[boatbums]

(If Genesis is to be believed, then we all sprang from incestuous relationships, the children of Adam and Eve had to marry and mate one another.)

I don't see any reason why Genesis should NOT be believed. Don't forget, these first humans lived hundred of years and we don't know how long they remained in childbearing condition. If you look at cats, for example:

Eighty million cats is a lot of cats. However, you would be surprised how quickly two cats can become that 80 million. If you let two cats breed at will — and then allow their offspring to breed at will, these two cats will have 80 million progeny within a decade! This assumes two litters per year and 2.8 surviving kittens per litter. Here are the numbers:

First year: 12

Second year: 66

Third year: 382

Fourth year: 2,201

Fifth year: 12,680

http://www.care2.com/greenliving/how-long-does-it-take-2-cats-to-turn-into-80-million.html/2

Granted, humans aren't cats and they don't have "litters", though we hear of women giving birth to multiples all the time. Plus, a cat's lifespan is 15 - 20 years AT BEST. It's only around 5 for feral cats these days. For humans who lived for hundreds of generations it's not unfeasible that a man might mate with a distant relative and it not BE incest at all.

[Cvengr]

2 additional points.

1) For a proper study of human growth rates, we only have to study that documented for Israel during the Exodus.

Reverse calculations of the growth rates give an age closer to the dates documented in Scripture than the billions and billions of years commonly assumed.

2) The first generation after the flood is a unique generation, in that the parents outlived their grandchildren. Rmember how the first generations didn’t just live 72 some odd years, but for a thousand plus years. It is very likely that many stories were spread amongst their remnant of ancient history, which were then carried into other bloodlines and then future lineages.

[verga]

Your numbers are correct up to a point. Cats reach maturation between 1 year and 18 months of age and can begin producing offspring immediately. Humans take much longer to reach maturation and a single offspring per year is the norm.

At that rate you would be looking at somewhere between 8-12 thousand years. Still well within the realm of possibility when you factor in variables such as war, pestilence, disease, natural disaster, etc....

Excellent research!

[Boogieman]

“though we hear of women giving birth to multiples all the time...”

Not to invalidate your main point, but this is mainly due to the rise of fertility treatments. It’s still very rare to have multiple births through natural conception.