I Contain Multitudes: The Microbes Within Us and a Grander View of Life

by Ed Yong

pangolin comes from the Malay word pengguling, meaning ‘something that rolls up’.

abundant microscopic menagerie, collectively known as the microbiota or microbiome.

When Neil Armstrong and Buzz Aldrin set foot on the Moon, they were also taking giant steps for microbe-kind.

‘We’re born alone, we live alone, we die alone’, he was mistaken. Even when we are alone, we are never alone. We exist in symbiosis –

Every one of us is a zoo in our own right – a colony enclosed within a single body. A multi-species collective. An entire world.

We can talk about the diversity of microbial species.

We can treat disease-causing microbes – pathogens – as invasive creatures, like cane toads or fire ants.

We can compare the gut of a person with inflammatory bowel disease to a dying coral reef or a fallow field: a battered ecosystem where the balance of organisms has gone awry.

Through microbes, we find unity with our fellow creatures, despite our incredibly different lives.

All zoology is really ecology. We cannot fully understand the lives of animals without understanding our microbes and our symbioses with them.

In fact, we are legion, each and every one of us. Always a ‘we’ and never a ‘me’.

Forget Orson Welles, and heed Walt Whitman: ‘I am large, I contain multitudes.’

Before October, almost every living thing on the planet consisted of single cells. They would have been invisible to the naked eye, had eyes existed.

we are now in the Anthropocene: a new geological period characterised by the enormous impact that humans have had on the planet.

there are more bacteria in your gut than there are stars in our galaxy.

‘Animals might be evolution’s icing, but bacteria are really the cake.’4 They have always been part of our ecology. We evolved among them. Also, we evolved from them.

They pack almost all their DNA into a central nucleus, a structure that gives the group its name – ‘eukaryote’ comes from the Greek for ‘true nut’.

mitochondria – bean-shaped power stations that supply cells with energy.

Before that point, life on Earth could be divided into two camps or domains: the bacteria, which we already know about, and the archaea, which are less familiar and have a fondness for colonising inhospitable and extreme environments.

a bacterium somehow merged with an archaeon, losing its free-living existence and becoming entrapped forever within its new host.

It’s our creation story: two great domains of life merging to create a third, in the greatest symbiosis of all time. The archaeon provided the chassis of the eukaryotic cell while the bacterium eventually transformed into the mitochondria.5

‘black hole at the heart of biology’.

By forging a union, those two microbes defied the odds and enabled the existence of all plants, animals, and anything visible to the naked eye – or anything with eyes, for that matter.

These disease-causing microbes – pathogens – have traumatised humans throughout history, and have left a lingering cultural scar.

Microbes matter. We have ignored them. We have feared and hated them. Now, it is time to appreciate them, for our grasp of our own biology is greatly impoverished if we don’t.

In March 1854, a 31-year-old British man named Alfred Russel Wallace began an epic eight-year trek through the islands of Malaysia and Indonesia.

Wallace is today heralded as the father of biogeography – the science of where species are, and where they are not.

‘Every species has come into existence coincident both in space and time with a pre-existing closely allied species,’

fittest individuals survive and reproduce, passing their advantageous traits to their offspring. That is, they evolve, by means of natural selection.