The Upside Down: Why We Underestimate Fungi at Our Peril

Perhaps it is the atavistic fear of something growing inside us and consuming us from within that makes us feel so ambivalent towards fungi, writes John Mitchinson

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The success of the HBO series The Last of Us, based on an equally successful video game, is in no small part due to its clever re-working of the zombie theme.  

Human life on the planet is decimated by a pandemic in which a deadly fungus enters our bodies through broken skin and turns us into jerking puppets, intent on eating flesh in order to spread our spores. There is no cure. Billions of humans don’t just die but become absorbed into a vast fungal network.

This may sound like the stuff of nightmares, but it is based on a very real fungus –  Ophiocordyceps unilateralis – which has evolved a deadly relationship with a species of carpenter ant. 

The infected ant finds itself unable to control its own body. It is propelled to climb – a condition called ‘summit madness’. Once it reaches a particular height (25 centimetres above the ground), the ant’s jaws lock onto a vein on the underside of a leaf. There it remains, unable to move, as fungal fibres – hyphae – dissolve and consume its internal organs until eventually a mushroom stalk erupts from its head and showers spores on its relatives toiling below.

As Merlin Sheldrake describes it in Entangled Life, “in physiological, behavioural and evolutionary terms, the ant becomes fungus”.

Luckily for us, Ophiocordyceps is very fussy about where it lives. Our body temperatures are too high for it to survive inside us, so The Last of Us relies on this bit of manipulation and the fact that the violent consumption of human flesh becomes the vector for spores, rather than inhalation, to give the drama its bite. 

But the idea that fungi are simply passive benign fellow travellers is also wide of the mark.

In 2022, the World Health Organisation published its first action plan for invasive fungal diseases, which already account for 1.7 million deaths a year (three times more than malaria). “Despite the growing concern,” the report warns, “fungal infections receive very little attention and resources.” It goes on to list 19 fungal pathogens and ranks them in order of threat. Of these, four were designated as ‘critical’.

One of the critical four, Candida auris has an origin story straight out of TV drama. It was discovered in 2009 in the ear canal of a 70-year-old Japanese woman at the Tokyo Metropolitan Geriatric Hospital in Japan (auris means ‘ear’). Since then, it has spread rapidly throughout the world, causing severe blood and ear infections and killing one in three people it infects. It thrives in hospitals, lurking in breathing and feeding tubes, intravenous drips and blood pressure cuffs. What makes it dangerous is that it is resistant to pretty much all anti-fungal medication: a suspected outbreak can quickly close a whole hospital wing. 

Another deeply unpleasant fungal infection on the rise is mucormycosis, or black fungus, caused by a widely distributed family of pin moulds called Mucorales (when a piece of fruit collapses into a black fungal mess, that would be a mucor-fungus). Usually entering through the sinuses, it multiplies rapidly and can cause tissue death leading to severe disfigurement and/or death in half the cases it infects. A recent outbreak in India led to more than 4,000 deaths.

One thing that marks out fungal diseases is that they are opportunistic: they tend to flourish where the immune system is compromised, affecting people recovering from surgery, undergoing chemotherapy, suffering from diabetes or HIV, or dealing with the still imperfectly understood effects of the Coronavirus. If they spot a chance to thrive, they take it, sometimes with a speed that seems unnatural. 

Perhaps it is that atavistic fear of something growing inside us and consuming us from within that makes us feel so ambivalent towards fungi. They, literally, thrive on death and decay. As Merlin Sheldrake puts it, “fungi are veteran survivors of ecological disruption. Their ability to cling on – and often flourish – through periods of catastrophic change is one of their defining characteristics”.

This perspective shift might be the most important lesson fungi can teach us, here on our ailing overheated planet. 

In 2016, studies at New York and Johns Hopkins Universities gave patients suffering from severe anxiety and depression a single dose of psilocybin (better known as ‘magic mushrooms’) alongside their regular course of psychotherapy. The results were astonishing. In 80% of cases, patients reported significant reduction in their symptoms and this lasted for at least six months afterwards. In particular they described “a movement from feelings of separateness to interconnectedness”. 

Through subtle chemical intervention, were they offering a tantalising glimpse of life as a fungus? Not consuming us like zombie ants to shake down spores but transforming our minds, freeing us from ego anxiety, allowing us to feel the mycelial-like connectedness of all things – and our true place in the natural world.

John Mitchinson is a writer and publisher and co-founder of Unbound, the world’s leading crowdfunding platform for books. He was one of the founders of BBC’s ‘QI’

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