Monday, March 30, 2020

The March of the Holobionts: Why Gaia is one of us

As a Goddess, Gaia may not be all-powerful, but She does what She can.

One of the good things about the current epidemic is what it is teaching us. Apart from a welcome slap to human hubris, it is a test of population models (right now, it seems that everyone I know is busy at fitting data with logistic equations). But there is more than population dynamics in this story. It is the occasion for a reflection of the role of viruses in the ecosystem. In my case, it led me to discover concepts that I only vaguely knew before. One is that of "virome," a term analogous to that of "genome" -- the idea that viruses are part of us. Did you know that 8% of the human genetic code is directly derived by viral genes? The role of viruses in our metabolism is still largely to be discovered, but surely most viruses are not pathogens, they are commensals or symbionts. Companions of our travel to an unknown destination.

And then there is the related concept of "holobiont" -- a term originally invented by Lynn Margulis, the co-discoverer, with James Lovelock, of the idea of "Gaia" as a homeostatic planetary system. Once you learn what a holobiont is, your view of the world changes completely. The evolutionary unit of the ecosystem is not the organism, but the holobiont: an ensemble of creatures that cooperate with each other without sharing the same genetic code as multicellular organisms do: a tree is an organism, a forest is a holobiont. The forest holobiont includes not just trees, but all the animals together with the microbiome of fungi, bacteria, archaea, viruses, and everything.

That opens up a whole new evolutionary frontier: multicellular organisms transmit genetic information by the complex process of sexual reproduction followed by competitive selection. Holobionts do something similar, but they don't have a genome that they pass to their descendants by sexual transmission, they have a hologenome that successful holobionts can transmit using different strategies. And that answers a difficult question: who is Gaia, exactly? You guessed it, the Queen of Heaven and Earth is a holobiont! As a Goddess, She may not be benevolent and merciful, surely not all-powerful, but she does what she can. She is one of us.

Below, a translation of an article that I submitted to an Italian newspaper, "Il Fatto Quotidiano" where I try to explain some of these concepts. These submissions are limited to ca. 650 words, so you have to be extremely synthetic and also take into account that the readers are ordinary people, not scientists. So, I didn't mention the concept of holobiont, maybe in a future article. But I thought that also the readers of "Cassandra's Legacy" will find it interesting in this short text. (BTW, as a translation service, Yandex seems to be somewhat better than Google).

Coronavirus: what's happening?
Submitted to "Il Fatto Quotidiano" by Ugo Bardi

Translated using Yandex, slightly revised and modified

The most recent data indicate a decrease in the number of coronavirus infections in Italy. That means we could get out of the epidemic in the coming months. But why do we expect this trend? It is explained in the field of Science called "epidemiology" that studies how epidemics spread.

The first epidemiology studies date back to 1927, when two British researchers, Kermack and McKendrick, developed the "SIR" model (susceptible, infected, removed), still used today. However, the basis of these studies was the previous work of the American Alfred Lotka and the Italian Vito Volterra. A few years earlier, they had developed the model that we now call “Lotka-Volterra,” but also “predator-prey,” or “foxes and rabbits” (although neither Lotka nor Volterra ever spoke of foxes or rabbits).

Let's explain. Imagine a green islet in the middle of the sea, populated by only two species: foxes and rabbits (there is no such island, but let's take it as a hypothetical example). The population of foxes (predators) tends to grow when rabbits (prey) are abundant. It grows so fast that, at some point, the surviving rabbits can no longer reproduce quickly enough to replace those eaten by the foxes. The rabbit population reaches a maximum and then falls. At this point, Foxes starve. With few foxes around, the remaining rabbits can reproduce peacefully and the cycle begins again.

The model is based on the idea that predators tend to take more resources than nature can replace: it is what we now call "overexploitation” It always ends badly, but the model describes the trajectory of the populations that first grow and then collapse as a bell-shaped curve. An example of a real case is that of St. Matthew Island in the Pacific. There were no reindeer on the island before the US Navy brought some, in 1944. In a couple of decades they became thousands, they devoured all the grass, and then almost all died of starvation. Then, a couple of particularly harsh winters exterminated the last individuals, sick and hungry. Reindeer was the predators and grass the prey: a classic case of resource overexploitation.

Not that the model can explain the complex interactions in a whole ecosystem, but it is useful to provide us with a framework for what's happening. And we can use it to understand the current epidemic. It is the same thing: the virus is the predator and the prey is us. The population of the virus is growing rapidly as it always happens when resources are abundant. But soon the virus will begin to run out of prey, fortunately not because infected people die (some, unfortunately, do). They are no longer prey because they become immune. Indeed, the epidemic is following the bell-shaped trajectory predicted by the Lotka-Volterra model.

So, nothing unexpected. Viruses are creatures looking for resources just like we do. They're doing nothing different than what we did in the past by exterminating species like mammoths or the dodo. And, today, with the huge expansion of the human population over the last 1000-2000 years, we have become a great hunting ground for so many micro-organisms, also because of our tendency to live in crowded cities where it is easier to get infected. Thus, the past history is full of epidemics: plague, smallpox, cholera, influenza and many others.

In a way, we are at war: viruses attack us and we defend ourselves with vaccines, antibiotics, hygiene, and our immune system. But, if it's a war, we won't necessarily win it. Maybe we'll find a vaccine for the Sars-VOC-2 virus, but don't expect miracles.

Actually, species do not make wars against each other: they adapt, that's how the ecosystem works. Viruses and bacteria are seen almost only causes for diseases, but our body hosts a large number of them and of many different species. They are not parasites, many are "symbionts" – creatures that help us with so many things, think of our intestinal bacterial flora. So, in time, we'll end up adapting. And the virus will adapt, too.


A comment from Ugo Bardi's personal troll: Mr. Kunning-Druger

Mr. Bardi, you are just beating the bush, as you and your warmunist friends usually do to confuse the public. Now you mix magniloquent words at random, goddesses, viromes, holothis and holothat. And what does that mean? That we should welcome being infected by a virus and die? You are being exposed once more for what you are: an enemy of mankind.  So, if it has been all a fault of those stupid pangolins and bats (and those disgusting Chinese who eat them), well, there is a simple solution. As you said, our ancestors exterminated stupid animals like those dodos, why not exterminate pangolins and bats, which must be just as stupid? Problem solved. The reality is that man has no obligation toward nature, except to put it back in its proper place when needed. Now, it is the time to shelve those silly plans such as the energy transition and the green new deal. We need to go back to growth, and do that fast.


Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)