The hologenome: How our relationship with microbes drives our evolution
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The Hologenome: How Our Relationship with Microbes Drives Our Evolution

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Is the secret to human intelligence lurking in our guts? Recent studies suggest that it might. Together, your genes and the genes of your microbes make up the “hologenome,” a single entity that is molded and shaped by our environment. Read on to learn how the gut microbiome impacts our evolutionary fitness and how it may have made our species what it is today.

hologenome
Microbes impact our evolutionary fitness and made our species what it is today. iStock.com/vitanovski

We can learn a lot from looking at paleontological evidence and studying the few remaining traditional hunter-gatherer cultures on Earth. From an ancestral or evolutionary perspective, it is increasingly clear that many modern chronic diseases are a result of a mismatch between our innate biology and our modern environment.

When we think about our biology and human evolution, though, we’re typically thinking about our genes, which carry our heritable genetic information. But what about the 99 percent of the genes associated with your body that are not even human? That’s right—while each human carries about 23,000 protein-encoding genes (1), the microbes living on and in your body have an estimated 9 million different genes (2). And these genes may be key players in determining the evolutionary trajectory of the host.

Before we go any further, though, let’s review a few basics of evolution.

Evolution 101

Every living organism has a genetic blueprint in the form of DNA. All of our physical characteristics are encoded by this DNA (and how it is expressed). When organisms pass on their genes in the form of DNA to the next generation, they are copied very precisely. On occasion, however, there will be a small change, or mutation, in the genetic code. These small changes ultimately produce genetic variation in a population of organisms. Sexual reproduction also provides a great deal of variation, with offspring receiving a mix of genes from both parents.

A particular mutation or variant of a gene can be harmful, neutral, or beneficial to an organism’s overall fitness. Those organisms that are most “fit” for their environment are more likely to survive, reproduce, and pass on their genes to the next generation. Organisms therefore tend to become more adapted to their environment over time. The various constraints of a given environment are the “selective pressures” that favor the survival and reproduction of one organism over another.

If two distinct populations of a given species migrate into different environments, they will experience different selective pressures and, over many generations, adapt to their respective habitats. If they are separated for long enough, their physiology may no longer allow them to mate with one another and produce viable offspring. When this occurs, we say that a new species has formed.

Since Charles Darwin published On the Origin of Species in 1859, abundant geological, paleontological, anthropological, molecular, and genomic evidence has provided support for his theory of natural selection. With recent knowledge about our microbial inhabitants, the picture has become a bit more complex.

The “Hologenome”

In 2007, Eugene Rosenberg and Ilana Zilber-Rosenberg introduced the concept of the hologenome. Far from contradicting Darwin’s theory of natural selection, the concept of the hologenome instead adds a layer of complexity that was not previously considered in evolutionary biology. It suggests that together, the host genome and the genomes of all of its related microbes make up the “hologenome” (3).

In other words, evolution does not act solely on your 23,000 human genes. Rather, it acts on the 9.02 million genes (both host and microbial) that are present in and on your body, as a single entity.

This is true for every multicellular organism on the planet, as symbiotic relationships with microbes are ubiquitous among eukaryotic organisms like animals, plants, and fungi. Every animal with a digestive tract has some form of gut microbiota that is unique to that animal. Similarly, plants are coated in bacteria and fungal microbes on their leaves and roots (4).

Did you know your body is part of a hologenome?

Microbes Significantly Impact Host Fitness

If you’ve read some of the other articles on my blog, the idea that microbes play a role in host fitness should be a no-brainer. Numerous modern chronic diseases are associated with disruption of the microbiota, such as allergies, autoimmunity, skin conditions, inflammatory bowel disease, thyroid conditions, diabetes, obesity, and others (5). The microbiota plays many roles in shaping the health of its host, including protection against pathogens, metabolism, detoxification, and immune and nervous system development (6). Microbes are also known to produce signaling molecules that influence human gene expression (7). In short, a healthy microbial composition typically results in a more “fit” individual.

In fact, microbes have been impacting host fitness for as long as multicellular organisms have been around. Mitochondria, the part of your cells responsible for producing energy, were actually once a free-living bacterium that was engulfed by a eukaryotic cell (a cell containing a nucleus) (8). This symbiotic relationship eventually became permanent. Similarly, in photosynthetic plants, the chloroplasts that are able to use light energy to make organic compounds are very closely related to cyanobacteria (9). Life as we know it would simply not exist without these microbially derived structures.

Microbes Increase Genetic Variation

In addition to directly impacting host fitness, the microbiota provides three novel modes of introducing genetic variation (10). Variation is absolutely crucial for the emergence of new traits and ultimately new species.

  1. Horizontal gene transfer: Unlike eukaryotes, bacteria and archaea are able to link up and share genes with one another. This means that even microbes that don’t colonize your body (like those in probiotics and fermented foods) can still potentially exchange genes with your resident microbes when they encounter one another.
  2. Microbial amplification: Changes in the local environment allow some microbial populations to flourish and other microbial populations to contract. This results in a shift in the collective microbial gene pool. We see this consistently with the influence of diet on microbial composition (11).
  3. Acquisition of novel strains: Encountering new microbes in the environment may result in a few strains of microbes that are able to colonize the host. This acquisition of new strains also means the addition of new genes to the microbial gene pool.

Are Some of Your “Human” Genes Microbial Too?

As mentioned in the previous section, horizontal gene transfer occurs frequently between microbes (12). For example, the Japanese are able to digest agar because they traditionally eat large quantities of seaweed. The marine bacterium Zobellia galactanivorans colonizes the surface of marine plants, feeding on the agar. When the Japanese routinely ingested this marine bacterium on raw seaweed, it “shared” its genes for agar-degrading enzymes with their resident gut bacteria (13). In this way, the microbes present on the foods that we eat may very well “educate” our gut bacteria by sharing the genomic information necessary to digest it.

So microbes can share genes with each other. But what about human cells? Can microbes share genes with us? Recent studies suggest that they can, and in fact, it occurs quite frequently. A total of 145 genes commonly thought of as “human” genes can be attributed to horizontal gene transfer. Most of these genes come from bacteria, but some come from viruses or yeast (14). Considering the fact that only a small percentage of microbes on Earth have been identified (15), and an even smaller percentage have had their full genome sequenced, it’s quite plausible that many more of our genes will be shown to have microbial roots in the coming decades.

Microbes: Creators of New Species

Microbes also influence the emergence of new species. In 1989, studies on fruit flies showed that splitting a fly population and raising some on a molasses medium and others on a starch medium resulted in distinct mating preferences. The flies grown on molasses preferred other “molasses flies” and the flies grown on starch preferred other “starch flies” (16). This is important because mating preference is considered to be an early event in the emergence of new species.

More recent studies followed up on this finding and found that antibiotic treatment eliminated the diet-induced mating preference. Subsequent recolonization of these antibiotic treated flies with the bacterium Lactobacillus plantarum reestablished the mating preference. The researchers found that L. plantarum was able to change the levels of sex pheromones released (17,18).

The microbiota also influences whether an offspring is viable after conception. Recall that according to the biological species definition, two groups of organisms that cannot interbreed with one another and produce viable offspring are considered to be separate species. A study on wasps found that when recently diverged wasp species were crossbred, all of the hybrids died during the larval stage. Antibiotic treatment rescued the survival of the hybrids, suggesting that their symbiotic microbes played a role in hybrid mortality (19).

Host Genome Shapes the Microbiota

While your environment, early-life experiences, and diet all play a major role in shaping the composition of your microbiota, your genes also play a role.

Across the animal kingdom, microbial community composition parallels phylogeny (20). This means that animals that share a more recent common ancestor and are more closely related to each other on the evolutionary tree of life also tend to have more similar microbiotas, even when maintained on the same diet (21).

Genetic variation can also explain differences in the microbiota within a single species. Single nucleotide polymorphisms (a change in one base molecule in the DNA) and copy number variations (the number of a certain gene that you have) can explain differences in the microbiota (22). Furthermore, in humans, identical twins have a very similar microbiota composition (23), and microbial composition tends to correlate with ethnicity (24).

So how exactly do your genes shape the community of microbes that inhabit your gut, skin, lungs, nasal passages, and other areas of your body? It turns out that hosts have developed several means of regulating which microbes can colonize and which cannot. One is encoding genes for antimicrobial peptides, which are secreted at mucosal surfaces. These small proteins inhibit the growth of certain microbes over others (25). Hosts also produce microRNA molecules that can enter bacteria and regulate bacterial gene expression, growth, and survival (26).

Expansion of Diet and Increased Social Behavior Fueled Human Evolution

Hopefully you’re still with me, because now we get into the really interesting stuff: how the hologenome played a role in the evolution of our species, Homo sapiens. Scientists have long speculated about the forces that were responsible for the development of human intelligence. Two factors seem to stand out in relation to the hologenome: an expansion of hominid diets and an increase in social behavior. Let’s look at each separately.

Meat, starchy carbohydrates, and the advent of cooking have all been associated with expansion of the human brain (27,28). The transition to bipedalism (walking upright on two legs) allowed for the carrying of foraged materials from great distances, diversifying the diet of early hominids (29). It also made it easier for our ancestors to track and pursue large animals.

This diversification of meat and plant foods necessitated a similar diversification of microbes able to extract nutrients from these new energy sources. A study published just this month found that humans have a faster metabolic rate than any other primate, which likely fueled the evolution of larger brains (30). This increase in metabolic rate was likely at least partly due to changes in microbial composition, as microbes have been suggested to play a key role in determining host energy expenditure (31).

Social behavior in primates is also thought to be a critical factor in the evolution of human intelligence (32). Access to microbes may have been a driving force in the evolution of animal sociality, since microbes confer many benefits to the host (33). Social behaviors like grooming, kissing, and sex increased the transfer of microbes from one organism to another. Studies in social mammals have found that development of the forebrain and neocortex in social mammals depends on signals from the microbiota (34), and germ-free mice that lack a microbiota also lack social behavior and show deficits in social cognitive abilities (35).

What’s in It for the Microbes?

All right, it’s clear that we benefit from the microbes in our guts. But what’s in it for the microbes? As mentioned in the previous section, increases in host social behavior allow for enhanced microbial transmission between hosts. Living in symbiosis with a host also provides microbes with an environment rich in nutrients. Recent evidence suggests that the microbiota might even shape host feeding behavior (36), making you crave the very foods that feed particular species in your gut (stay tuned for an article on that topic).

It’s also important to keep in mind that evolution does not have an end goal. Historically, Earth was completely microbial for 2 billion years before eukaryotes entered the scene. Simply put, eukaryotic evolution has never seen a period without the presence of microbes. An ancestral approach to health would be therefore be remiss without considering the role that microbes and the hologenome have played in the past and the role that they will play in shaping the future of our species.

You might be left wondering: is our modern diet and overuse of antibiotics messing with evolution? It’s certainly possible. A recent study performed in Dr. Justin Sonnenburg’s lab at Stanford showed that in mice, a diet low in fiber caused dramatic changes in the microbiota that were reversible within that generation if fiber was reintroduced. Over several generations, however, a low-fiber diet caused an irreversible loss of microbial diversity (37).

Cultivating a healthy community of microbes with a nutrient-dense diet is not only important for your own health, but might also be important for the health of your great-great-grandchildren!

Now I’d like to hear your thoughts. Had you ever heard of the hologenome? What was most surprising to you? Let us know in the comments section!

39 Comments

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    • There are a number of pre-biotic and probiotic products on the market. You can do a web search and then experiment with some of them.
      For those interested in a more complete understanding of the hologenome and its importance, consider reading The Microcosm Within: Evolution and Extinction in the Hologenome.

  1. Hi CHRIS,

    Such a very informative blog about how our relationship with microbes drives our evolution. You mention all the thing which make very easy to understand how it work.

  2. A couple of small factual points that may help clarify:

    Its not “your genes and the genes of your microbes”. The entire set of genetic elements comprise “you”. There is no ‘you’ without the microbes. The genome we used to think of as the ‘human genome’ is really an apobiont, or scaffold genome.

    And also, FYI, It was not the Rosenbergs who first introduced the Hologenome theory in 2007. Richard Jefferson (me) a reasonably prominent molecular biologist at the time, speaking at a major symposium at Cold Spring Harbor in 1994, (followed in 1997 at another international meeting in South Africa) developed the theory in its entirety. The lecture at Cold Spring Harbor was published as a video collection by Cold Spring Harbor press, and his lecture is on YouTube. Check out Jefferson’s bio on Wikipedia, the Hologenome article there, or the cover article by Carrie Arnold in New Scientist, January 2013. And Jefferson’s blogs explain how modulation of vertebrate steroid hormones by enteric bacteria informed the development of the theory by providing critical evidence that microbial populations controlled levels of hormones that influence reproduction and mate choice.

    • Very recent genetic research indicates that genes can actually learn and remember so past solutions can be used if once again required. Instead of evolution being thought of as a dumb trial and error process now it looks mathematically analogous to the most elegant of problem solvers, the human brain.

  3. No, I’d never heard of the Hologenome, but have been familiar with the importance of gut microbiata for some time, especially as described so well in Jiulia Enders’ book “The Gut”.
    What I especially learned was the importance of feeding all those little critters properly, especally as there are far more of them in and on our body than our own cells.
    Thank you for your addition to this whole growing area of information – very helpful to my work as a therapist helping those with chronic and autoimmune conditions such as MS.

  4. Chris, would you consider learning the Five Biological Laws that Dr. Hamer discovered, commonly called German New Medicine? They will give you even more info about the beneficial role of microbes…..from a different perspective.

  5. What about this? Humans and their Microbes may just keep evolving so that those who do manage to do well on the current SAD diet will live longer to pass on their genes (similar to the lactose tolerance gene event hundreds of years ago) and in the end hamburgers and fries will be exactly what the perfect diet will be for them. Stress and anxiety will be what makes them thrive. The rest of humanity will die young or become infertile and not be able to pass on their genes. Maybe this change in diet and lifestyle is just another test on the human genome and a trigger for the next round of human evolution? In the end we can’t go back to the past, we must move forward and as mentioned above, evolution has no end game or judgement, it just keeps moving on…… for those of us already here and suffering, all we can do is change our diet and lifestyle, try and pass it on to our children and hope the above does not happen.

    • But you have to ask, how will this new generation thrive? If the body is thriving on stress and bad food, you have to look at how it might manifest. If this new gen is physically incapable of getting around ( just an idea) how will they mate? Who will serve their basic needs? If there is any kind of economic collapse, where say electricity is less available or restricted, how does the new gen deal with that?

      Think thru some iterations and it all becomes very interesting.

      • Hmm, maybe the ones that thrive won’t get fat, they won’t find it hard to get around, they will be able to pass on their genes and won’t get sick in later life. Unfortunately, people are becoming sick today younger and younger, maybe they will become infertile and therefore their genes will not be passed on……only time will tell. I for one am heading down the path of the natural diet and lifestyle changes, that this website promotes, hopefully my children will too and their children, and they will meet other peoples children who feel the same way and voila! In the end evolution will decide and I am hoping that if enough of us make the same lifestyle changes that the decision will benefit the human race as we see it. But evolution does not have an opinion it just follows the changes and moves on….

        • Yes the point is that we didn’t have enough selective pressure so far, there should be a great pressure to induce changes. But it would be a double edged sword because we have boundaries of change. Our microbiome may change fast but it interacts with our genome and epigenome and if they don’t allow a certain microbial pattern to thrive right away we don’t see an adaptation. Moreover epigenome flexibility is bounded by genes themselves, I can turn on and off a gene that doesn’t exist. And the mutation rate is mostly fixed, meaning that we could change at X pace for slot time. We have succesful examples of evolution at work (chimps to humans), but we also have mass extinction examples. Dinos should have adapted to their new environment but they didn’t because their features were not able to deal with that and there has been no chance to change it. Anyway, everything is possible…

          • I did an error..I meant ” I can’t turn off and on a gene…” moreover we have a shifting target, because every day we put new engineered stuff into our mouth

        • Yes evolution has no opinion, but you and many other sdo and you all seem to miss the point of the science. You have no real way of knowing IF you are altering in any way, your own genome let alone your microbial biome…but human arrogance, and hubris tells us we are the only captain of our ship, but the science says otherwise. No matter how many kale and butter smoothies you down and no matter how often you bear crawl none of it may be doing anything but provide you some relief from a prior life of poor dieting, etc… You may have already effected your “biology” enough that you’ve reset it, but in a direction you have no idea of, or how to reset.

          Nor do you have any idea what traits you will pass down. Period. Becuase you could already be a conduit of traits startedtwo or more generations before you that you have not reset at all. But have – maybe due to poor dieting, etc, then a scramble to fix it – only set those traits in stone.

          If evolution has no opinion, and we are products still under its control, we have to grasp that unless we go thru serious gene altering modalities we are only gaining momentary relief and our opinions of what we do, of our alleged dietary virtues is like spitting into the wind.

    • Would you like to be the one to test if you can tolerate the western diet or get sick? How can you know if the partner you choose will be the one with the more resistant genes? If you’ll be able to recognize who actually carries the more resilient hologenome, would you take personally care to avoid that people only mate with the “right” ones? If not, even if it was possible to do well with the aforementioned diet (I doubt it unless we turn into something else a farcry from humans), there’s little selective pressure until you’ll be able to mate and get sick only in late adulthood, i.e. the case you see every day around. Sorry, I’m not going to play the russian roulette and I prefer to choose a safe template, safe for me and for my planet.

      • Interesting observation. There is science to back it up. For a number of years studies indicate the less an animal eats, so long as essential nutrients are adequate, the longer it lives. More recent work indicates that the controlling factor is not total calories but total carbohydrate calories. The Sweet-Sixteen gene (DAF-16) monitors serum glucose and IGF-1 and adjusts cell replacement rate. The lower these two factors the less frequently cell replacement takes place. Each cell replacement is recorded by a progressive shortening of the telomere on the end of the chromosome. With a finite number of cell replacements available the less frequently they take place the longer it takes to run out of replacements. SAD is high carbohydrate relative to the previous generation’s diet. Models of species survival show how this variable responding to environmental conditions will optimize species survival. You can see lectures on the subject by Cynthia Kenyon on You Tube.

    • I thought that too. What I haven’t decided is whether the changes in behavior that accompany the shift will end up making us better or worse. The sad diet makes people more violent and less sociable. Or maybe the antibiotics will prevent any real change by continuing resterilising the gut

  6. I recently read the Sonnenburg’s book “the Good Gut”. It was fascinating regarding some of the experiments they had done. As with most studies though people tend to focus in on one area. When you look at environment there is more to it than just food. They also need to look at where things like sleep and exercise can alter the microbiome. A healthy person has a good combination of these and a good diet.

  7. 2 billion years of microbial life…then the eukaryotes…then everything else.

    The expression that we are our biology has long passed the point of no return for me. We are microbial life…in our entirety.

    2billion years of microbial life. Microbes everywhere. 2 billion years. It’s all about the microbes and they are doing as they please…to think you can alter this evolutionary past with some pickles and pro/prebiotics in a kale and butter smoothie strikes me as the height of human arrogance.

    Microbes are gonna do what they do…been doing it for how long now? All without our notice…they got one nice lead on us puny humans. Plus we haven’t found most of them yet, or the many other places they inhabit.

    • the description I read a few years ago was “gene survival machines” The genes are immortal but not us as individuals

      • Yes. And it’s that very idea that can throw many monkey wrenches in the Intelligent Design crowds ideas.

        But it goes beyond the genes for me, to all these ever smaller life forms amassing and forming the larger ones that we humans deem The Chosen ones, in our religious and quasi religious ideas about life and its origins and purposes.

        The big debate over human consciousness, did it emerge, or was it purposely instilled – will be solved, or at the very least be better discussed by looking at microbes.

        For me it emerged…had to…much like a fast motorcycle emerges when all the parts are assembled. No one part gives the bike its speed…so you can’t pinpoint the exact reason/cause by looking at the parts, which is what humans have been caught up for so very long. The brain for instance, is viewed as this solo organ…but its not.

        Fascinating all of it.

  8. The latest studies of our hologenome had exposed the abysmal disconnect of the actual medicine drug/symptom oriented, with his hysterical addiction to sterile mediums, and their overuse of oral antibiotics that alter the gut’s ecosystem.
    It exist any possibility that this wrong medical approach could be rightly corrected in the near future for the benefit of all of us?

    • In an ideal world, one would hope so. In the universe in which we live, very little chance. Too much $$$$ in play for the “powers that be”.

  9. This was a great thought provoking article. Thank you. I have been trying different foods to determine an ideal balance for myself and my bacteria and your article makes me feel like it is a necessity to do so for my and my future generations wellbeing.

    • Ah, the ideal balance…a current meme for sure…but what does it really mean? How would one truly measure it, macro and/or micro? Take veganism…most people tend to feel really good on the diet – then after time, many, way more then is ever reported, feel less then good, but don’t blame the vegan diet, but themselves. So they dig in ever deeper, maybe go all raw, or microbiotic, etc…

      Because what might make you feel better for a time is not what your microbes need – but they can’t talk to you directly and tell you that food X is making you ill. Or that you need food Y which is off the list of acceptable vegan, etc diets.

      This is all new and emerging science and lay people like us need to take it slow and be logical and skepticle…and deem health plateaues, or simple changes as ideal States.

  10. What an excellent article clearly explaining how much more complex and flexible are what we have thought of as the genomes of living organism This contrast with the simplistic Neo-Darwinist view which would have us believe we are the result of the interaction of 23,000 simple genes affected only by random accident and natural selection. The difficult concept of Phenotype more closely describes an organism; the classical genome comprises only a small part of the phenotype and does not even explain basic species behavior in many cases. By example the Wolf and Dog genomes are virtually identical yet their fundamental behaviors are starkly different and breed true. The Wolf phenotype was quickly modified while the genome remained constant to the point that the dog can understand and respond to hand-pointed directions by a human, something a Chimpanzee and almost all other animals cannot do. The flexibility of the phenotype is a stable highly flexible system. In addition to the basic genome it includes the symbiotic biome, the heritable experiential programming of genes and additional co-factors transmitted along with the genome during breeding. As eminent geneticist Eva Jablonka stated a few years ago, the genome is not a run-away cart (random error followed by natural selection), it is led by the epigenetic horse. Since that time the major influence of the symbiotic Biome has come to light and gained credibility so that horse is now far more in charge then even she once believed. So much of us is in the biome because species survival would be at grave risk if rapid changes could not be made under the control of something other than the risky random mutation of the genome, something set in stone. But since it is so easily changed our bad behavior can cause problems. Inappropriate food is one example.

  11. Really interesting. We talk about co-evolution and we have to take into account our genome and microbiome together working symbiotically in both ways, in a complex symphony that can be easily broken in our modern environment. Grains and processed stuff in general wreak a bad havoc in our microbiome, as already enlighted by the Spreadbury’s excellent paper a while back. Of course there are many other things that disrupt either our gut or our microbiome with the mandatory feedback on the other, setting off a loop not easy to be fixed.
    Abother observation is: ok, we can harbor new bacteria introducing a new food, but having such bacteria in our gut that thrive on that food is not a sufficient condition to say that we are adapted to that, because we have to see if and how those guys are supposed to be there, and if their metabolism is going to peoduce good stuff like butyrate or instead nasty byproducts that trigger inflammation.

  12. I keep reading about the “remarkable” Japanese ability to digest seaweeds, as if eating sea vegetables were unique to the Japanese. It’s not. Many, if not all, coastal populations have included sea vegetables in their diets for millennia. In East Asia, the Chinese and Koreans also used sea vegetables for the same timeframe. Dulse was a popular wildfood in the British Isles and among New England settlers. Sea vegetables were consumed by coastal Native American populations on both Coasts. They have also been used in Mediterranean cultures for likely thousands of years, and by Pacific Islanders since those areas were colonized. So, I am curious as to what is supposed to be unique about the Japanese consumption of sea vegetables? As resourceful as humans have been in exploiting environmental nutrient sources, it would have been odd if they had ignored such a rich and easily-harvested resource as sea veggies.

    • Couldn’t resist having a quick look at the paper referred to in the text “Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota” – The idea of shipping in from bacteria a ready made metabolic solution for dealing with seaweed was fascinating and somehow compelling. It demonstrates a method by which a species could quickly respond to environmental changes rather than relying on piecemeal random mutation eventually coming round to a solution. However, the paper does not stress the uniqueness of the Japanese – It just compared the Japanese to N. American population (perhaps not the world’s biggest seaweed eaters?). As you point out, it seems many coastal populations appear to have the ability to deal with seaweed. You could speculate they gained the ability in the same way suggested by the paper, and the fact that it is so wide spread, sort of supports the proposed bacterial mechanism rather than each population having their own random mutation route.

      • Yes, it absolutely makes more sense, and is the simpler explanation (usually a good indicator in science) that the microbes were there to “inoculate” coastal peoples, rather than myriad mutations to accomplish the same thing. BTW, I am a great fan of sea vegetables. I’ve always found the flavor irresistable, whether dried, in soups, wrapped around sushi, or any other way. It’s nice that they are now more easily obtained, since the “seaweed snack craze” has taken hold.

    • I am guessing that the study included the Japanese, who are politically closest to the West.

    • Very good point! I totally agree. Maybe not “igored” but simply put aside and in favor of chosing other things. (This is not too hard to imagine when considering how our “food choices” are manipulated by advertising, etc.)
      Thank you Chris for this article! The information you present can open our eyes to select foodstuff that’s been there right in front of our eyes! (I’ve lived on the Pacific Coast and saw the seaweed everywhere…on the beach and also for sale in the food stores!) – It still can be bought and I will start to include it in my diet.
      In that respect, the Justin & Erica Sonnenburg’s book “The Good Gut” was also an eye-opener, especially their ref. to the MACs = macrobiota accessible carbohydrates. (“Eating more MACs can provide more nurishment to the microbiota, help gut microbes thrive, and improve the diversity…” p.112)

  13. You forgot to mention the inoculation that occurs at birth.. Just saying because one that seems very obvious to me, It almost seems that our cravings are entirely due to the demands of microbiota. What else can it be anyway? Only through a conscious voluntary act of shifting can we modify our eating habits. But considering the limited choices of certain class of people, we are left with all the chronic conditions that drives the health industry. This should be taught in school early in life so that people can understand what it means to be healthy and how it can be achieved.

  14. Fascinating info…thanks for putting this together in a way that is easily understood

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