Even when compared to their microscopic kin, yeasts appear feeble species.

They aren’t particularly good at moving from place to place.

They don’t notoriously cause disease, and, unlike other fungi, they can’t even produce colorful mushrooms.
Yet yeasts have one remarkable trait that separates them from other life forms. They embody an alchemist’s secret, which makes them one of the most useful creatures to humans.

They can make alcohol.

In the process of fermentation, while feeding on sugar and transforming it into alcohol, yeasts simultaneously produce a bouquet of chemicals interpreted as flavors and aromas which humans have been enjoying for millennia. Each beer you’ve ever drunk has been the life work of many millions and millions of yeast cells.
For organisms that can’t run or fly away, yeasts are remarkably elusive in nature. There are no footprints to follow, calls to hear, or traps to set.

There are two things we do know: yeasts like sugar, and sugar is rare in nature. Some yeast wranglers hike through Patagonian forests, finding wild yeasts clinging to sweet tree sap.

Some wranglers tread through lush orchards, finding yeasts nestled near the stems of rotting fruit. Still others find yeasts swimming in the pools of nectar in flowers, or in the dregs of wine in oak barrels.
I am of a tribe of wranglers that is, like the yeasts themselves, opportunistic. I let sugar-seeking insects do the collecting of yeasts for me.
As a wasp travels from rotten fruit to tree sap to nectar, gulping down sugars, it is also gathering yeasts.
When I return from the field with bags of angry insects, the real work begins. I extract and grow the yeasts, then test and identify them. In doing so I find out which yeasts might be able to make beer, and which ones could be dangerous.
Along with other scientists and brewers, I am now hunting for what conditions are best for wild yeasts, hoping that just one of them will stick around long enough to see the inside of a brewery.

Most cannot.
Many yeasts recoil from the domestic life and are unable to flourish in the boiled grains of beer. Still others wreak chemical havoc in beers, adding flavors like wet dog, horse sweat, and vinegar.