A very interesting read on this topic is Parasite Rex by Carl Zimmer. Fascinating life cycles that involve parasites and sometime multiple hosts. It seems having parasites is the norm.
I have two ways to think of it, and both give similar numbers.
A: 250 years ago, 98% worked in farming. Today it's 2% (who produce more food!). Assume that the other 2% are at least twice as productive, and you get that 3% of the population now produces as much as 100% back then.
B: It's hard to directly estimate how much GDP per person has increased in 250 years. But the typical number economists get when trying is that it's 30x as big. Which means 3.3% of today's workforce produces as much (per person) as the whole workforce did back then.
Both A and B can be critiqued, but the precise numbers don't really matter for the argument.
One of the books that got me introduced to this fascinating aspect of our natural world is John Tyler Bonner's Size and Cycle. It has features amazing log-log plots of how different organisms from grow with time: from eggs to full-grown organisms. This kind of visualisation gives you a different perspective on growth and scale
For example, Sequoia gigantea
Sequoia is the largest tree and can be effectively compared
to the annual plant shown above. Fertilization
and the early growth to the seed stage are essentially
similar, but because of the cambium and the possibility
of secondary thickening, the size of the tree can
increase enormously. As can be seen from Figure 1 in
the text, the sequoia does not begin to set seed until
it is sixty years old and eighty meters tall.
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