Antonie van Leeuwenhoek and the lenses that changed our view of the world
By Caitrin Crudden
Scientists do science. Artists make art. Writers write. Right? You cannot get scientific credit without the long slog through a lengthy education, and dodging the daily struggles of academia. Or can you? What happens when contributions come from an “outsider”? What makes a scientist? And who decides?
In the 17th century, our view of the world was skewed in its proportions. We studied what we could see. In life science, anatomy was prevalent – beautifully detailed intricate depictions of the body, organs stacked upon organs in their intertwined functionality. But it stopped pretty abruptly where our vision blurred. However, another world lay in the abyss: a microscopic world. Perfectly unperturbed by observation, until one day, when a curious Dutchman dared to look. Antonie van Leeuwenhoek lived in the city of Delft, worked for the city council by day and ran a small haberdashery business. Believed to have originally stemmed from wanting to check the quality of thread for his business, he taught himself to make lenses. As it turned out, he was very good at it, and it was a pretty good time to be.
The Dutch had recently invented both the compound microscope and the telescope, and were leading the way in terms of natural exploration. Across the North Sea from van Leeuwenhoek, a prominent British scientist at the time, named Robert Hooke, had also begun to use microscopes to examine the tiny and was gaining fame from it. Hooke’s microscopes enlarged the world up to 50 times, and thus described in great detail insects, seeds and plants.
Van Leeuwenhoek’s could achieve a mind-bending 270 times magnification; hence, his eyes were the first to truly peer into the microscopic world. Most importantly, van Leeuwenhoek was curious. He was skilled, careful, and he was curious. He took samples of pond water and began scrutinizing their contents: a microscopic dance unfolded before his eyes. He discovered that a single drop of pond water was packed with unicellular organisms many times smaller than the width of a human hair. On the animal side – protozoa, a diverse group consisting of single-cell organisms capable of “animal-like” behaviours such as movement and predation. And their plant counterparts, such as single-celled algal spirogyra, which differ from protozoa because they have the capacity for photosynthesis. Van Leeuwenhoek scraped his teeth first thing in the morning and inspected the brigade of life housed inside him, and even sought out men who had never brushed their teeth in their life for comparison. Modern estimates suggest there are 500-1000 different types of bacteria in the average human mouth. In contrast to our long-held pathogenic beliefs, the vast majority of them are beneficial to our health and important for the maintenance of an active immune system. To add to his long, long list of firsts, he discovered differentiated red blood cells in blood samples and studied their flow in the capillary system. Perhaps most notably, he described, for the first time, spermatozoa in humans and other animals, making the connection that spermatozoa fertilized the egg, and in doing so, broke open the missing link in the inheritance puzzle. He replicated his studies with precision, and meticulously noted and drew what he saw. Since nobody had even imagined there would be life at this level, let alone categorized it, this pioneer affectionately named what he saw “Animalcules” (literally little animals). It is worth taking a moment to pause and appreciate the gravity of these findings. At that time, the prevailing hypothesis was “spontaneous generation” – that life could develop from non-living matter, for example, maggots on rotting food. The existence of life forms beyond our visual perception changed everything; life science literally had to be re-written. And for years, a working-class Dutchman with no formal scientific training was the only one to have ever laid eyes on this microscopic wonder-world.
Van Leeuwenhoek’s contribution is as significant as it is undocumented. Now dubbed by some “The Father of Microbiology”, van Leeuwenhoek never published any scientific articles or books. His contributions are largely known through correspondence with the Royal Society, the prestigious British scientific institution, whom he believed should be aware of what he found. Over his life, he sent hundreds of letters full of sketches, colloquial Dutch and charming ramblings of local news and reports of his own health. The Royal Society, although initially intrigued, grew suspicious of this unknown man and questioned his credibility. Robert Hooke, the currently proclaimed expert on microscopy, attempted to replicate these findings, but given his inferior tools, he failed. Van Leeuwenhoek’s descriptions of single-cell organisms were met with widespread scepticism, and these seemingly outlandish ideas ruffled the feathers of the ivory tower. Science was a prestigious pursuit – a pursuit reserved for men of high standing and high education.
Thorough investigation, including numerous Society members travelling to Delft to verify the content of van Leeuwenhoek’s letters, would ultimately require the Royal Society to rewrite its scientific belief system. In 1680, van Leeuwenhoek was elected to the Royal Society on the nomination of William Croone, a renowned British physician. The Society broke its own rules by writing the diploma of membership in Dutch since van Leeuwenhoek could not read Latin or English. He did not attend the induction ceremony, nor did he ever attend a Royal Society meeting, he simply continued as he always had – studying the small and writing letters. After he died, van Leeuwenhoek left a cabinet of his belongings to the Royal Society, containing his microscopes and mounted specimens. A would-be treasure to the scientific world, the cabinet disappeared and has never been found. Another century would pass before technology would catch up to van Leeuwenhoek, and his pioneering genius would be confirmed and appreciated.
So it leaves us to ponder: what makes a scientist? A list of university degrees and affiliations? Peer-reviewed scientific publications? Membership in exclusive clubs and societies? Or is it something much more fundamental – a natural curiosity? In a world of clubs, ivory towers and membership societies, many of which are as impenetrable as any privilege, who is being excluded? How much is the world missing out on? Antonie van Leeuwenhoek embodies everything it means to be a scientist, albeit without any ceremony or certificate or badge endowing him the title. Unencumbered by the paradigms of the time, he dared to look where nobody had looked before. He was methodical in his observations, repetitions, recording and communication. A tradesman, from a family of working class tradesmen. An unlikely scientist. But a scientist nonetheless.
“My work, which I’ve done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men.”
— in a letter dated 12 June 1716
“Whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof.”