Ten million years ago, our hominid ancestors acquired a mutated gene that enabled them to digest ethanol. Foraging the landscape, they found sustenance — and, presumably, gratification — in fermented fruits that had fallen to the ground, providing an evolutionary survival advantage for our future bipedal species. Half a billion years earlier, another mutation led to the budding yeast species Saccharomyces cerevisiae, commonly known as brewer’s or baker’s yeast. This single-celled yeast metabolises sugar to create ethanol, an alcohol safe for human consumption. Saccharomyces cerevisiae means sugar fungus for beer, and it was an ancient mutation from fission yeast, Schizosaccharomyces pombe — pombe is Swahili for beer, still cultured today to ferment African beer and Jamaican rum.
Since the emergence of Homo sapiens, humans have harnessed yeast to prepare fermented beverages for medicinal purposes and consumption, a custom found across all cultures and geographies. Nature’s abundant sugars in honey, fruit, nectar, and sap attract this nomadic yeast to feed on these sugars and initiate fermentation to produce alcohol. More than 10,000 years ago, the Neolithic Revolution introduced domesticated agriculture, delivering an efficacious milestone to alcohol manufacture. In West Asia, selective breeding of rye, wheat, barley, and millet transformed cereals into beer and bread, while the discovery of malting encouraged the conversion of starches into sugars for yeast to thrive in fermentation.
As cereal cultivation spread across the Western Hemisphere, Saccharomyces travelled with it, cojoining its diaspora of wild strains that had long inhabited the planet’s flora and soil. Domesticating new strains for brewing enabled Northern Europe’s agrarian societies to develop thriving beer cultures. Before it was known as yeast in medieval times, it was described as ‘godisgoode’, revered for its miraculous properties. To maintain healthy yeast strains, households employed methods such as sourdough kneading, wild harvesting, and incubating yeast cultures. As more distilleries scaled up into an industry, vast quantities of yeast were needed to sustain production at volume.
Scotland’s new capital distilleries were mainly established in rural areas during the late 18th century, where they lacked local breweries to meet their high yeast demands. In 1756, Scotland had fewer than fifty public breweries producing 10.7 million gallons of beer. In contrast, England reported thousands of breweries producing 215 million gallons, supplying yeast to many of England’s large malt distilleries. By 1781, London’s massive porter breweries brewed 48 million gallons of strong beer and shipped 100,000 gallons of yeast to Scotland, a figure that quadrupled by 1784.
The invention of dried yeast by Matthew Felton of London in 1796 ensured that healthier shipments of live yeast from London were dispatched to Scotland’s distilleries for another half-century. In America, distilling was also an agricultural by-product that developed into a cottage industry, commonly supplying raw spirits to large East Coast rectifiers for reprocessing into marketable whisky. By 1850, only 431 breweries operated in the US. They selected strains with good alcohol yields and desirable flavours, pitching yeasts into donor (mother) jugs and storing yeast cultures in cold wells, ponds, or subterranean boltholes during summer to re-incubate for distilling season.
By the late 19th century, advancements in bioscience transformed yeast selection and propagation, leading to a sixfold increase in alcohol yield. This culminated in DCL’s distiller’s yeast M1 strain in the early 1950s, a new hybrid intraspecies that improved yeast tolerances, particularly high ethanol production. Today, while thousands of cultured yeast strains are available from laboratories, each distillery also hosts its resident microflora and wild yeasts, contributing their microbial terroir, which can add sensory nuances and subtly influence the spirit’s geographic production.
