In article <793029244snz at price.demon.co.uk> price at price.demon.co.uk writes:
>"John de Rivaz" writes:
>> I have been asked for the reference to the oft-quoted "if all
>> those who have ever died were resurrected the world's population
>> would only double."
>>>> Flicking through my books, including Jack Parsons' "Population
>> versus Liberty" has not produce it.
>>It's been years, but I remember some such quote from the opening of an
>Arthur C Clarke book, 2001 (I think).
>He says something like "behind every person alive today there stands 20
>[not 1] ghosts". Now I know 2001 is fiction but Clarke usually gets his
>non-speculative technical details correct.
>>Michael Price price at price.demon.co.uk
Well, folks, it simply depends on who we're talking about. If we
recognize our descent from the first eucaryote, then we'd have to
count perhaps a trillion direct ancestors. Or you could stop at
animals, vertebrates, mammals, or primates, in which case the numbers
would sharply drop.