In the 17th century, physician and chemist Jean Baptiste van Helmont, apparently sick of there not being enough mice in this world, devised a home recipe for their manufacture. It was quite simple, really, far simpler than getting a girl mouse and boy mouse together with a tiny bottle of wine: “If a soiled shirt is placed in the opening of a vessel containing grains of wheat,” he wrote, “the reaction of the leaven in the shirt with fumes from the wheat will, after approximately 21 days, transform the wheat into mice.”

This, of course, may be due to mice both enjoying wheat and being capable of climbing into jars. But Helmont had another recipe for scorpions. Just get yourself a brick, carve an indentation in it, and fill it with basil. Cover that brick with another, and place in the sun. In only a few days, “fumes from the basil, acting as a leavening agent, will have transformed the vegetable matter into veritable scorpions.” Such does basil in a brick oven rise like bread … with a stinger and claws.

Helmont’s recipes were the product of some 2,000 years of fallacious thinking known as spontaneous generation. Our forebears, you see, couldn’t for the life of them figure out how maggots could just up and appear in a corpse, or how oysters just seemed to materialize in the sea. They had to have been spontaneously generating, no sex required.

The East had its own similar theories, according to Andre Brack in his book The Molecular Origins of Life. The Babylonians thought worms spontaneously erupted from canal mud, and the ancient Chinese reckoned that aphids emerged from bamboo. For the Indians, flies came from dirt and sweat.

In the West, the theory goes back to Aristotle, who put forth the first thorough writings on spontaneous generation. Some critters are lucky enough to have sex, he argued (though not in those words—I’m editorializing here), but others emerge from “putrefying earth or vegetable matter, as is the case with a number of insects.”

No, oysters are not an aphrodisiac. And they certainly don't spontaneously generate from mud. I know that because I ate a good amount of mud as a kid, and oysters taste nothing like that. Image: Wikimedia

At work here, Aristotle says, is the “vital heat” present in air. Because this air is in water and water is in earth, therefore vital heat is in everything, “so that in a sense all things are full of soul.” So in the sea, oysters spontaneously generate from the lively mud, “the earthy matter hardening round them and solidifying in the same manner as bones and horns (for these cannot be melted by fire), and the matter (or body) which contains the life being included within it.”

Aristotle’s spontaneous generation was widely accepted in Europe and the Arab world for the next two millennia. In Antony and Cleopatra, for instance, the accomplished drunkard Lepidus notes that “your Serpent of Egypt, is bred now of your mud by the operation of your Sun: so is your Crocodile.” (Though as Frederick Turner writes in Shakespeare's Twenty-First Century Economics, such drunken ramblings may have been the great writer expressing sarcastic doubt toward spontaneous generation. Regardless, the theory was alive and well.) Later on, the greatest minds of the Renaissance and Enlightenment, including Isaac Newton and René Descartes, subscribed to the theory.

Then comes along the Italian physician and naturalist Francesco Redi, who had the sneaking suspicion that maggots come from flies instead of spontaneously generating. In a series of experiments in 1668, Redi left meat to rot in closed and open flasks, and then buried still more. Of course, maggots appeared in the open flasks, but not in the closed ones or on the buried meat. Not content to stop there, he added another flask of meat but covered this one in a fine Naples veil, which allowed air flow while still keeping flies out. Maggots did indeed appear—squirming along the veil, longing to reach the meat.

Hold Me Closer, Tiny Answer

Still, though, the theory of spontaneous generation would not die. And even as tiny worlds finally came into view in the 17th century with the introduction of the microscope, spontaneous generation simply adapted to the invention. In the mid-1700s, naturalist Georges-Louis Leclerc, Comte de Buffon (he seems like the type who would have gotten uppity if I didn’t use his full name, so there it is) put forth perhaps the most fanciful imagining of spontaneous generation yet.

A body, he said, is molecules organized like a mold. But after death these molecules are liberated from the body through putrefaction, then “captured by the power of some other mold.” The organic molecules are still full of life and are always active, and “rework the putrefied substance, appropriating coarser particles, reuniting them, and fashioning a multitude of small organized bodies.” Thus we get organisms like earthworms and mushrooms, he claimed.

I will posit that Louis Pasteur wore bow ties because, like me, he was inherently distrustful of regular ties, which are essentially potential nooses you wear out of the house each day, just begging to be slammed in a taxi door. Image: Wikimedia

Such did spontaneous generation evolve from oysters magically emerging from mud to focus on the tiny building blocks of living things. That is, until Louis Pasteur, that master of microbes, stepped in to put it down for good. Speaking at the Sorbonne Scientific Soirée of 1864 he went after proponents of spontaneous generation. Hard.

He was responding in particular to the experiments of naturalist Félix-Archimède Pouchet, director of the Rouen Museum of Natural History, who spurned germ theory—which was all the rage at the time—in favor of spontaneous generation. Pouchet had boiled water in a flask, killing off the microbes, and added hay he'd sterilized by heating to the point of carbonization, then immediately sealed the vessel to prevent contamination. Still, his water grew muck, ostensibly demonstrating “beyond the shadow of a doubt, the existence of microscopic creatures that entered the world without germs, and thus without parents resembling themselves,” in the sardonic words of Pasteur.

Pasteur argued that airborne microbes had fallen into Pouchet’s mixture in the time it took to seal the flask after boiling it. In his own experiment, Pasteur filled two long-necked flasks with meat broth. The first he brought to a boil as-is to kill off any existing microbes. Then he heated the neck of the second and bent it so that theoretically no airborne microbes could fall in, then brought that flask to a boil as well. As he predicted, the first exploded with growth after only a few days. The second remained “completely unaltered, not just for two days, or three, or four, or even a month, a year, three years, or four!”

Just because you couldn’t see life, it turns out, doesn’t mean that it isn’t there. Speaking to the soirée’s learned scientists, Pasteur triumphantly claimed that “the doctrine of spontaneous generation will never recover from the mortal blow inflicted by this experiment.”

Indeed it didn’t. And nor did Pouchet’s reputation, really (a Britannica entry that calls your ideas “mere curiosities” isn’t exactly what you’d call a glowing endorsement). The germ theory he so fervently attacked has helped science save the lives of countless people, thanks in no small part to his rival’s pasteurization techniques. Let’s appreciate Pouchet, though, for his biggest contribution to science: pissing off Pasteur. We all have our purpose, I suppose.

Reference:

Brack, A. (1998) The Molecular Origins of Life. Cambridge University Press