The Spontaneous Generation Cookbook

How to make mice from scratch

(serves 2—if desperate)

 Ingredients:

• 1 soiled shirt
• 1 sheaf of wheat

Method:

1. Lay shirt on wheat.
2. Leave in sun for 21 days (avoid pungent aroma).
3. The shirt’s sweat will produce mice.

How to create a scorpion

(serves 2 brave souls)

Ingredients:

• 2 bricks
• 1 basil leaf

Method

1. Place basil between two bricks.
2. Leave in sun for three days.
3. Avoid getting stung by scorpions when you return.

These recipes are paraphrased from 17th-century Dutch chemist Jan Baptist van Helmont. Luckily, he is remembered for discovering gases such as carbon dioxide, not for conjuring mice and scorpions.

But these recipes weren’t just fun magic tricks. They were legitimate experiments testing the long-supported theory of spontaneous generation. From Ancient Egypt to Aristotle to Shakespeare, people believed for millennia that simple organisms arose spontaneously from non-living matter. Whether it was maggots formed from rotting flesh or frogs made from the mud of the Nile, this was apparently a sensible explanation for where babies came from. Who needs parents when you can build yourself out of underwear, sweat and mud?

You might laugh at these “scientists” for not noticing tadpoles chilling in the river or flies laying eggs in the dead. But how would you have unravelled these mysteries with no microscope, no tracking devices, no cameras? Even today, some creatures’ origins remain elusive. We have no good answer to the “eel question”: we’ve never seen eels mate and have no idea how baby eels are born. The matter even led biologist Max Schultze to lament, on his deathbed, that “all important questions have now been settled . . . except the eel question”.

Reproduction has always inspired bizarre theories. Aristotle believed sperm contained miniature, preformed humans. He thought the tiny people expanded in the womb, like those dinosaur egg toys that hatch in water. But without a microscope and knowledge of genetics, can you blame him for not predicting the entire field of developmental biology?

It took centuries of experimentation to discredit spontaneous generation. Microbiologist Louis Pasteur’s experiments in the 1860s were the final nail in the maggot-filled coffin. I like imagining that old-school scientists tinkered in their basements for sheer joy, but Pasteur was on a (very practical) mission: saving French industry from the spoilage of wine, beer and milk.

The experiments he performed were damning evidence that life only comes from other life. They also led to pasteurisation—heating something to kill pathogens—which enables us to consume milk and other foods safely.

Even though proponents of spontaneous generation were wrong, they contributed immensely to the search for the source of life. They built the foundations that enabled scientists like Pasteur to save countless lives through germ theory. So, next time you drink a glass of milk (or beer or even nuts if dairy isn’t your thing), serve it with a side of appreciation for the scientists that got it wrong.