Origin of life

The origin of life

Time and the increased complexity of life

The complexity of the processes that take place within the cell is amazing, and challenges the human mind. This complexity has not always existed, but developed through an evolutionary process that went from time X, in which there was no cell on our planet, to time Y, in which the first unicellular organisms were already present. The chapters of the story that led to the development of our organism and brain have been written on Earth since nearly four billion years ago. This story is all recorded in the body of each of us, not as a memory accessible to our consciousness, but as a series of informatics instructions, indispensable in their complexity to develop and maintain the organization of the human body, the living instrument through which consciousness can experience the psyche's events. Due to the limits of our perceptive faculties and the lack of integration in our consciousness of all the unconscious functions of our brain, our body may even appear to us as an alien entity, and for centuries humans have argued of body and soul, without knowing anything reliable about either the one or the other. Thanks to science, today we know at least something about our organism, and what we know lets us open-mouthed in wonder.

Information: the fundamental factor in life's development

The organism's complexity concerns humans as well as animals and plants. There is no difference, in this regard, between a man, a cat or a tree. There are some features that distinguish humans from animals, but for now, starting from the cellular level, let's observe how an essential component, information, is transmitted and incorporated into living organisms. For example, at the level of some millionths of a millimeter we find small molecules composed of few dozen atoms (the hormones) that circulate easily in our body and carry chemical messages, that is information. But what does information, that constitutes the very essence of life (from the simplest to the most complex forms), consist of? It is a resource, which we can define creative, by which a physical state becomes a different and more complex physical state according to a codified rule. It has two fundamental aspects: the first, related to the development and execution of instructions, is represented by that series of rules through which, with the variation of environmental conditions, a system moves from one state to another. Said in these terms it seems to be something complicated, but we can explain it with a very simple example. In our cities there are street lamps that turn on when ambient light intensity falls below a certain value and off when the light intensity exceeds that value again, then usually turn on at dusk and off at dawn. They are connected to a simple servomechanism equipped with a sensor, a power supply and a switch that opens and closes the electric circuit connected to the lamps. The information given by light intensity, that is, by ambient conditions, determines the state of the system: switch on or off. Note that in this example the operation of the servomechanism is entirely automatic, however the instrument was conceived by an external intelligence that designed it in relation to the environmental conditions, the required performance, and the purpose for which it was programmed.

The other aspect concerns the encoding and transmission of information, which is represented, stored and transmitted by changes in the state of the physical support. Although not constituted by the physical support, information is affected by the physical limits of it, and is also correctly transmitted only if the transmitter and the receiver share the same code. If a person speaks, the information contained in his words is transmitted through the propagation of the sound waves in the air, or by a microphone, through the electric current modulation, the amplifiers and the speakers: these physical devices do not constitute the information, which is coded in the words said by the speaker. The listener can decode the information only if he shares with the speaker the code of the spoken language: for example, if the listened word were burro, the decoding of an Italian would remind him of that milk-based substance used to flavor some food (butter), while a Spaniard would think of a donkey. Therefore, information is an extra-physical entity, not interpretable in terms of mass-energy, but still subject to the laws of physics as it is contained and transferred through a physical support: it can be created and destroyed, and requires energy to be transmitted or used.

Let us now see how to interpret, in the light of these notes on information, the transformations that have led to the appearance of the first living organisms on our planet. Utilizing as little as possible the very imprecise term of matter, what exists in the physical world are substances present in a certain state (solid, liquid, gas). These substances are formed by molecules, in turn formed by linked atoms, and the atoms are made of energy organized according to certain rules. A living organism is not the result of accidental mixing of the substances that compose it. The fact that our body consists of a number of pounds of hydrogen, oxygen, carbon, nitrogen, calcium, with a handful of phosphorus, potassium and magnesium and a minimum dose of iron, iodine and other elements, does not mean that the right doses of all these substances are enough to make an organism: it is also required a huge amount of information that has been elaborated and inserted into living organisms during those four billion years of evolution that I have mentioned. If we compare the atoms to the letters of an alphabet, and the molecules of the substances we are composed of to words formed with those letters, it is possible to have an idea of the meaning of the whole story only through the information contained in all the paragraphs of the story, starting from its beginning. What would show us the frame of a film is an evolution in which each frame highlights the existence of more complex systems than those in the previous frames: that is, systems involving a greater amount of information inserted and operating inside them.

Hypotheses on the origin of life

The idea that science gives us about how this process has begun is roughly the following: in a certain environment, at some time energy conditions made so that some substances, made up of simple molecules, joined together to form more complex molecules. Each of these new molecules, which did not exist before and begun to exist since then, represented a new substance, a new word in our history, and thus a system containing new elements of information. But as a whole, these new substances contributed to an environmental change that allowed the information to advance a new step: so much more complex molecules were produced, containing all the information of the previous levels, which further modified the environment. An example of this process is given by the appearance of oxygen in the Earth's atmosphere. Today neither humans nor most animals can live without oxygen, but up to about two billion years ago the presence of this element in the atmosphere was minimal. Cyanophytic unicellular algae, present in huge quantities in the planet's waters, produced oxygen as a residual substance of chlorophyll function, and since then oxygen was used in animal evolution for energy production.

We have seen that information transmission is determined by environmental conditions, and that the information is transferred to an organized system immersed in those environmental conditions. This is true for the simplest precursors of unicellular organisms as well as for our body, which is a protected system surrounded by an environment with which it continuously interacts: it is evident that the body's life depends on environmental conditions. The transmission of information in the physical world required time and energy: it took more than one billion years to develop the first prokaryotic unicellular organisms, while nucleated cells made their appearance about 1,400 million years ago and multicellular organisms around 600 million years ago. The information in the system determines a potential for development, but environmental conditions, which still have a variable and random character, can support or block such development, or limit some aspects of it. For example, even if the seed of a plant contains all the information necessary for the plant's developmen, a seed transported by the wind may either end up in a place where environmental conditions (humidity, temperature, soil) help its germination (even if a bird can always come and eat it or an ant can take it away), or in another place where germination cannot happen. If we then consider the seed as an individual, that is, a closed system, we see that even if the information that determines its development is embodied within it, in part it depends on the external conditions in which the seed happens to be. And this also applies to the whole subsequent plant's development.

Organisms as information systems: the source of information

The progressive complexity of living organisms, considered as systems in which an increasing amount of information is embedded, leads us to ask whence this information originates. It does not matter the name we want to give to this process, that is, the label glued on the jar: we are interested in knowing the jar's content. As label we can use the word creation, or nature, or evolution, or case, depending on everyone's tastes, but what we are interested in understanding through the way in which information was transferred into the physical world, determining the evolution of life on our planet up to the level of human beings, is the source of information. The main processes that characterize a cell are: the presence of a closed boundary (membrane), which separates the cell's interior from the environment; the exchange of substances between the internal organization and the environment and the resulting growth of the cell; the ability to reproduce, and then multiply, once reached certain dimensions. The level of organization of the cell and its membrane is significantly higher than that of the outer environment: this latter, however, must have the proper requirements for the cell to survive, otherwise the cell would meet its destruction. These requirements essentially consist of the presence of certain substances and the availability of energy within a range compatible with the needs of the cell.

It is evident that the processes that occur within a cell are carried out in a way that we can define intelligent, in the sense of programmed. Even the most automated industrial factories, designed by human intelligence, have a lower level of complexity compared to the processes that occur in a single cell. Human intelligence is able to conceive and design automatic systems similar, within certain limits, to those operating in the cell, but these systems exist and operate, even autonomously, only because they are designed and realized by humans. A cell's operating systems are certainly not designed and realized by human intelligence, so there are two possibilities: either between time X, in which a particular system did not exist, and time Y, in which that system had become fully operative, there was a form of intelligence, outside the physical dimension, endowed with the power to progressively transfer information within the physical system; or all the information was already present in the universe, in a potential state, from the very first moments of its existence (the so-called big bang). This potential, existing out of time, would be transferred into the physical world with the passing of time: between time X and time Y, an evolutionary process was carried out whose potentials were already implicit in all the elements and factors present in time X, but for whose implementation it was necessary the presence of conditions different from those existing at time X.

Information as a creative essence and as the basis for intelligence

In both cases information is the quintessence of creativity, the indispensable premise for the existence of what did not exist before. Indeed, the second hypothesis too implies a constant increase in order and information within closed and defined systems, and therefore requires a wider understanding, and perhaps a redefinition, of the concept of intelligence. In fact, even in the case of automation systems produced by human intelligence, we can always locate a time X in which there is no trace of such systems, and a time Y (following X) in which such systems have been realized. At time X, it was not possible to conceive or design such systems, not because of a lack of intelligence, but because of the lack of resources or knowledge required for their realization. This is the reason why, for example, computers – so widespread in our days – could not be realized a century ago. On the other hand, the origin of the same human intelligence remains a mystery to us, since none of the animal species other than man shows, even at a reduced level, the skill to understand, conceive, design and build, that we can find within our species, where however only some of the social organizations and cultures have developed the intellectual faculties at a level adequate to the design and realization of technologically advanced products. And even in these socio-cultural systems, not all the individual intelligences are at the same level, but relatively few are able to conceive, design, organize and manage complex systems, while most people act as support workers, and some even show hostility to the system itself.

Vital intelligence and human intelligence

At a basic level, in the organic sphere, a cell can operate, grow and reproduce equally well, whether it is part of the organism of a worm, a horse, a human being belonging to a primitive culture or a scientist with in-depth knowledge of cellular biology. As for the origin of the complex internal organization of the first cells, this is a process that developed over hundreds of millions of years: an incomparably long time when confronted with those required by the processes of ideation, design and realization by human intelligence. It seems obvious that a very close relationship between the variations in time of Earth's environmental conditions and the implementation of the processes that led to the development of life should be assumed, since the same billions of years have passed on other planets without any evolutionary process, similar to what led to the emergence of life in our world, occurring on them. For this reason Earth, within the solar system, can rightly be defined as a living planet.

However, we must keep in mind that in developing an interpretive scheme of what happened on Earth in the oldest geological eras, we can not always rely on certain and objectively verifiable data, but we must also refer to hypotheses that could have a high degree of reliability. Sometimes there is a wide gap between what actually exists now (the cellular structure with all the processes that occur in it) and the hypotheses suggested to explain the evolution of the processes that led to the formation of protocellules starting from the first organic molecules. Virchow's assertion, made in the nineteenth century, that «every cell originates from another cell», obviously cannot be infinitely backdated, and it is assumed that there has been a period of time, more or less long, in which several components of the present cellular structure interacted with each other without the existence of true cells.

We are not in a position to follow the process in its progressive development from the beginning, but we have to rebuild the path that has led to the present complexity starting from initial conditions which were such that, if hypothetically a conscious but unaware observer present at that time had been able to perceive them as a whole, not even with the most wild fantasy he could have imagined a development like the one that then occurred. The original environment of the Earth, at the dawn of its history, did not have anything in it that would foretell such an astonishing future: who could predict that from the progressive cooling of that chaotic and magmatic world could emerge a land surrounded by seas and swarming with living organisms? It is true that between these two scenarios a period of billions of years passed, but in the same span of time, as I said, on other planets nothing like that happened. Given that evolution is not a foregone conclusion in a planet's history, some scientists think that in the case of the Earth certain particular environmental circumstances occurred, which could not help but give rise to all the series of subsequent events. This conception considers the development of life on Earth as the necessary and automatic consequence of the original situation, represented by the size and composition of the Earth, the presence and composition of the atmosphere, the size and distance of the Sun, the motion of the Earth around the Sun, and so on.

So, as I have already noted, we must necessarily assume one of the following two hypotheses to explain the process that has led to the appearance of organic life: either the intervention, at least occasional, of external entities gifted with a form of intelligent energy that was transferred to the Earth system, determining an increase in organization and information in it; or, alternatively, the attribution of a form of intelligence to the process itself. In fact, if we attribute a certain level of intelligence to humans and then we want to derive our origin solely from the evolutionary process, we must attribute to the process itself all the qualities we have and also those that will emerge in the future through the progress of evolution.