Microbes, most of them bacteria, have populated
this planet since long before animal life developed and they will outlive
us. Invisible to the naked eye, they are ubiquitous. They inhabit the soil,
air, rocks and water and are present within every form of life, from
seaweed and coral to dogs and humans. And, as Yong explains in his utterly
absorbing and hugely important book, we mess with them at our peril.
Every species has its own colony of microbes,
called a ‘microbiome’, and these microbes vary not only between species but
also between individuals and within different parts of each individual.
What is amazing is that while the number of human cells in the average
person is about 30 trillion, the number of microbial ones is higher – about
39 trillion. At best, Yong informs us, we are only 50 per cent human. Indeed,
some scientists even suggest we should think of each species and its microbes
as a single unit, dubbed a ‘holobiont’.
In each human there are microbes that live only
in the stomach, the mouth or the armpit and by and large they do so
peacefully. So ‘bad’ microbes are just microbes out of context. Microbes
that sit contentedly in the human gut (where there are more microbes than
there are stars in the galaxy) can become deadly if they find their way
into the bloodstream. These communities are constantly changing too. The
right hand shares just one sixth of its microbes with the left hand. And,
of course, we are surrounded by microbes. Every time we eat, we swallow a
million microbes in each gram of food; we are continually swapping microbes
with other humans, pets and the world at large.
It’s a fascinating topic and Yong, a young
British science journalist, is an extraordinarily adept guide. Writing with
lightness and panache, he has a knack of explaining complex science in
terms that are both easy to understand and totally enthralling. Yong is on
a mission. Leading us gently by the hand, he takes us into the world of
microbes – a bizarre, alien planet – in a bid to persuade us to love them
as much as he does. By the end, we do.
For most of human history we had no idea that
microbes existed. The first man to see these extraordinarily potent
creatures was a Dutch lens-maker called Antony van Leeuwenhoek in the
1670s. Using microscopes of his own design that could magnify up to 270
times, he examined a drop of water from a nearby lake and found it teeming
with tiny creatures he called ‘animalcules’. It wasn’t until nearly two
hundred years later that the research of French biologist Louis Pasteur
indicated that some microbes caused disease. It was Pasteur’s ‘germ theory’
that gave bacteria the poor image that endures today.
Yong’s book is in many ways a plea for microbial
tolerance, pointing out that while fewer than one hundred species of
bacteria bring disease, many thousands more play a vital role in
maintaining our health. The book also acknowledges that our attitude
towards bacteria is not a simple one. We tend to see the dangers posed by
bacteria, yet at the same time we are sold yoghurts and drinks that supposedly
nurture ‘friendly’ bacteria. In reality, says Yong, bacteria should not be
viewed as either friends or foes, villains or heroes. Instead we should
realise we have a symbiotic relationship, that can be mutually beneficial
or mutually destructive.
What then do these millions of organisms do? The
answer is pretty much everything. New research is now unravelling the ways
in which bacteria aid digestion, regulate our immune systems, eliminate
toxins, produce vitamins, affect our behaviour and even combat obesity.
‘They actually help us become who we are,’ says Yong. But we are facing a
growing problem. Our obsession with hygiene, our overuse of antibiotics and
our unhealthy, low-fibre diets are disrupting the bacterial balance and may
be responsible for soaring rates of allergies and immune problems, such as
inflammatory bowel disease (IBD).
The most recent research actually turns accepted
norms upside down. For example, there are studies indicating that the
excessive use of household detergents and antibacterial products actually
destroys the microbes that normally keep the more dangerous germs at bay.
Other studies show that keeping a dog as a pet gives children early
exposure to a diverse range of bacteria, which may help protect them against
allergies later.
The readers of Yong’s book must be prepared for
a decidedly unglamorous world. Among the less appealing case studies is one
about a fungus that is wiping out entire populations of frogs and that can be
halted by a rare microbial bacterium. Another is about squid that carry
luminescent bacteria that protect them against predators. However, if you
can overcome your distaste for some of the investigations, the reasons for
Yong’s enthusiasm become clear. The microbial world is a place of wonder.
Already, in an attempt to stop mosquitoes spreading dengue fever – a
disease that infects 400 million people a year – mosquitoes are being
loaded with a bacterium to block the disease. In the future, our ability to
manipulate microbes means we could construct buildings with useful microbes
built into their walls to fight off infections. Just imagine a neonatal
hospital ward coated in a specially mixed cocktail of microbes so that
babies get the best start in life.
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Hi, Could you send me with explanations, please?
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