I Contain Multitudes

Title: I Contain Multitudes – The Microbes within Us and a Grander View of Life

Author: Ed Yong

Publisher: The Bodley Head, 2016 (First)

ISBN: 9781847924186

Pages: 354

Individuality is a cherished trait of sagacious beings. Man is the only such animal which is conscious of its self. Man stands alone in his mental transactions with the outside world. This aloofness is way off the true state of things. Very small microbes and other inanimate objects thrive in our body and are present in very large numbers on all our body parts. The presence of microbes is thought to be a bad thing in routine awareness sermons, but this is not necessarily so. Microbes are beneficial or neutral to us on most of the occasions and provide immense service to us. They keep our guts healthy, calibrate our immune systems, make us less sensitive to allergens and can even exert influence on our brains. This horde of microbes in our body makes each individual human being a multitude which acts in tandem to work as a symbiotic whole. Ed Yong is an award-winning science writer who regularly contributes to leading journals and scientific publications.

The author makes a brilliant comparison scheme to present the contrast between life forms almost perennially lived on earth against others who are relatively latecomers to the party of life. He equates our planet’s entire life to a human year in which the present is just before midnight on December 31. On such a scale, the entry of humans was just half an hour ago, at 11.30 pm, while microbes ruled the globe between the months of March to October, that is, between their entry and the advent of higher organisms. This ingenuous example clarifies all doubts on the antiquity of microbes as compared to mammals or other higher forms of life.

Microbes are everywhere, but due to the very small size of them, they remained invisible to mankind till the seventeenth century. It was then Antony van Leeuwenhoek, a pioneering lens-maker in Holland, witnessed these organisms everywhere – in water, in hand tools, in his body, home and everywhere! For a time, others couldn’t make lenses with the resolving power as Leeuwenhoek’s, but when at last they did, the scholars were shocked to find themselves colonized by these microbes. It took nearly another century to distinguish the good from the bad. Many microbes live in symbiosis with their hosts. It can also be said that microbes help us become what we are by modifying the genes of parent organisms in subtle ways. Biologists have experimentally demonstrated that organisms that live in sterile Lab-like environments where the microbes are strictly controlled suffer growth problems in the absence of friendly bacteria. Yong includes examples where the microbes affect the growth of brain. Specific strains of bacteria can be encouraged with the help of probiotics (the reverse process as antibiotics). Lack of exposure to symbiotic microbes had resulted in depression and anxiety in the hosts.

The book argues that the sharp distinction between good and bad microbes is an oversimplification. Even the good ones create life-threatening situations when their position is changed, say from the gut to the blood stream. Mitochondria are present in every mammal cell, which generates the energy the cell so dearly needs. Scientists presume that mitochondria were independent microbes in the beginning of life and later settled inside the animal cell in a case of mutually beneficial symbiosis. Even with a history of living together for billions of years, if the mitochondrion is to enter the blood stream somehow, the immune system of the host attacks it with vigour as if it was a foreign particle and not a part of its own body. Yong presents the case of Helicobacter pylori, the bacterium in our gut that causes ulcer and stomach cancer. A very bad guy, obviously. But what will happen if we kill all of them in our guts? Scientists warn that we are in for more trouble, as these bacteria also protects against oesophageal cancer! As in life, it is a fine line that separates the good from the ugly in the case of microbes as well.

The clever ways in which mothers help their babies grow microbes in their guts is interesting to read. The author has used many scientific terms to describe the process, but one such case is very noteworthy. Human breast milk contains a family of chemicals called Human Milk Oligosaccharides (HMO) which can’t be digested by the infant! Why on earth are such chemicals present in mother’s milk? The shocking answer is that these are good for a specific species of bacteria in the child’s long intestine. HMO nourishes these microbes, which in turn produces short-chain fatty acids. These feed the infant’s gut cells by making adhesive proteins that seal the gap between gut cells and anti-inflammatory molecules that calibrate the immune system. Needless to say, babies nurtured with bottled milk don’t develop this familiarity of the immune system to microbes. This results in inflammations where the immune system overreacts even to benign external particles. The book also speculates that microbes control obesity. Obese people have more Firmicutes and fewer Bacteroidetes than their leaner counterparts in their stomach. Transferring these microbes among lab mice showed that those mice which received microbes that characterized obesity put in more weight and vice versa. There is, however, no assurance that this result can be repeated in humans.

Do you remember the scary day when New Scientist magazine trumpeted on its cover that Darwin was wrong? It talked about a system of gene transfer which is horizontal, that is, from one individual to another without any reproductive act called Horizontal Gene Transfer (HGT). This differed with the vertical scheme Darwin had in mind, that is, from parent to offspring. The devil was in the details, and if you had read the whole article, it emphasized Darwin’s theorem rather than upsetting it. But for those who judge a book by its cover, it presented an avoidable opportunity to score on the supposed ‘error’ in Darwinism. HGT is widely seen in the world of microbes. Yong presents the curious case of the ‘nori’ seaweed that is a delicacy in Japan. Humans normally can’t digest the seaweed as the gut bacteria are unable to process them. But those who ate them first ingested marine bacteria skilled in the job. It exchanged genes with normal gut bacteria and entered its genome. Then it proceeded to colonize people via the normal biome transfer between parent and child.

In the latter chapters of the book, the author describes about several revolutionary techniques of healing with bacteria, which are generally interesting but revolting at times. The faecal microbiota transplant (FMT) techniques may provide a fast cure for stomach-related issues, but it shows that a microbiologist’s career is not always glamorous! Manipulating the microbiome of an entire region or a person is discussed at length, but Yong tactfully stops short of anticipating repercussions that may arise when one plays with an entire biome. If the author is to be believed – and there are many solid reasons to do so – microbes are definitely going to play a significant part in formulating the therapies of the future. The book is neatly written and displays the confidence of the author in the beneficence of what he describes to mankind. A number of colour plates add to the visual appeal. A good number of Notes and a comprehensive index enhance the utility of the book.

The book is highly recommended.

Rating: 3 Star