March 19, 2013 | 6
Every day it seems like some new discovery is revealed ab0ut the microbial life on our bodies, in our bodies and around our homes. The tendency in writing about such studies is to make sweeping conclusions about what is and is not and, of course, how we should live and what we should do. But the truth is that these new studies are part of a big lunge science is making into a great darkness. The lights we are shining are revealing treasures and discoveries, but no one has a lens big enough to see the whole picture, not yet anyway. The temptation is to stand at the site of each new discovery and try to make the prediction about what is next. I’m going to do something else here. I’m going to try to predict not the next discovery but instead the next ten years. You can check back in ten years to tell me whether I was full of it. I probably am, but what fun is a blog if you can’t speculate a bit. For what it is worth, these wild ideas come largely from extrapolating what we know about ecology of non-human species in general and applying it to humans and the microbes around us. In other words, if humans obey the ecological regularities the last fifty years of ecology have revealed then it will be discovered that…
Image 1. Nostradamus as painted by his son Cesar (who, it is rumored, Nostradamus predicted would be a girl)
1-Many diseases result from having a low diversity of good bacteria on your skin, in your nose or in your gut. The benefits of having a high diversity of good bacteria are multiple. They protect you by interacting with your immune system, but also by actively doing battle with newly arrived species.
2-Antibiotic wipes, soaps, toothpastes, underpants and other antimicrobial compounds, particularly those with Triclosan, make you more likely to get sick rather than to get healthy. In a decade, people will begin to question how we possibly considered using them.
3-The benefit of hand washing (which is not yet understood) is due to the ability of washing with soap and water to differentially kill the pathogens that have just shown up rather than the good bacteria that are better established. Because they wash their hands more than most people, the hands of doctors and nurses have fewer species on them, but are more susceptible to invasion by bad species if doctors or nurses ever stop washing their hands.
4-Being exposed to a diversity of bacteria is beneficial and reduces allergy and autoimmune disorders, but figuring out just which bacteria matter is difficult and depends on human genotype (which genes you have). This is true now, but will seem even truer in the future.
5-In the absence of a full understanding of which bacteria are necessary, companies develop sprays with easy to grow (and not dangerous) bacteria that you can spray around your house. Some of those sprays are beneficial. Some are not. They all cost more than they should and are poorly regulated. Companies will also develop a device to measure the diversity of bacteria in your home and when your home (inevitably) fails to be sufficiently diverse, the same companies will sell you the “diverse microbiota” spray.
Image 2. Artist Kalliopi Monoyios (and co-author of SciAm’s Symbiartic Blog) wonders if one day we’ll find Bacterial Wipes on the shelves of the supermarket cleaning products aisle.
6-The beneficial microbes on your skin and in your gut prove to be composed mainly of a suite of individual lineages with intimate and specific co-evolutionary relationships with humans. Different human populations have different lineages of these main species, some of which are more beneficial and some less. The benefits of others depend on the circumstance.
7-Human bodies have many features that influence the specific lineages of microbes in different parts of our bodies. The appendix works as a reserve of beneficial species. The acidity of the stomach serves to filter out many pathogens. The nose and ears both exert a strong effect on which species live in them. The armpits prove to be an important organ associated with health and well-being as well as signaling identity of individuals or quality of mates among humans. In the armpits many bacteria are fed in high densities by specialized feeding glands.
8-At least three things about the relationship between bacteria and humans that are totally inconceivable (and seemingly ridiculous) today are discovered. Once discovered, they come to seem ordinary.
9-Several places in our homes that we imagine to be totally lifeless prove to have unique microbial species that evolved in those habitats since the construction of homes.
10-Microscopic species are exerting more control over our behavior than we imagined. Some differences in behavior among humans (in addition to the effects of Toxoplasma gondii) are accounted for by different exposures to microscopic organisms.
And here are five extra as a bonus (and because I simply cannot stop myself once I get started):
11-The common fungi in our lungs actually prove to have some benefit and are engaged in sophisticated relationships with the bacteria in lungs. The balance between lung fungi and bacteria is tenuous and easily disrupted.
12-Bacteriophages prove to be much more important in regulating the composition of bacteria on bodies than appreciated.
13-The excess of sweat on your feet evolved partially to feed an excess of bacteria that help to fight off fungi. People with stinking feet are less likely to get severe foot fungus infections.
14-Some of the very common species on human skin were not common a few hundred years ago. Some of the species common a few hundred years ago, when washing was rare, are now entirely absent from human skin except under unusual conditions similar to those where body lice are now found such as in homeless shelters.
15-I’ll leave this for your predictions about the bacteria, phages, viruses, fungi, and protists around us. What do you predict we will discover on bodies or in houses about the trillions of microbial cells living on and around us?
Having found myself a bit intoxicated by thinking about the future I also polled my microbially inclined friends (and one guy I don’t really get along with) for their thoughts on the future, which revealed that collectively my friends are even more wild-eyed (and largely optimistic) about the future than me.
Holly Bik: I predict our understanding of “microbial” health will be expanded to include contributions from important species that we ignore with current research approaches, such as protists, microscopic worms and arthropods. I guarantee that everyone is drinking and eating a LOT more microscopic worms than they probably think they are…not even your tap water is 100% free of these creatures. In addition, there are plenty of multicellular species that we know exist in the human microbiome. But we haven’t fully characterized these microbial eukaryote communities yet, and have very little understanding of how they may impact human health.
Nash Turley: Microbes cause epigenetic changes in their hosts making (the host’s) offspring pre-adapted to the same microbe community.
Jeff Leach: We will soon find that the way we treat our elderly will change. It wasn’t that long ago that all humans lived in fission-fusion societies – People coming and going, daily, weekly, multiple generations in one camp. No matter your age, you were continuously exposed to the larger metacommunity in your region – from the plants, animals, soil, water, blood, feces, hair, etc of everyday life. Today, our seniors are overmedicated and isolated – walled off from the larger metacommunity and its potential steady stream of health-giving diversity.
David Kroll: Microbiome variation results in different secondary metabolites produced, some immunogenic.
Jessica Green: See Jessica with her own two cents about the future of probiotic steering wheels: http://www.forbes.com/sites/bruceupbin/2013/03/01/yogurt-is-probiotic-why-not-your-steering-wheel/
Matt Shipman: I’m optimistic there will be meaningful progress in determining which species, or combinations of species, are associated with specific health issues; E.g., we know that diverse, robust populations of gut fauna help protect the GI tract from invasion by new species or from an overpopulation of an existing species (for example, C. difficile). But no one knows which species are most important, or what the population threshold is that separates “healthy” from “not healthy.” Ten years from now, I’m hoping we’ll know significantly more.
Ed Yong: Some quack will offer a bacterial “alternative treatment” that doesn’t work and in at least some cases does something horrible to someone.
Jenn Wernegreen: We’ll realize that variation in the gut microbiome underlies a wide range of mysterious diseases. We’ll spray beneficial microbes onto wounds, in order to promote a healthy immune response and accelerate wound healing. We’ll ditch Prozac, etc, and will work in balancing the microbiome to cure depression and other mental illness. The distinction between ecologists and medical scientists will blur – maybe disappear! We’ll grapple with ethical implications of microbiome research and treatment, including the outstanding question: “Who owns your poop??” Realizing that probiotics are serious, we’ll start regulating their content and activity.
Gaddy Bergmann: People will get literally sick and tired of eating beef from animals raised under industrial conditions. One reason will be that grain-fed cattle develop ruminal acidosis and dysbiosis, requiring both prophylactic and interventional antibiotics to survive. Because this practice has been recognized as a contributor to bacterial antibiotic resistance, people will finally take a more comprehensive approach to health, and stop subsidizing feedlots.
Rob Knight: Biofuels will be made from complex and robust communities of microbes rather than the monocultures that we attempt to use today. Architects will audit buildings using models for microbial characteristics as they currently do for airflow and power usage characteristics. We will be able to predict which drugs work for which people based not on their human genome, but rather based on their microbiomes, and in some cases we will be able to modify the microbiome so that specific drugs will become effective for specific people.
Noah Fierer: Our body odor is a product of microbial metabolites. Whether a person smells good (or bad) is going to be dependent on the types of microbes living on their skin and in their skin pores. Companies will be developing skin probiotics to alter body odor. Microbial ‘augmentation’ will replace lip/breast/butt augmentation as the new trend in improving perceived attractiveness. Fecal transplants will become the ‘next big thing’ in treating disease (real or imagined). The feces from individuals that have eaten a ‘pure’ diet (whatever that means) and have never taken antibiotics will go for top dollar on the black market.
Corrie Moreau: As the lines between medicine and evolution and ecology continue to blur, we will look to other social species for clues about how to successfully live in complex societies. Much can be learned from the long evolutionary history of social insects and their success in cohabiting with diverse beneficial and harmful microbes. Using natural systems like ants and termites we can manipulate and observe in real time how microbes spread through intricate societies to gain clues about how we should design our living spaces and when to quarantine the sick. We can learn a lot from other social organisms that have been highly successful both on the evolutionary (long-term) and ecological (short-term) scales in co-existing with a diversity of internal and external guests. One last thought it that we may find that having insects in our homes is actually important for seeding our living spaces with beneficial (and sometimes harmful) microbes. I can imagine a day where we call pest companies to add insects to our homes and not spray poisons all around them!
Jack Gilbert: We will all have a bioreactor (as Rob Knight says) made of complex communities in our houses, but not just for biofuel to power our car. We will be using these complex associations to (a) generate electricity, and then (b) convert electricity we don’t use into products that we sell back to the government. Imagine if we paid our taxes by turning part of our property or a broom closet in our house into a microbial fuel cell, and an electromicrobial acetate generator that generates revenue for local governments. Distributed chemical factories across the entire country!!! I also envisage a time when we enter a hospital and are given a microbial community drink to boost our protective gut microflora, possibly already impregnanted with IgA.
Note: Several of those who contributed ideas last on this list were able to see the ideas that came first. Several people noted that their own favorite ideas were already taken (in retrospect I shouldn’t have let myself go first, but I didn’t think about polling the community until after I wrote the piece) meaning that many of these ideas are not the rantings of individuals but instead the collective rantings of a number of biologists leaning into the darkness and, with the tentacles of their intuition out as far as they will go, guessing.