There are roughly 100 trillion cells in your body, but only about 10 trillion of them are human. The rest are microorganisms such as bacteria and parasites.
Which begs some fundamental questions: Who are we, really? We think of ourselves as individual humans, but from the bacteria’s point of view, we’re more like giant hotels, engineered to carry them around the planet’s surface and meet their biological needs. In fact, it’s not incorrect to think of our bodies as colonies or super-organisms, alive thanks only to the intricate genetic and biochemical dance that’s evolved over hundreds of millions of years. (It now seems that as much as 8 percent of the human genome is composed of DNA from retroviruses.)
These are themes that have long interested two Knight Science Journalism alumni from Germany, Hanno Charisius (2010-11) and Richard Friebe (2006-07). They recently joined forces to write a book about the bacteria all humans live with—in their guts, on their skins, in their eyes, and elsewhere. It’s called Bund fürs Leben – Warum Bakterien unsere Freunde sind. According to Friebe, that translates into something like “Together for Life—Why Bacteria Are Our Friends.”
Friebe and Charisius write about the signifance of the human-bacteria symbiosis for health and disease; the implications reach far beyond the gut (home to the majority of our bacterial passengers) to topics like cancer, heart disease and mental illness. The book also questions the claims of companies selling all kinds of services related to the human microbiome, from so called “effective microorganisms” via probiotics to fecal transplants, and assesses the near-term potential of microbiome research.
Bund fürs Leben was short-listed for “science book of the year” by the Austrian government in the medicine and biology category. (Voting is underway until Monday, January 12!) In a previous collaboration, also for the German publisher Hanser, Charisius and Friebe published Biohacking together with another Knight alum, Sascha Karberg (2008-09). I interviewed Charisius and Friebe about their latest book via e-mail.
Wade Roush: Why should lay people care about the microbiome?
Hanno Charisius: Everybody should care about their microbiome. It is part of what and who we are. The microbial communities in our guts not only help feed us by breaking down nutrients, which is important enough. They also play powerful roles in all kinds of unexpected aspects of health and disease, from cancers to heart conditions and even mental illness. If we learn how to maintain a balanced relationship with them—or in case of disruption how to reestablish one—it will help us live healthier, probably even happier, lives.
Richard Friebe: Microbes are indeed part of ourselves. Of our “selfs”! If we care about our own organs, our cells, our genes, because we see them as key to our well-being, we also should care for all those microbes associated with us, and about what functions their genes—which are many, many more then our own—provide.
WR: In many ways, our scientific understanding and popular awareness of the importance of the human microbiome is still at a very early stage. Yet there is already the potential for a lot of hype or misinformation around this subject. How well informed is the average news consumer about the role of bacteria in our lives?
HC: It is still rather common to react with disgust and probably fear when the topic of bacteria in our immediate living environments comes up. The hygiene industry has done a thorough job in teaching us to fight bacteria where we can, because they can make us sick. But really only a few bugs put us in danger. And more importantly, trying to kill bacteria may put us even more in harm’s way, be it by actually providing niches for the bad microbes by killing a lot of good ones, or by facilitating the emergence of more and more antibiotic-resistant pathogenic strains.
RF: But your question seems to also allude to the exact opposite: a possible hype in terms of microbes being seen as a new panacea. And it is true, there now is already an industry that prospers on exactly that proposition, with sometimes outrageous claims, completely unfounded by science as yet. And this may actually put users in real danger. If, for example—and sorry for the bluntness—you buy someone’s poop on the internet today in the hope of curing your stomach-ache or of getting slim by putting it into your own gut, you’re taking a real risk. And of course such approaches can also put earnest research in this area into undeserved disrepute.
WR: Are some people using probiotics without understanding the real science or hazards behind them?
RF: Probably, because not even probiotics, which are the poster child of “good bacteria,” are well enough investigated as yet as to be able to give much universal or specific advice on their use.
HC: Many people use probiotics without knowing what the bugs they are swallowing might or might not do. There is not a whole lot of evidence for probiotics so far. Only a few have shown significant benefit in clinical studies, and there have been few but serious side effects, too. It’s complex. What probiotics do depends on many factors and interactions, many of them probably still unknown. Whoever claims to know what is going on here is either far ahead of all those respectable scientist working in the area—or a liar.
WR: The more we learn about the symbiotic relationships that keep us alive, the more it seems that we might have to abandon our self-image as unitary organisms. It seems like we’re closer to being colonies, and this understanding should inform biomedical practices and perhaps even our philosophy about what it means to be human. Do you agree or disagree?
HC: It might be a bit of a narcissistic offense for some people to learn that we are human-microbial communities. But it is true. Each of us is a super-organism. But, if that helps: Each such super-organism is very unique indeed.
RF: Related to your proposition, let me also put one forward: Humans are currently experiencing a major transition in terms of how and where they see themselves in this world. It is not the first time that this has happened. Copernicus removed us from the center of the universe, Darwin removed us from the sunny spot of creation, Freud and now modern neuroscience too have told us that our conscious mind is much less powerful than we had thought.
And now? Now we have to accept that a fair bit of us is microbes with no brain, not even a nucleus, and that they pull quite a number of strings. I would call that the fourth “Blessure narcissique” that humankind now has to endure. But of course at least Hanno and I are not too depressed about that. We find it fascinating and actually empowering. We humans have an interesting place in the web of life, which we now become aware of. And that’s pretty cool.
WR: Is your book especially directed at a German readership?
RF: Not really. We feature the research and the stories and the people whom we consider most relevant.
Hanno: Some of those protagonists are Germans, but most of them actually, and not surprisingly, work in the US and Canada.
WR: How did this collaboration come about? And how has the Knight Fellowship experience affected your work on the project?
HC: I actually took a class with Harvard’s Roberto Kolter during my fellowship. There I first learned about the fascinating ecosystem within ourselves, and how we are damaging it with antibiotics and food that is not microbe friendly anymore. From there I cultivated the idea of writing a book. The first working title was “Guts”, which [former KSJ director] Phil Hilts came up with when I told him about my idea of writing a book about poop.
RF: I had already been writing articles about microbes in the gut for years when in 2011 I came across research suggesting that intestinal bacteria play a significant role even in how we feel and think and function mentally. There was clearly more to our microbes then helping us digest bananas or creating certain odors. And that whole story had never been told in a poopular—I mean, popular—book. So Hanno and I, after collaborating on our previous book Biohacking* (2013, written together with another friend and former Knight Fellow, Sascha Karberg), decided to tell this story together. And in it we go beyond the gut bacteria, too. After all, there’s lots of them on our skin as well, in our mouths, in our eyes, on our reproductive organs, etc.. And I think we also made it as entertaining as possible, although we tried to avoid falling into the trap of pulling all the obvious jokes related to the subject-matter.
HC: Unfortunately, there is not an all too interesting answer as to why two former Knight Fellows got together to write a book. It’s simply because we had for years been not only respectful colleagues but close friends.
RF: Surprisingly, even after doing this book, which really meant working our guts out, we still are…
Update, February 11, 2015: Friebe got in touch this week to let us know that Bund fürs Leben will be translated into Mandarin and published by Business Weekly Publications (Cite) in Taipei.