If I knew that by the year 2000 that there were 1 trillion humans, and that they started reproducing 2000 years before that, how would I calculate their birth rate?
Assume an initial population of 1 million, and a reproduction age of 15.
Also take into account a standard death rate, where death occurs after 75 years, and reproduction age ends at 50.
Update : Assume a uniform age distribution.