If you had to choose the organism that has most impacted the course of human history — more than any crop, any domestic animal, any pathogen — the most honest candidate would be a fungus. Or more accurately: several fungi, each in its time, each irreversibly changing what was possible for human civilization.
Chapter 1: Yeast and the origin of civilization (10,000 BCE)
There is a fascinating academic debate about whether humans invented agriculture to grow grain for making bread or for making beer. Archaeological evidence from Göbekli Tepe in Turkey (12,000 years old) and Raqefet Cave in Israel (13,000 years old) suggests that grain fermentation — i.e., beer — may have preceded bread.
The agent of that fermentation is Saccharomyces cerevisiae — brewer's yeast — a microscopic single-celled fungus that has been co-evolving with humans longer than we have been sedentary. Yeast converts sugars into alcohol and CO₂. For Neolithic humans, beer was:
- Safer than water — alcohol eliminates pathogens that killed in early settlements
- Calorically dense — a source of nutrition in times of scarcity
- Socially cohesive — archaeological evidence shows that beer was produced and consumed in ritual and community contexts
For centuries, brewers did not know they were working with living organisms. They passed the same unwashed wooden vessel from batch to batch — transmitting the yeast without understanding why it worked. It was an empirical technology perfected over generations, based on observation and tradition, centuries before the concept of microorganisms existed.
Chapter 2: Louis Pasteur and the germ revolution (1857)
In 1857, the French chemist Louis Pasteur received a peculiar assignment: the Lille brewing industry asked him to investigate why some batches of beer inexplicably spoiled. What Pasteur found changed the history of science.
By studying fermentation under a microscope, Pasteur demonstrated that it was produced by living microorganisms — yeasts — not by purely chemical processes as the dominant theory believed. It was the first step towards the Germ Theory of disease — the idea that infectious diseases are caused by specific microorganisms, not by “miasmas” or corrupted airs.
From that discovery, made by studying beer, came pasteurization, antibiotics, modern vaccines, and practically all contemporary microbiology and infectious medicine. All because a Lille brewer had a quality problem with his product.
Chapter 3: Alexander Fleming and the most important accident in history (1928)
On September 28, 1928, Alexander Fleming returned to his lab at St. Mary's Hospital in London after a vacation. He found that one of his Petri dishes with a Staphylococcus aureus culture had been contaminated by a fungus — probably spores that entered through the window from the building below, where a colleague was cultivating fungi of the genus Penicillium.
Around the contaminating fungus, the bacteria had died. Instead of throwing away the “ruined” plate, Fleming carefully examined it and wrote in his notebook: “This may be important.”
The compound that the fungus produced to defend itself against bacteria — which Fleming called penicillin — turned out to be the most important antibiotic in human history. Since its massive clinical introduction in World War II (1943-1945), penicillin and its derivatives have:
- Saved over 200 million lives directly
- Made modern surgery possible (without antibiotics, postoperative infections were the main cause of surgical mortality)
- Transformed deadly diseases (pneumonia, meningitis, syphilis) into treatable conditions
- Inaugurated the age of antibiotics — which, although today facing the crisis of bacterial resistance, remains one of the greatest achievements of medicine
Fleming shared the Nobel Prize in Medicine in 1945 with Howard Florey and Ernst Boris Chain, who developed the process for mass production of penicillin. In his acceptance speech, Fleming warned: “There is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.” This was 1945. What he described is exactly the antibiotic resistance crisis we face today.
Chapter 4: Cyclosporine and organ transplants (1969)
In 1969, Jean-François Borel — a researcher at the pharmaceutical company Sandoz — analyzed soil samples collected by his colleagues on scientific trips. A sample from the Norwegian plateaus contained a new fungus: Tolypocladium inflatum. The compound it produced — cyclosporine — had an unusual property: it selectively suppressed the activity of T lymphocytes without killing other immune system cells.
That selectivity changed everything. Before cyclosporine, organ transplants had one-year survival rates of less than 50% — the body rejected the foreign organ. With cyclosporine, the rate exceeded 80%. The first heart transplant with cyclosporine was in 1983. Today:
- More than 170,000 solid organ transplants are performed worldwide annually
- Cyclosporine or its derivatives are standard in practically all of them
- All those lives — all of them — depend on a compound from a Norwegian soil fungus
Chapter 5: Statins and cholesterol (1970s)
In 1973, Japanese biochemist Akira Endo isolated a compound from the fungus Penicillium citrinum, which he called mevastatin — the first inhibitor of HMG-CoA reductase, the key enzyme in cholesterol synthesis. It was the first statin.
Fungus-derived statins and their synthetic versions are today the most prescribed drugs in the world: more than 200 million people take them daily to reduce cardiovascular risk. The statin pharmaceutical industry moves more than $14 billion annually.
The paradox of the modern fungus
There is something deeply ironic about Western civilization's relationship with fungi: in many Anglo-Saxon cultures, wild mushrooms generate distrust and aversion — the “mycophobia” that Wasson described. And yet, practically every hospital bed in the Western world depends on fungal compounds: antibiotics save surgery, statins protect the heart, cyclosporine makes transplants possible, insulin produced by yeasts treats diabetes.
Modern civilization does not fear fungi. It depends on them — it just doesn't know it.
→ The Fungi kingdom in depth
→ FungiFacts #1 — 15 facts that will change your perspective
→ The active biocompounds of our fungi
References: Pasteur L. (1857). Mémoire sur la fermentation lactique. Comptes rendus. Fleming A. (1929). On the antibacterial action of cultures of a Penicillium. British Journal of Experimental Pathology. Borel J.F. et al. (1976). Biological effects of cyclosporin A. Agents and Actions. PMID 8969