[kragen]

agriculture is the reason there were 2 billion instead of 20 million, which is a much bigger difference

it seems likely that digital technology will be crucial in enabling there to be far more humans off earth than on earth; o'neill cylinders could enable many orders of magnitude more physical humans even within this solar system

to say nothing of the possibility of backing up your mind with a brain scan and thus becoming immortal, and possibly forking into more copies of your mind than there are humans alive today

(nitpick, transistors aren't digital)