, but note that they use a starting population of 2, rather than 6 (Noah’s children and their wives – Noah and his wife don’t count because they already had children). In addition, 4800 years is not a typically quoted amount of time since the flood: it seems to have been chosen only to make the numbers clean. More common figures that I have seen range between 2000 and 2500 BC (4000 – 4500 years ago), but we’re only talking about a world changing even that affected the entire globe – we can’t expect them to have any idea when it happened, can we?
It should be obvious that the numbers are quite malleable: if their holy book told them that it happened more like 2000 years ago, all they would have to do would be to drop their “conservative” 150 years per doubling down to around 50, and replace that two with the more biblically accurate six. But the question they were answering – if anyone was asking – was if it was possible to reach 7 billion from just eight (or six). And if you ignore the fact that the second generation would have to commit incest, along with various other problems, it works.
But then they try to turn this around and attack people who don’t believe in a young Earth, which is pretty silly.
Substituting 50000 in instead of 4800 the answer comes out at about four and a half googol – which is comfortably more than there are atoms in the universe, let alone places for them to stand. The situation is reminiscent of a 1962 short story by Frederik Pohl called The Deadly Mission of Phineas Snodgrass, in which the titular character brings 20th century medicine back to 1st century Rome, and we follow what happens from there.
By the middle of the sixth century the 600,000,000 square miles of land surface on the Earth were so well covered that no human being standing anywhere on dry land could stretch out his arms in any direction without touching another human being standing beside him.
(100 Great Science Fiction Short Short Stories, 1978, page 63. I’ll not spoil the ending for you, but it goes on like that for another page.)
But if the population is always just doubling in a certain number of years, why would giving Romans medicine change anything? The answer of course is that the ICR’s model has very little bearing on reality. If there are too many people than the Earth can support then there will be no more people – and for a lot of the last 50000 years the number of people that could be fed was quite small. We only made 7 billion because of modern farming technologies, and of course modern medicine.
A case in point: bacteria are much smaller than us, but they can double their population much faster. Given a doubling time of, say, 2 hours it’s not hard to calculate that they could overrun us in less than a month. I can’t prove that the Earth is older than this – just as you can’t prove it wasn’t created last Thursday – but if it is, “where did everybody go?”