[p]There was some discussion in my thread on macroevolution, as to whether 4,000 years was a sufficient amount of time for 125 billion people to have been born and died (or still alive). I thought I would lay out what I thought was the easiest way to try to answer the question:[/p] Assumption #1: There were 8 founders. Assumption #2: A consistent generation time of 25 years. Assumption #3: The sex ratio is 50/50. Assumption #4: Everybody has three children. [p]Based upon the above assumption, every couple would have three children. This would mean that the population increases by 1.5 every single generation, as follows:[/p] [TABLE] width="500" style="width: 500px" |- | Generation(years) | Population |- | 0(0) | 8 |- | 1(25) | 12 |- | 2(50) | 18 |- | 3(75) | 27 |- | 4(100) | 40.55 |- | 5(125) | 60.75 |- | ........................... | ........................... |- | 160(4,000) | 1.195890555 x 10^29 |- [/TABLE] I'm no mathematician, so I don't know what the 1.1958..... number actually works out to be. I don't have a special formula since I can't figure out any pattern to the 1.5ing every generation (can anybody help?). But if we could get a nice formula, then we could tweak each variable to make it more realistic, and hence give a more accurate figure. However, we would also need to take into account death by disease, wars, murder etc. I don't know how you would do that, but perhaps we could get around it by assuming the slowest growth rate possible. If it is still possible to get 125 billion people in 4,000 years with a much slower birth rate than 1.5, then it becomes quite probable that it could actually happen. Thoughts?