Infinity in biology. Is life infinite?

Amalia Gabriela Diaconasa

Infinity in biology seems like a contradiction in terms. Because life seems, by its very nature, finite. Since Antiquity, reasonings were built based on the observation, difficult to generalize according to Aristotelian logic, that people are mortal. The empirical observation was that humans are mortal, but can we generalize that every human will die? Not. Although other ancient philosophers, such as the Epicureans, warned of human mortality, which was a source of unhappiness for those close to them, life in general seemed finite to humans, but also to other living things. The exception was the gods. Were the gods a life form? Exactly, the Epicureans believed so. In this big universe, there must be all kinds of life forms. Including the gods as we imagine them. But if those immortal beings with powers that we would consider supernatural exist, then they have no way of caring about us mortals. So we must live our lives the way we want, free from any fear of gods or other supernatural judges.

The ancients considered that immortality, the prerogative of the gods, is something that must be conquered, if we are to follow the Bible. There is a passage in which it is said that "People will learn to live eternally". Mortality was the consequence of the fall into sin. In Eden humans were built to live forever. Death was a punishment for sin. That in the Christian Bible. If we learn to free ourselves from sin, we will live forever. This on Earth. In current human form. And according to Revelation, the resurrection will occur in normal human form after the Last Judgment. Men will return to what they were, in flesh and blood, and live until the end of time. This is a metaphor, because life will be infinite and time will never end.

This is how the ancients saw immortality, although some who lived before the writing of the Old Testament, before Babylon, would not have waited until the Last Judgment. They wanted to never die and live forever. Such was Gilgamesh, son of a goddess, from ancient Sumer. There were several kings with this name in "fortified Uruk". We do not know which of them may have inspired the famous legend. Gilgamesh sought immortality through practical means. After many adventures he found a herb that brought immortality. Only it fell into the sea and was eaten by a fish. So Gilgamesh had to accept his mortal fate. Before that plant, a couple of old men with Methuselahian ages (although their age exceeded that of the famous Biblical character, i.e. Babylonian, the Old Testament being a Babylonian text, according to Noah Yuval Harariri-Sapiens) had indicated to him a set of behaviors that would have brought him immortality. Among other things, he was not supposed to sleep for a long time. Of course, that's when he got the worst sleep, because he did nothing but sleep all day. Then he had to behave in a certain way, including with his wife. Of course, here too, he felt like breaking the rules worse than on normal days. And it's not about the rules of immortality, but also the moral ones (ie domestic violence).

Of course, ancient legends are full of allegories and symbols. They should not be taken as such. What did the old witnesses of the impetuous Flood of Gilgamesh want to tell him? That achieving immortality requires a certain self-control, the observance of some hard rules, which are not within everyone's reach? Indeed, some longitudinal studies, carried out over decades, show that being conscientious is something associated with longevity (Friedman and Martin, 2011). The most conscientious children in the class, good at learning, live longer. Of course, it's about statistics, big numbers. And the impetuous Gilgamesh, a king (not a queen) ready to draw his sword and "kill without judgment at guests" (as did Stephen the Great, later also called the Saint) hardly qualifies for this quality.

What is interesting is that the prohibition of sleep for a long period had been one of the tests for attaining immortality. It's all about self-control, asceticism. But is it about and what does eternal life mean? We do not know the symbols of that ancient culture, written in cuneiform in a language unrelated to any contemporary language. But could it be about "sleeping" some reactions? According to the biochemical hypothesis of aging, precisely the loss of some reactions from the cellular economy and the body could generate what we call aging (Diaconeasa, 2022). Gilgamesh had to not let certain reactions die out, which happens during the development and growth of the organism. It is known that totipotent stem (stem) cells appear only in the early stages of embryonic development in mammals, including humans. Then the stem cells can make, they can differentiate that is, into several types of cells, but not all. During development, not only do stem cells become more and more specialized, that is, they can differentiate into only one (or a few) cell types, but some of them simply cease to exist. And yes, sometimes they do it "with a scandal", i.e. they transform, i.e. they become maligned. This is how some childhood cancers appear. In fact, cancer is an inability of cells (stem) to differentiate. They divide with great vigor, which is lost with age, in fact they can divide ad infinitum, but at the cost of differentiation. That is, they can no longer transform into specialized cells that play their specific role in the body. Of course, with age, normal stem cells lose their ability to differentiate. And here I mean something that really has to do with the environment, that is, the cells of the immune system. With age, at advanced ages, the appearance of specific antibodies becomes more difficult. Stem cells decrease their ability to differentiate.

At least in vitro something even more interesting is happening, at least at first glance. Cultured cells lose their ability to divide after a certain number of divisions. The conclusion that aging would come from the limited ability of cells to divide came quickly enough. The cause of this limited ability to proliferate in cultures was also discovered: an enzyme called telomerase, which is involved in the replication of the ends of chromosomes, on which, normally, an enzyme involved in replication sits, which precisely prevents the replication of these ends called telomeres. The Nobel Prize was also won for this discovery. That's it, we restore the telemerase and that's it, the old age disappears.

But things are more complicated. A critical discussion of telomerase, the replicative limit of cells in cultures (Hayflick's limit) is here (Diaconeasa, 2022). In short, telomeres are also synthesized in the absence of telomerase by other mechanisms (in malignant cells that divide indefinitely) and telomerase is not absent in all types of adult cells. And anyway, it would be wonderful if humans lived long enough for their cells to divide a number of times equal to the replicative limit for cultured cells of our species.

Without continuing the discussion on the slope of aging, we can mention that life depends on biochemical reactions and reactions, and aging is only a phenomenon that occurs in some species. About some we do not know if they grow old, and anyway the life of others, who grow old, can be very long. So animal life, of mammals, is limited and fragile.

Is life infinite?

Can we talk about infinity in biology when life seems so fragile? Yes, we can really talk. It depends on how we define life and where we see fragility. What is lost is a certain type of information. Ability to differentiate or proliferate. In fact, senescent cells, those that no longer divide in cultures, would be highly differentiated. They have specific functions in the body anyway, such as wound healing (although things are not as iin vitro). It is largely the ability to differentiate that is lost with age, in aging, but also in development. Totipotent stem cells, which can differentiate into anything, are also in mammals only in the first stages of development.
But is life the ability to differentiate into whatever we want? It would be nice if those totipotent stem cells could also differentiate into cells of therapsid reptiles (our mammalian ancestors) or other distant species in the mammalian and human phylogeny. Let's not forget, malignant cells are immortal. HeLa cells have been replicated for decades in laboratories around the world and are still dividing. The freshwater hydra, consisting almost entirely of stem cells, appears to be immortal. But the most interesting thing: bacteria are immortal. They have been on this planet for a billion years and are still holding on. I mean they're still splitting up. And their ability to acquire new characters is amazing. In a short time, they can acquire incredible characters such as resistance to antibiotics or the ability to metabolize new substances they have never encountered before. Of course, they also lose these characters (information) if they no longer meet her. If we stop taking antibiotics, the bacteria lose their resistance. But they have been constantly dividing and replicating their genetic material for billions of years (life on Earth is apparently over 3 billion years old). And since then they adapt in their own way. It can be said that life is, if certain conditions are maintained, infinite.

But what is infinite in life? In an attempt to explain altruism in biology, considering that natural selection, the struggle for existence, would involve a continuous war with the whole world, what Hobbes called "the war of each against all" (bellum omnium contra omnes), Richard Dawkins appeals in "The Selfish Gene" to the "selfishness" of genes that would lead to altruistic behaviors in the sense of gene survival. That is, the gene urges you to altruism out of its own selfishness, the gene's, in order to survive, through alliance with other genes and complicated strategies. The gene is immortal, it is the infinite, immortal entity in biology, according to Dawkins and his followers. Genes manipulate us in their own, super-egoistic interest.

Yes, I don't know what Dawkins' countryman would have said. William of Occam, of this reasoning. We're only talking about complexity, why would the razor work, not accuracy. Especially since selfishness, starting with bacteria and continuing with everything Kroptkin describes in "Mutual Aid: A Factor of Evolution", who did not know about bacteria, is contradicted by the facts. Bacteria, the ones that survive for billions of years, throw into the environment plastids (pieces of genetic material) with antibiotic resistance genes and the ability to metabolize the strangest substrates after they have managed to acquire them through their own mutations. In other words they share their discoveries with all their neighbors, relatives, even friends of other species. Kropotkin shows that selfishness and the struggle for existence, although they exist, are overshadowed by cooperation. And the human species, although capable of killing congeners, is capable of cooperation, and cooperation is an important factor of human evolution, of humanization.

Cooperation and precisely generosity is a characteristic of life in its primordial form. Should aggression and its manifested form, violence, actually be forms of differentiation, characters, like the eye or the foot? But life does not have to have eyes or feet, although evolution has developed them many times independently in evolution.

What Dawkins describes with his selfish genes is more viral behavior. Viruses are genes with a few proteins encoded by these genes, but no metabolic machinery. It can be said that they colonize the host's cells and put their metabolic, protein synthesis apparatus into action, diverting them from their proper functions. That is, the cell, instead of synthesizing its own proteins, synthesizes those of the virus. But can you say such a thing? The virus is like a foreign substance that is not subject to cellular regulation. You can say it's an intracellular parasite, but the parasite is alive. The virus is not alive. It is a more complex molecule with the ability to enter the cell and interact with cellular material. Hormones also enter the cell (some), causing reactions, even if they are not produced by that organism. Can we say hormones are selfish? Hormones, like viruses, genes, do not represent infinity in biology. Especially since, as we have seen (not with pleasure), the "selfishness" of viruses, especially RNA, does not go very far. Their genetic material undergoes numerous mutations, which confuses us when producing vaccines. DNA is more stable, it is believed that this is why it evolved as genetic material. The first "informational" molecule of nucleic material type would have been RNA.

What would be the infinite part in biology? Life itself, what defines it. If the environment does not change in such a way as to destroy life forms, it continues indefinitely. We can say that it is a perpetuum mobile. Not of type I, which is not possible anyway, according to the first principle of thermodynamics. Life develops and evolves following the 2nd law of thermodynamics. Flowers bloom, embryos develop due to this principle.

Life continues for a billion years without pause, often taking exotic forms, such as ammonites, dinosaurs, mammals, which anyway were/are only carriers of bacteria, possibly plants. Because, contrary to what the ancients saw, animals are at the service of plants and especially bacteria, and not the other way around. There are more bacterial cells in the human body than human cells. Moreover, eukaryotic cells, with a well-defined nucleus and other cellular compartments where specific reactions take place, originate, according to Lynn Margulis' hypothesis, from an endosymbiosis, i.e. a cellular symbiosis between bacterial cells. Mitochondria of animals and plastids of plants, where reactions of cellular energy production through oxidation and photosynthesis take place, were originally bacteria. Although some of the mitochondrial genes are encoded by nuclear DNA, they divide like bacteria and are transmitted like bacteria through the cytosol of the egg from generation to generation.

And then what is life? Life takes place in the cytosol. Proteins with various functions are synthesized there, cellular biochemical reactions take place there. In the bacterial cell, which is not compartmentalized, there also takes place the replication of the genetic material, the bacterial chromosome. Life is metabolism, but can it be reduced to that? Is a tank where biochemical reactions take place life? Not. Because life is something that sustains itself. That is, it supports its own thermodynamic imbalance. The imbalance is self-perpetuating through gradients, including the membrane. Life probably began with the membrane, with the separation of a reaction medium in a lipid droplet. But that was not enough. Life produces its own energy. That it comes from redox reactions, from photosynthesis (in blue-green algae, which are prokaryotes, they do not have a well-defined nucleus, just like bacteria), which after all is also a redox reaction (the oxidation of a magnesium atom), life produces its energy by which it supports some of its reactions, including those that ensure its thermodynamic imbalance. The electrical polarization of the cell membrane is energetically maintained by ion pumps, which consume ATP (a molecule that packs a lot of energy into its bonds) to function. Probably first molecules like nitrogenous bases were used for the purpose of energy storage, then their role of encoding information appeared. Life takes place in the cytosol. It can continue without the core, but at a reduced speed and with the loss of division capability, as well as other functions. In mammals, erythrocytes do not have a nucleus, but carry out the function of transporting hemoglobin. Of course, they depend on the whole organism. We can assume that in the beginning, the genetic material appeared in some entities, then it spread by donation, as it happens now in bacteria?

Life is infinite because living organisms are small factories of thermodynamic imbalance. Life is such a factory, because cells, however simple and however complex, communicate with each other. Put in difficult conditions it makes inventions, such as those given by the mutations of bacteria. But sometimes complicated structures are involved in these inventions. Life can produce structures responsible for walking, seeing, hearing, many strange behaviors, necessarily some related to reproduction, but whatever it is it produces its own membranes (if not cell walls as in bacteria and plants), its own energy and imbalances in the environment. We have reason to believe that it is infinite, if it has been going on for over 3 billion years. Everything we see began with the first reactions in living cells. We are the consequence of 3 billion years of reactions. The apocalypse, if there is one, i.e. following a very destructive cataclysm, will maintain life forms with essential characteristics, i.e. bacteria. Life will survive as life until it is no longer possible.

Bibliography

Dawkins, R. The Selfish Gene, Oxford University Press, 2007

Diaconeasa, A. G. Missing Links in Aging, Ninsun, 2022

Friedman, H.S., Marlin, L.R. The Longevity Project: Surprising Discoveries for Health and Long Life from the Landmark Eight-Decade S tudy, Hudson Street Press, 2011

Harari, Y. N., Sapiens: A Brief History of Humankind, Vintage, 2015

Kropotkin, Peter, Mutual Aid: A Factor of Evolution, Dover Publication Inc, 2006