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.

Top Ten Zoological Discoveries

The Guardian has an article on the greatest discoveries in zoology:

At BBC Wildlife magazine, a panel of judges has been mulling over the question. Today, the results of their deliberations are published as the top 10 breakthroughs in zoology. The list in full is below, in descending order. How have they fared?

Leeuwenhoek places second, just below the discovery of the fossilised remains of Archaeopteryx:

The 17th century Dutch scientist Antonie Philips van Leeuwenhoek made some of the best microscopes of his time, using them to discover microorganisms, or “animalcules”. His work led to dramatic re-evaluations of the causes of disease and improvements in hygiene.

Read the complete article at the Guardian, and visit BBC Wildlife for the source.

Look out for We, Beasties…

A new blog called We, Beasties is joining ScienceBlogs. It is run by Kevin Bonham who is in the immunology program at Harvard. He and other contributors will be covering the diverse world of microbes, and he pays tribute to Leeuwenhoek in his first post today:

In 1674, Antonie van Leeuwenhoek pointed a microscope at pond water and saw what he called “wee beasties” flitting about, kicking off the field of microbiology. Since then, scientists have discovered microorganisms living just about everywhere, in every kind of environment, from the crushing depths of the ocean in hydrothermal vents to the crypts of our own intestines.

Go to We, Beasties for more on microbes.

London Dreaming…

The Linnean Society, The Royal Geographic Society, The Royal Geological Society, The Natural History Museum…

The Royal Society is hosting a series of free lunch time lectures on the history of science. On October 29 at 1:00 PM they are featuring Professor Brian J. Ford, an expert on the history of microscopy:

The birth of microscopy is here shown to be very different from the traditional view. Standard texts inform us that pioneers, like Hooke, used compound microscopes to investigate the microscopic world. Yet there is a paradox: the fine images in works like Hooke’s Micrographia (1665) include details that contemporaneous compound microscopes could not resolve.

The single lensed (=simple) microscope has been dismissed as a crude instrument of limited capacity, and recent demonstrations on television have confirmed this view. Today we shall discover that remarkably clear images were obtained by lenses of diminutive size (often no larger than the head of a pin). The work of Hooke, Leeuwenhoek and Robert Brown is re-examined, and their remarkable results are now reconciled with the technical capacity of the instruments they used in their investigations.

See the Royal Society Events Diary for more on the lunchtime  lectures.

Wish I could be there…

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 20th 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

First Published Microscopy Article?

Before Hooke published his Micrographia (1665), and before Leeuwenhoek’s first letter to the Royal Society (1673), others had published on microscopy. The OU History of Science Collections has documented two more early users of the microscope. They were contemporaries of Galileo  – fellow members of the Academy of the Lynx-Eyed – and they produced a document called the Apiarium:

The Apiarium (Rome, 1625) was a gift of the Lynx to the new pope. Galileo adapted the telescope into a new instrument, named a microscope by a member of the Lynx. In the Apiarium, the first publication of observations made with a microscope, Federico Cesi (1585-1630) and Francesco Stelluti (1577-1651) studied the anatomy of the bee.

Learn more about this document and find further links in the article: Earliest published microscopic study.

(Image from OU History of Science: Apiarium)