I contain multitudes
Wendy Moore reviews
Ed Yong’s book about microbes
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.
Questions 14-16
Choose the correct letter,
A, B, C or D.
Write the correct letter
in boxes 14-16 on your
answer sheet.
14
What point does the writer
make about microbes
in the first paragraph?
A They adapt quickly to their environment. B The risk they pose has been exaggerated.
C
They are more plentiful in animal life than plant life.
D
They will continue
to exist for longer
than the human
race.
15
In the second
paragraph, the writer
is impressed by the fact that A each species
tends to have vastly different microbes.
B
some parts of the body contain
relatively few microbes.
C
the average individual has more microbial cells
than human ones.
D
scientists have limited
understanding of how microbial cells behave.
16 What is the
writer doing in the fifth paragraph?
A explaining how a discovery was made
B comparing scientists’ theories about
microbes C describing confusion
among scientists
D giving details of how microbes cause
disease Questions 17-20
Complete the summary using the list of words, A-H, below.
Write the correct
letter, A-H, in boxes 17-20 on your answer sheet. We should be more
tolerant of microbes
Yong’s
book argues that we should be more tolerant of microbes. Many have a beneficial
effect, and only a relatively small number lead to 17............................................. And
although it is misleading to think of
microbes as ‘friendly’, we should also stop thinking
of them as the enemy. In fact, we should accept that our relationship
with microbes is one based on
18 ………………… .
New research
shows that microbes
have numerous benefits
for humans. Amongst
other things, they aid digestion, remove poisons, produce
vitamins and may even help reduce obesity. However, there is a growing
problem. Our poor 19........................................................... , our overuse of antibiotics, and our excessive focus
on 20.......................... are upsetting the bacterial balance and may be contributing to the huge increase
in allergies and immune system problems.
A |
solution |
B |
partnership |
C |
destruction |
D |
exaggeration |
E |
cleanliness |
F |
regulations |
G |
illness |
H |
nutrition |
|
|
Questions 21-26
Do the following statements agree with the claims of the writer
in Reading Passage
2? In boxes 21-26 on your answer sheet,
write
YES if the statement agrees with the claims
of the writer NO if the statement contradicts the claims
of the writer
NOT GIVEN if it is impossible to say what the
writer thinks about this
21
It is possible
that using antibacterial products in the home fails to have the desired effect.
22
It is a good idea to ensure that children come into contact with as few bacteria as possible.
23 Yong’s book contains more cause studies
than are necessary.
24
The case study about bacteria that prevent
squid from being attacked may have limited appeal.
25
Efforts to control
dengue fever have been surprisingly successful
26 Microbes that reduce the risk of infection have already been put inside the walls of some hospital wards.
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