A Diet for the Human Holobiont.

 

A picture taken at an open-air market near Florence in 2015. As you see, overall, people are not fat in Italy. But that doesn't mean we don't have our share of obesity problems. 

The human holobiont is a wonderful machine that can do many things in many different ways. It has a "dual fuel" system that allows it to subsist on two main kinds of foods: one his carbohydrates, the other is fat. You probably know something about how switching to the fat-based metabolism can improve your health and reduce your weight. That's called the ketogenic, or "keto" diet. 

I won't go into the details. I just wanted to tell you that I am experimenting now with a relatively new version of the ketogenic diet, called sometimes the "pseudo-fasting" or "Fast-Mimicking Diet," developed by prof. Valter Longo presently at the USC university but, incidentally, born in Italy. 

The story of this and other similar diets is long, but the basic concept is always the same: you tend to mimic the way the human holobiont machine would work in its natural environment. There, it wouldn't normally have a 100% daily supply of high-energy content carbohydrates, from Corn Pops to ice cream. And, clearly, this kind of diet is not good for us for many reasons. Not only it makes us obese, but it also generates diseases such as diabetes, high blood pressure, high blood cholesterol, all that. It is called the "Metabolic Syndrome"

Recognizing the problem, led to several proposals to solve it: diets, mainly. One is the "paleo diet," others involve intermittent fasting. In all cases, you try to reduce the amount of carbohydrates you eat. The idea is to exploit the capability of your body to switch to use fat as an energy source. It is a different concept than that of the "standard" diets, which often consist of reducing calories without worrying too much about what kind.

At the basis of the ketogenic diets, there is the idea that you mimic a condition that your ancestors would normally encounter in their lives: that of running out of food. We store energy in the form of fat just as a precaution against that event. When we don't have enough carbohydrates, we can switch to fat and that makes us leaner and fitter. Our body "understands" that there is a problem and it moves to remedy it. Under the ketogenic regime, you are on the prowl. You are searching for food. 

So, how is the pseudo-fasting working? I can tell you about my personal experience. I am not obese, just moderately overweight. The main reason I am trying this diet is to reduce my blood pressure without using pills -- and all the typical problems you have as you age (I am 68): gastro-esophageal reflux syndrome, sleep apnea, pre-diabetes, if you are over 50 you know about that.  

The version of diet that I am following involves a reduced food intake: 40 grams of nuts and about 400 grams of vegetables per day -- plus a little olive oil (a must for Italians!). As I am writing this post, I am on the 4rth day of a 5-day cycle. It seems to work: I can see that I am in the ketogenic mode using "keto sticks." I've lost about two kgs, so far. Not much, but it is something, and I am still halfway through the cycle. And my blood pressure is going down, nothing dramatic, but a little, yes. 

What I think is interesting is how the pseudo-fasting diet is a relatively easy diet to follow. In the past, I had tried the alternate fasting diet, you fast one day and you eat normally the other. It is fine, but I found it a little harsh. At least for me, pseudo-fasting was much easier: a little hungry the second day, but no problems the other days. The beauty of the idea is that you don't separate yourself from the rest of your family at mealtimes. You eat with them, although, of course, you eat very little and food of low nutritional value. 

I also think it is important that this diet is not made to punish you by making you hungry. We tend to think that our ancestors were primitive brutes and would go hungry all the time. No, not at all. As Chuck Pezeshki explains, humans are social animals and tend to share food. There must have been times harder than others, but hunger must have been rare, just as over-abundance. Hunger and obesity are maladies of what we call "civilization." So, I think the pseudo-fasting diet does mimic something that our ancestors would experience: periods of scarcity where they had to cope by being smart and efficient and make the best use of their (our) dual-fuel metabolic system.

Then, of course, I am experiencing the same sensations that I had with the more conventional fasting. All sensations that are part of the evolutionary tools you have inherited from your ancestors: you feel more tired, but also more alert. You tend to conserve energy, but you are ready to go into running mode if you see a potential steak in your hunting range. Or, more likely, edible berries not so far away. A peculiar sensation is the different range of vision. Somehow, I tend to detect things at a larger distance, noting details that I don't normally note. I don't know if this is common, but it makes sense: if you are on the prowl, then you have to be alert for any possible food source, even a distant one. 

Then, of course, when you are on a diet, you tend to dream of eating good things! But I figure that it is normal. I woke up this morning while dreaming of caviar and champagne. Yes, like James Bond and Vesper Lynd in "Casino Royale." A diet that gives you this kind of dreams must have something good in it!

So, how does that relate to the concept of holobionts? Well, it is because you shouldn't forget that what keeps you alive is a large number of little creatures inside your cells: the mitochondria. They are the source of energy for everything we do, but, remarkably, they don't share your genetic code. Their DNA is just theirs, you inherit them from your mother and not from your father. For some reason, when the female ovum is fecundated, the mitochondria carried by the male spermatozoa are destroyed and disappear forever. So, mitochondria are creatures living inside the human organism. They are a perfect example of symbiosis: they couldn't live without you and you couldn't live without them! That's how holobionts function. 

And we keep going. Who knows? One day we could find a way to stop the obesity epidemic that's making so many people sick and unhappy in the world. Onward, fellow holobionts!

To go more in-depth, do read this wonderful post by Chuck Pezeshki. And thanks to Dr. Alberto Santini for having placed me on the pseudo-fasting track!

The Holobiont Explained. What it is, how it functions, how it came to exist

 

 

In this clip, I do my best to explain the concept of "Holobiont," popularized first by Lynn Margulis in 1999 with her book "Symbiotic Planet." It is a powerful concept to explain how we relate with our surroundings: the whole ecosystem and our fellow human beings. If we ever arrive to assimilate this idea into the general way of thinking, we have hope to stop the aggression on everything not human (or considered not human enough) and live in peace on this planet.

Your Skin Microbiome Loves you. Don't Kill it!

 

Good news for us, holobionts! Nature has made available for free an entire issue dedicated to the microbiome of the human skin. Plenty of interesting data about all the members of the human holobiont: the mammal and the bacteria together. 

 

There are over 1000 species of bacteria for every single mammal, and these bacteria are doing a lot of good things for the whole biont, including protecting us from external infections. One thing they say is:

"researchers have uncovered evidence of extensive communication between bacteria, skin cells and immune cells. These interactions help to reinforce and repair the barrier formed by the skin, bolster the body’s defences against infection and tamp down excess inflammation."

So, wash your hands only when it is really necessary and don't use aggressive chemicals: otherwise you'll weaken your resistance to bad microbes. Your skin microbiome loves you, don't kill it!

 

Here is the link to the issue and, as always, onward, fellow holobionts!

Holobiont Science: Sometimes a Little Vague, but Always Interesting

 

Holobiont science is sometimes a little vague, but always interesting. Here is an example.In this paper, http://www.zoologia.hu/list/Why_infest.pdf, Rozsa and Apari argue that head lice in humans is a useful symbiont because it generates an immune response that helps protect humans from body lice, which can be dangerous as vector for harmful bacteria. (the photo above is from the paper)

 

It is an interesting story where you learn that there are at least two types of lice living with humans. And you learn that apes have only one kind, probably because they are uniformly hairy. Rozsa and Apari go on suggesting that the "touching heads" human habit has the specific purpose of diffusing health lice in such a way to spread the immunity to body lice. Apes, they say, don't touch each other's heads because they don't have such a need. 

 

Which is, as I said, very interesting, but is it true? Honestly, it gives you the idea that the authors are piling up one hypothesis after the other, none of them being really supported by data. For instance, in the places where I live, there is no habit of touching heads as a form of salutation or an expression of friendship. Then, are we sure that apes touch heads less frequently than humans do? I don't think we have solid statistics on that point. Besides, why are body lice dangerous, but not head lice? One more mystery of holobionts! 

 

But it is nevertheless a nice idea that adds a little more to the complexity of the idea of holobionts. And the picture that illustrates the paper (in lieu of non-existing data) is truly charming. Two distinguished professors exchanging lice. Wonderful!

The Chimera and the Holobiont

 

This is a rather ambitious project of mine where I examine a subject I have been working on for a long time, the Chimera myth, from several viewpoints: myths, lore, history, symbolism, and more. But I also try to take a look at the Chimera from the view point of a beloved concept of mine, that of the "Holobiont."

You probably already know that the term "chimera" has a specific meaning in biology: an organism having more than a single set of genes. But these creatures are normally considered some kind of freaks, the result of the work of some mad scientists or the like. But chimeras (in the biological sense) are just a special case of "holobionts" -- with holobionts defined as creatures composed of organisms of different species. And that's clearly the case of the Chimera. 

In this clip I try to outline how the concept of a multiple organism, a holobiont, is a general concept in ecology, but also in fields such as memetics, where "memes" act indeed as holobionts, having "sex" with each other and exchanging information to create new memes. Or new myths, it is the same thing. Or the whole ecosystem. In the end, we are all chimeras!

I hope you may find the clip interesting. It was not easy to make it: I am not a professional and I have to apologize if it is a little rough at some moments. But I did my best. I have also to thank the Frilli Gallery in Florence and Ms. Clara Marinelli for having allowed me to film their full-size replica of the Chimera of Arezzo.

The Secret of Holobionts

 

"Braiding Sweetgrass" is a wonderful book, the kind that's best digested a few pages at a time. (h/t Erik Assadourian). In it, the author, Robin Wall Kimmerer, happily moves back and forth from the uses of her Native American ancestors and her knowledge as biologist. She never uses the concept of "holobiont," but the book teems of holobionts on almost every page.

 

I am about halfway through it, and the book remains full of surprises. Here is what I read this morning, while drinking my coffee. It is about how the ancient Native Americans had found a way to optimize their plots of land by planting together three different seeds: corn, beans, and squash, poetically referred to as the "Three Sisters." Kimmerer goes on describing the details of exquisitely intricate ways in which these three species collaborate with each other, maximizing the supplying of nutrients to all three. She says.

 

"It’s tempting to imagine that these three are deliberate in working together, and perhaps they are. But the beauty of the partnership is that each plant does what it does in order to increase its own growth. But as it happens, when the individuals flourish, so does the whole. In reciprocity, we fill our spirits as well as our bellies."

 

And that's the true secret of holobionts.

On the Importance of Having Limbal Rings. The Evolution of Humankind

 

 

 

 

This short movie, Vikaari, has recently appeared on the "Dust" site and I think has several interesting features, relevant to the concept of holobionts. 

 

It is very well done as a movie, although it is deeply contradictory in many aspects. For one thing, it is a narrative disaster. First, the movie tells you that the Vikaari, children born without a visible iris in the eyes, are good people, and the target of Nazi-like bad guys. Then, we see the Vikaari killing their pursuers using their psychokinetic powers in bloody and cruel ways, apparently without any regret. Needless to say, this completely destroys the narrative tension of the movie and leaves you totally baffled about what the filmmakers wanted to say.

Indeed, I think the filmmakers were badly confused on several planes. First of all, in their decision of presenting this "new race" of children as something that will replace current human beings, engaged in destroying their own planet. Is this a hope or a fear? Difficult to say, but surely evolution doesn't work in that way. 

And then, why the choice of iris-less eyes as a defining mark? Most people rarely consciously perceive the characteristics of the irises of their fellow human beings. But the shape of the iris tells us much of the genetic inheritance of a person -- on this point, the film-makers got it right, although in reverse. A human being without a visible iris is not a modern human.

 

The iris is an easily modified, highly visible human trait. There is a whole genetic story in the human iris. From what we can say, light-colored eyes have been rare, although DNA studies indicate that they did exist in the Mesolithic period. Curiously, Europe is the continent where, nowadays, light-colored eyes are most common. But it is only a few centuries ago that light-colored irises start to appear in paintings. If they had existed before, surely painters would have noted them and shown them in their paintings. Green eyes are a modern trait in Europe, they seem to come from Northern Asia. They do spread easily because they are a typical "epigamic" trait. They give a certain advantage in the sexual competition for mates. 

 

And then, there are limbal rings. The dark ring that surrounds the iris. Also a typical epigamic signal, they are likely to be a feature of the modern main organism of the human holobionts. Here you see the eyes of Sarah Brightman, a modern human specimen, notable for their light green color and well detectable limbal rings. As epigamic signals go, Ms. Brightman is surely beaming them out loud and clear!

 

Note the difference from other mammalian eyes. Most animals, even our close relatives, the apes, have dark eyes, no limbal rings, and not even a large and well detectable sclera. You see it in the image: this (probably) female bonobo doesn't look at all like Sarah Brightman, although she also surely sends powerful epigamic signals to the males of her species. 

So, why do the Vikaari of the movie have no irises and no pupil? They are, actually, the specular version of the "black eyed people," characters of a recent horror movie. In both cases, filmmakers understood that the lack of sclera or of the iris is a characteristic of a creature that is not fully human. A new species (as in Vikaari) or an otherworldly evil creature (as in "black eyed creatures"). No wonder that regular humans react with great perplexity and sometimes violently. And their violence is reciprocated in Vikaari. 

The existence of these films shows our limited understanding, and also limited tolerance, of what makes humans human. A small difference in the extent of the sclera or in the color of the iris is sufficient to turn otherwise fully human creatures into enemies, at least in these fiction pieces. But we all know very well that it happens also in the real world for other, no more important genetic traits, such as skin color. 

 

There is a thin line that separates the horrible from the attractive: nobody would be killed for having green eyes, but the white-eyed Vikaari could be if they existed for real. But that's the way evolution works. Sometimes gradually, sometimes in bumps. The human holobiont of the future will not be the same as it is now and it was in the past. It is the giant holobiont that we call the ecosphere that changes all the time. Onward, fellow holobionts!

Finally, for your curiosity, the "Statue of a Standing Nude Goddess," presently at the Louvre Museum and coming from excavations in the Middle East. Note the eyes without irises. It is not clear if that was a bug or a feature: once they had decided to use rubies for the eyes of this statuette, there was no way they could have shown irises or pupils. But maybe it was intentional: this figure may have been supposed to be somewhat otherworldly or even threatening. Note the horns on her head, a typical attribute of the Moon Goddess. Already at the time when it was made, probably the 2nd century CE, goddesses were rather unpopular and suspicious, not unlike our modern witches.