Human sperm is very different from anything else in the body. It is the only type of human cell designed to move outside the body to fulfill its purpose. And yet the science of these cells lags behind other studies of the human body. That research had a pretty rocky start. Anton van Leeuwenhoek developed the compound microscope, and was the first to observe live sperm through it in 1677.
Examining his own ejaculate, he was immediately struck by the tiny “animalcules” he found wriggling inside.
Hesitant to even share his findings with colleagues—let alone get a wriggler tattooed on his arm—van Leeuwenhoek hesitantly wrote to the Royal Society of London about his discovery in 1677. “If your Lordship should consider that these observations may disgust or scandalise the learned, I earnestly beg your Lordship to regard them as private and to publish or destroy them as your Lordship sees fit.”
His Lordship (aka the president of the Royal Society) did opt to publish van Leeuwenhoek’s findings in the journal Philosophical Transactions in 1678—thus begetting the brand new field of sperm biology.
It’s hard to overstate how mysterious these squirming, microscopic commas would have appeared to scientists at the time. Before the discovery of these “animalcules,” theories of how humans made more humans ranged widely, says Bob Montgomerie, a biologist who studies animal reproduction at Queen’s University in Canada. For example, some believed that vapor emitted by male ejaculate somehow stimulated females to make babies, while others believed that men actually made babies and transferred them to females for incubation.
It would take another 200 years for scientists to figure out how babies were made, exactly. But sperm research has continued, and yet there is so much we still don't know. Cracking the code of what sperm is made of and how it behaves will pave the way for a male contraceptive someday. Maybe. Read the story of sperm research at Smithsonian. There, the reference to the "wriggler tattooed on his arm" will be made clear.