8 ms·

The Gut Microbes of African Hunter-Gatherers

103 points by rosser 13y ago

logfromblammo 13y ago
I am now curious to see what happens when you switch some of the Hazda group to an Italian diet, and some of the Italians to a Hazdan diet.
- Florin_Andrei 13y ago
  That would be interesting - but, as the article says, the environment where you're living is also important.
  - manmal 13y ago
    That's what they say, but I'm sceptical this is really the case. What do bacteria behind strong barriers (stomach acid, small intestine) care about external factors?
    - jonsen 13y ago
      Bacteria does not form spontaneously from nothing. You have to get them from your evironment. In fact there is a constant inflow.
      - Florin_Andrei 13y ago
        And they enter the intestine at both ends.
    - vacri 13y ago
      Basically everything you swallow comes out the other end. Not all bacteria are destroyed by stomach acid or other digestive juices. Bacteria are on most food - pretty much everything you eat is bringing new bacteria into your body. Some of them are benign, some can't handle digestion, some have to be dealt with by your body's immune system.
    - Mz 13y ago
      I will add that heat, humidity, sea level, air pressure and on and on likely impact your internal biology more than you think. Anecdotally, I moved back to Southern California as soon as I was able because my health is better in this climate than in other places I have lived. Also anecdotally: People who get stationed in Antartica have really bizarre, unexplained things happen to them sometimes, like their fingernails get a lot thicker and weird stuff like that. As I understand it, it is not just the cold. It is also anomalous in terms of height above sea level and other qualities. I don't know the details. It was just a snippet that stayed with me from an interview of a medical professional who had been stationed there and remarked on how this weird stuff happens and they don't even really have studies or any idea where to start hypothesizing.
    - Florin_Andrei 13y ago
      > strong barriers (stomach acid, small intestine) Just read this fun little page, and you'll re-think your stance on "strong barriers": http://en.wikipedia.org/wiki/Dysentery http://en.wikipedia.org/wiki/Dysentery
- marshray 13y ago
  That would make a great new reality TV show: Baby Swap!
- daemin 13y ago
  I'm sure if you had to survive in a different environment your gut flora and fauna would adapt to the new conditions given enough time. But unless you were forced to adapt with your survival at stake you'd just revert to eating whatever didn't cause you to become ill. This does remind me of an Anthony Bourdain No Reservations episode where they ate with the bushmen, and they gave Tony the "best" part of the hog - the anus - unwashed, uncooked. If nothing else then eating those parts of animals with all their attached microbes would introduce them to you over time. Tony did get violently ill for a few days after filming the segment.
  - logfromblammo 13y ago
    And that reminds me of a This American Life, where the show's producers were unable to actually uncover conclusive evidence that fried hog bung was being used as imitation calamari rings, but they did find in a blind taste test that you probably wouldn't notice if it were. So I wouldn't say it's the best part of a hog, but it certainly wouldn't be as awful as you might think. When prepared appropriately, of course. Nobody wants to eat raw swine manure as a condiment.
- tim333 13y ago
  Really you'd want to send a few Hazda to live in Rome for a couple of months and send a few Italians the other way. It would be a good experiment - I'd watch the reality TV show.
Mz 13y ago
Excerpt: In westerners, Bifidumbacterium is a microbe that many nutrition scientists thought was essential to good gut health, but it is almost completely absent in the foragers. Likewise, high counts of the bacteria Treponema have been linked to maladies like Crohn’s disease and irritable bowel syndrome. Neither of these diseases exist among the Hadza, but their guts contain abundant Treponema. As someone who has consciously and intentionally altered my gut so it would work closer to normal, to me, this suggests a lot of questions that I do not see being asked. 1) Perhaps modern diets are the problem and the biochemistry they foster rather than microbes per se. How can that be tested? 2) What actually causes "disease"? This implies to me that germs per se are not really the explanation. 3) I would be interested in seeing some data on biochemistry and cell structure of this group as compared to people with modern/Western diets. 4) I would be interested in seeing information related to genetics and how that impacts how their bodies deal with gut flora, etc.
- tokenadult 13y ago
  I'll upvote your set of questions and reply here rather than make my own top-level comment in this interesting thread. 1) The way to test a causal hypothesis is always, at bottom, to do a controlled experiment.[1] So we will tease out the effects of diet on different people by finding experimental volunteers, after institutional review boards approve the experiments, and subjecting the volunteers to controlled diets. This is very difficult to do, as almost all human beings eat when they feel like eating WHAT they feel like eating. Earlier human experiments on effects of diet have actually required the experiment subjects to live in the laboratory long-term, and to have every gram of everything they ate during the experiment measured exactly. Even at that, those experiments came up with few clear conclusions, perhaps because the experiments weren't lengthy enough or didn't include enough subjects for strong inferences. 2) Lots of different things cause lots of different diseases. Both poor diets and infections by microbes can cause some kinds of disease, each independently of the other. It is a fallacy of human thinking to think that there is only one true cause of disease.[2] 3) Yes, it would indeed be interesting to gather more data about biomarkers and tissues of people from more human groups, and especially so after experimental interventions as mentioned in my reply to your first question. It will take very detailed data-gathering to figure out what is going on at the causal level that makes the gut biomes different, and what the different gut biomes do. 4) Your "gut reaction" is correct that this study does not have what human geneticist Robert Plomin would call a "genetically sensitive design," such as what a study of twins[3] would have. The human behavior geneticists with whom I participate in a journal club during the school year have made me very sensitive to how much information is missed if studies of human subjects don't take into account genetic similarity and dissimilarity of the study subjects. Much more work needs to be done on this. My comment to a friend on Facebook after I posted this same story and friends started talking about it was "One tricky thing for you and me doing 'research' on this is distinguishing short-term effects from long-term effects. My life expectancy here in the United States is already a lot longer than that of most people in the world." It may be that you and I, with the health problems we have today in the United States, are still much better off sticking with our current diets rather than emulating the diets of hunter-gatherers in Africa. [1] http://escholarship.org/uc/item/6hb3k0nz http://escholarship.org/uc/item/6hb3k0nz [2] http://www.sciencebasedmedicine.org/the-one-true-cause-of-all-disease/ http://www.sciencebasedmedicine.org/the-one-true-cause-of-al... [3] http://www.hup.harvard.edu/catalog.php?isbn=9780674055469 http://www.hup.harvard.edu/catalog.php?isbn=9780674055469
shanev 13y ago
This is not surprising to me at all. Pathogenic bacteria linked to diseases such as Crohn's and IBS are only pathogenic if we get them later in life. When we get these bacteria in childhood, before the age of 7, they grow symbiotically with us and help ward off disease. Check out the book An Epidemic of Absence by Moises Valesquez-Manoff [1] if you guys want to learn more about this stuff. It's a fascinating account of a man who experiments with altering his gut biome to overcome Alopecia areata (total hair loss). The book is loaded with science and references a lot of other studies dealing with the gut biome. [1] http://www.amazon.com/Epidemic-Absence-Understanding-Allergies-Autoimmune-ebook/dp/B0061P2L5U/ http://www.amazon.com/Epidemic-Absence-Understanding-Allergi...
- tokenadult 13y ago
  I would ask my friends here on Hacker News to be cautious about taking the statements in that book at face value without a lot of careful follow-up.[1] And I write that, with chagrin, as a participant here who previously submitted an opinion piece by the author to Hacker News, where it reached the front page and sparked a lot of discussion. The claims in the book are very far from settled science, and many of the anecdotes have not been independently verified or replicated. [1] http://www.emilywillinghamphd.com/2012/08/autism-immunity-inflammation-and-new.html http://www.emilywillinghamphd.com/2012/08/autism-immunity-in...
  - coopermor 13y ago
    There's a small public biotech company Coronado Biosciences that just announced a trial to study their drug (pig whipworms) in autism http://ir.coronadobiosciences.com/Cache/1001185864.PDF http://ir.coronadobiosciences.com/Cache/1001185864.PDF. They have other studies in a couple different autoimmune diseases in various stages http://www.coronadobiosciences.com/research-development/pipeline.cfm http://www.coronadobiosciences.com/research-development/pipe... So we'll have some more data regarding this soon.
  - mtew 13y ago
    I found the book straightforward about how unproven the science is, and thought it did a good job of being clear about how speculative the theories are. Were there areas where you thought the book's claims were stronger than what is warranted?
ds9 13y ago
Somewhat related: presence or absence of diseases in an area may influence social and political systems, according to one theory (http://www.psmag.com/navigation/health-and-behavior/bugs-like-made-germ-theory-democracy-beliefs-73958/ http://www.psmag.com/navigation/health-and-behavior/bugs-lik...)
contingencies 13y ago
I wonder if there is any kind of feedback loop between long term gut flora makeup and taste preferences?
VeejayRampay 13y ago
A somewhat related and fascinating read is Dr Daniel Lieberman's "The Story of the Human Body: Evolution, Health, and Disease". He develops the concept of mismatch diseases and goes into a lot of details about evolution and diets across different eras and cultures (there's a part in the book dedicated to hunter-gatherers IIRC).
pistle 13y ago
Gut flora-related disease could have also exerted pressure on an insulated population leading to tolerance for elevated levels of bacteria which are observed as being related to unwanted symptoms in other populations. It takes more than a load of crap to tell the whole story.
davidw 13y ago
Here's how to make a startup out of it: you could sell exclusive trips to Hollywood types to Africa to get a hunter-gatherer biome "transfusion", proclaiming the various health benefits - "slimming! rejuvinating! all natural!". I think I'm joking, but who knows :-)
- tim333 13y ago
  Stranger schemes have worked. Travelling to those sorts of places and eating with the locals often leads to effective and rapid weight loss thorough slightly unpleasant mechanisms. On a more serious note my sister had IBS for a couple of years and it went away completely and permanently after visiting Indonesia - presumably some gut flora transfer thing.
tragic 13y ago
I might show this to my mother. She is of the opinion that no disease is sufficiently severe that it cannot be cured through large quantities of probiotic yoghurt.

103 points by rosser 13y ago

I am now curious to see what happens when you switch some of the Hazda group to an Italian diet, and some of the Italians to a Hazdan diet.

Florin_Andrei 13y ago
That would be interesting - but, as the article says, the environment where you're living is also important.
- manmal 13y ago
  That's what they say, but I'm sceptical this is really the case. What do bacteria behind strong barriers (stomach acid, small intestine) care about external factors?
  - jonsen 13y ago
    Bacteria does not form spontaneously from nothing. You have to get them from your evironment. In fact there is a constant inflow.
    - Florin_Andrei 13y ago
      And they enter the intestine at both ends.
  - vacri 13y ago
    Basically everything you swallow comes out the other end. Not all bacteria are destroyed by stomach acid or other digestive juices. Bacteria are on most food - pretty much everything you eat is bringing new bacteria into your body. Some of them are benign, some can't handle digestion, some have to be dealt with by your body's immune system.
  - Mz 13y ago
    I will add that heat, humidity, sea level, air pressure and on and on likely impact your internal biology more than you think. Anecdotally, I moved back to Southern California as soon as I was able because my health is better in this climate than in other places I have lived. Also anecdotally: People who get stationed in Antartica have really bizarre, unexplained things happen to them sometimes, like their fingernails get a lot thicker and weird stuff like that. As I understand it, it is not just the cold. It is also anomalous in terms of height above sea level and other qualities. I don't know the details. It was just a snippet that stayed with me from an interview of a medical professional who had been stationed there and remarked on how this weird stuff happens and they don't even really have studies or any idea where to start hypothesizing.
  - Florin_Andrei 13y ago
    > strong barriers (stomach acid, small intestine) Just read this fun little page, and you'll re-think your stance on "strong barriers": http://en.wikipedia.org/wiki/Dysentery http://en.wikipedia.org/wiki/Dysentery
marshray 13y ago
That would make a great new reality TV show: Baby Swap!
daemin 13y ago
I'm sure if you had to survive in a different environment your gut flora and fauna would adapt to the new conditions given enough time. But unless you were forced to adapt with your survival at stake you'd just revert to eating whatever didn't cause you to become ill. This does remind me of an Anthony Bourdain No Reservations episode where they ate with the bushmen, and they gave Tony the "best" part of the hog - the anus - unwashed, uncooked. If nothing else then eating those parts of animals with all their attached microbes would introduce them to you over time. Tony did get violently ill for a few days after filming the segment.
- logfromblammo 13y ago
  And that reminds me of a This American Life, where the show's producers were unable to actually uncover conclusive evidence that fried hog bung was being used as imitation calamari rings, but they did find in a blind taste test that you probably wouldn't notice if it were. So I wouldn't say it's the best part of a hog, but it certainly wouldn't be as awful as you might think. When prepared appropriately, of course. Nobody wants to eat raw swine manure as a condiment.
tim333 13y ago
Really you'd want to send a few Hazda to live in Rome for a couple of months and send a few Italians the other way. It would be a good experiment - I'd watch the reality TV show.

Mz 13y ago

Excerpt: In westerners, Bifidumbacterium is a microbe that many nutrition scientists thought was essential to good gut health, but it is almost completely absent in the foragers. Likewise, high counts of the bacteria Treponema have been linked to maladies like Crohn’s disease and irritable bowel syndrome. Neither of these diseases exist among the Hadza, but their guts contain abundant Treponema. As someone who has consciously and intentionally altered my gut so it would work closer to normal, to me, this suggests a lot of questions that I do not see being asked. 1) Perhaps modern diets are the problem and the biochemistry they foster rather than microbes per se. How can that be tested? 2) What actually causes "disease"? This implies to me that germs per se are not really the explanation. 3) I would be interested in seeing some data on biochemistry and cell structure of this group as compared to people with modern/Western diets. 4) I would be interested in seeing information related to genetics and how that impacts how their bodies deal with gut flora, etc.

tokenadult 13y ago
I'll upvote your set of questions and reply here rather than make my own top-level comment in this interesting thread. 1) The way to test a causal hypothesis is always, at bottom, to do a controlled experiment.[1] So we will tease out the effects of diet on different people by finding experimental volunteers, after institutional review boards approve the experiments, and subjecting the volunteers to controlled diets. This is very difficult to do, as almost all human beings eat when they feel like eating WHAT they feel like eating. Earlier human experiments on effects of diet have actually required the experiment subjects to live in the laboratory long-term, and to have every gram of everything they ate during the experiment measured exactly. Even at that, those experiments came up with few clear conclusions, perhaps because the experiments weren't lengthy enough or didn't include enough subjects for strong inferences. 2) Lots of different things cause lots of different diseases. Both poor diets and infections by microbes can cause some kinds of disease, each independently of the other. It is a fallacy of human thinking to think that there is only one true cause of disease.[2] 3) Yes, it would indeed be interesting to gather more data about biomarkers and tissues of people from more human groups, and especially so after experimental interventions as mentioned in my reply to your first question. It will take very detailed data-gathering to figure out what is going on at the causal level that makes the gut biomes different, and what the different gut biomes do. 4) Your "gut reaction" is correct that this study does not have what human geneticist Robert Plomin would call a "genetically sensitive design," such as what a study of twins[3] would have. The human behavior geneticists with whom I participate in a journal club during the school year have made me very sensitive to how much information is missed if studies of human subjects don't take into account genetic similarity and dissimilarity of the study subjects. Much more work needs to be done on this. My comment to a friend on Facebook after I posted this same story and friends started talking about it was "One tricky thing for you and me doing 'research' on this is distinguishing short-term effects from long-term effects. My life expectancy here in the United States is already a lot longer than that of most people in the world." It may be that you and I, with the health problems we have today in the United States, are still much better off sticking with our current diets rather than emulating the diets of hunter-gatherers in Africa. [1] http://escholarship.org/uc/item/6hb3k0nz http://escholarship.org/uc/item/6hb3k0nz [2] http://www.sciencebasedmedicine.org/the-one-true-cause-of-all-disease/ http://www.sciencebasedmedicine.org/the-one-true-cause-of-al... [3] http://www.hup.harvard.edu/catalog.php?isbn=9780674055469 http://www.hup.harvard.edu/catalog.php?isbn=9780674055469

shanev 13y ago

This is not surprising to me at all. Pathogenic bacteria linked to diseases such as Crohn's and IBS are only pathogenic if we get them later in life. When we get these bacteria in childhood, before the age of 7, they grow symbiotically with us and help ward off disease. Check out the book An Epidemic of Absence by Moises Valesquez-Manoff [1] if you guys want to learn more about this stuff. It's a fascinating account of a man who experiments with altering his gut biome to overcome Alopecia areata (total hair loss). The book is loaded with science and references a lot of other studies dealing with the gut biome. [1] http://www.amazon.com/Epidemic-Absence-Understanding-Allergies-Autoimmune-ebook/dp/B0061P2L5U/ http://www.amazon.com/Epidemic-Absence-Understanding-Allergi...

tokenadult 13y ago
I would ask my friends here on Hacker News to be cautious about taking the statements in that book at face value without a lot of careful follow-up.[1] And I write that, with chagrin, as a participant here who previously submitted an opinion piece by the author to Hacker News, where it reached the front page and sparked a lot of discussion. The claims in the book are very far from settled science, and many of the anecdotes have not been independently verified or replicated. [1] http://www.emilywillinghamphd.com/2012/08/autism-immunity-inflammation-and-new.html http://www.emilywillinghamphd.com/2012/08/autism-immunity-in...
- coopermor 13y ago
  There's a small public biotech company Coronado Biosciences that just announced a trial to study their drug (pig whipworms) in autism http://ir.coronadobiosciences.com/Cache/1001185864.PDF http://ir.coronadobiosciences.com/Cache/1001185864.PDF. They have other studies in a couple different autoimmune diseases in various stages http://www.coronadobiosciences.com/research-development/pipeline.cfm http://www.coronadobiosciences.com/research-development/pipe... So we'll have some more data regarding this soon.
- mtew 13y ago
  I found the book straightforward about how unproven the science is, and thought it did a good job of being clear about how speculative the theories are. Were there areas where you thought the book's claims were stronger than what is warranted?

ds9 13y ago

Somewhat related: presence or absence of diseases in an area may influence social and political systems, according to one theory (http://www.psmag.com/navigation/health-and-behavior/bugs-like-made-germ-theory-democracy-beliefs-73958/ http://www.psmag.com/navigation/health-and-behavior/bugs-lik...)

contingencies 13y ago

I wonder if there is any kind of feedback loop between long term gut flora makeup and taste preferences?

VeejayRampay 13y ago

A somewhat related and fascinating read is Dr Daniel Lieberman's "The Story of the Human Body: Evolution, Health, and Disease". He develops the concept of mismatch diseases and goes into a lot of details about evolution and diets across different eras and cultures (there's a part in the book dedicated to hunter-gatherers IIRC).

pistle 13y ago

Gut flora-related disease could have also exerted pressure on an insulated population leading to tolerance for elevated levels of bacteria which are observed as being related to unwanted symptoms in other populations. It takes more than a load of crap to tell the whole story.

davidw 13y ago

Here's how to make a startup out of it: you could sell exclusive trips to Hollywood types to Africa to get a hunter-gatherer biome "transfusion", proclaiming the various health benefits - "slimming! rejuvinating! all natural!". I think I'm joking, but who knows :-)

tim333 13y ago
Stranger schemes have worked. Travelling to those sorts of places and eating with the locals often leads to effective and rapid weight loss thorough slightly unpleasant mechanisms. On a more serious note my sister had IBS for a couple of years and it went away completely and permanently after visiting Indonesia - presumably some gut flora transfer thing.

tragic 13y ago

I might show this to my mother. She is of the opinion that no disease is sufficiently severe that it cannot be cured through large quantities of probiotic yoghurt.