Question

1. If the number of your ancestors were to double every generation (30 years) going into the past, and the Earth's population were to halve every five generation going into the past, how long ago would these two quantities have been approximately equal, that is, how long ago would the number of your ancestors approximately equal the Earth's population at that time? Assume the current population of Earth is 8 billion. (Please note that before 1900, the Earth's population didn't increase as rapidly as assumed in this problem, but after 1900 it has been increasing more rapidly. Also, as the number of your ancestors increases, it becomes less likely that the number of your ancestors doubles each generation because they are duplicated. So there is some uncertainty in this calculation, but don't take that into account.) This would be one way to estimate the time in the past when the most recent joint ancestor of all humans alive today had lived.

Answer 1