Population, Leeuwenhoek and National Geographic

National Geographic is running a special series on population – and who is leading the way on population estimates?

Though his tiny peephole gave him privileged access to a never-before-seen microscopic universe, he spent an enormous amount of time looking at spermatozoa, as they’re now called. Oddly enough, it was the milt he squeezed from a cod one day that inspired him to estimate, almost casually, just how many people might live on Earth. Nobody then really had any idea; there were few censuses. Leeuwenhoek started with an estimate that around a million people lived in Holland. Using maps and a little spherical geometry, he calculated that the inhabited land area of the planet was 13,385 times as large as Holland. It was hard to imagine the whole planet being as densely peopled as Holland, which seemed crowded even then. Thus, Leeuwenhoek concluded triumphantly, there couldn’t be more than 13.385 billion people on Earth—a small number indeed compared with the 150 billion sperm cells of a single codfish!

Not very accurate, but he was the first to consider our planet’s population.

Read 7 Billion for more on Leeuwenhoek and population at National Geographic.

Leeuwenhoek and the World’s Population

The History of Science Centre’s blog at the Royal Society has an article on what is perhaps the first attempt to estimate the human population of the world:

Leeuwenhoek wrote: “If we assume that the inhabited part of the earth is as densely populated as Holland [which then had a population of perhaps one million people]… the inhabited earth being 13,385 times larger than Holland yields . . . 13,385,000,000 human beings on the earth” In the 20^th century much larger and much smaller estimates of how many people the Earth can support were offered, Cohen remarked – all of them based, like Leeuwenhoek’s, on incomplete data and questionable assumptions.

Read the complete article at The twelve billion lives of Antoni van Leeuwenhoek