Two people reproduced 7 billion people.

[John V]

Two words eople die.

Six words: each line is a separate generation.

For example, the second line is nine. That's 3+3+3, the three surviving children of each of the three initial couples. The parents are not included in that number. We're accounting for death.

Three children per couple seems reasonable, but let's lower it. Set the growth to just 10%. Now you hit 7 billion in the 293rd generation. If a generation is 20 years, that's 5,860 years, and we're not even building in the effect of the early long life spans.

It just doesn't take that long.