Epigenetics, complex systems, etc

Strange, the functioning of the human spirit: hardly one discovers something which one believes all to be able to bring back to this new discovery. Hence endless debates, decades of wasted ink and saliva, wounded self-love, instead of simply profiting from the discovery and calmly seeing its limits.

At the beginning of the last century, the discovery of conditioning opened the way to behaviorism: we meant to explain everything with acquired reflexes, in the almost total negation of instincts or innate potentialities. Then came the discovery of DNA in the middle of the century: this time, it was the innate who was supposed to explain everything by the action of genes transmitted hereditarily.

More recently, it was found that gene expression was modulated by environmental factors. The discoveries in the field of complex systems demonstrated that everything is not predictable as implied by classical physics, and that certain phenomena or certain properties can emerge under the effect of imponderable factors as soon as a system exceeds a certain level of complexity. We can predict the trajectory of a particle when we know its characteristics (in particular its speed and direction), but we can no longer predict anything when a system includes myriads of particles, i.e. disorganization processes (chaos ), or a process of self-organization is set up under the effect of interactions with the environment.

Suddenly, some minds embark on a negation of genetics: a living organism is a highly complex system, so it can be the seat of phenomena of chaos or of emerging processes, genes are not everything, therefore genetics do not. ’explains nothing and it must be abandoned. The laws of evolution, based on the transmission of genes, therefore no longer have the right of citizenship, nor the notions of hereditary instinct. So here we are again at the behaviorism stage: it is the environment that does everything.

All of these extreme views are obviously ridiculous. Just because genes don’t do everything doesn’t mean genes won’t do anything. The innate and the acquired are inseparable, as Konrad Lorenz observed, for example, a long time ago. But is it a mistake to speak of innate and to speak of acquired?

The error would consist in wanting to explain everything by the acquired or in wanting to explain everything by the innate. But resorting to these concepts makes it possible to approach the problems on an analytical basis and to build models of explanation. Any model is of course limited, but it can still be of service.

We are constantly faced with this kind of dichotomy when it comes to biology or psychology. For example, instinctotherapy uses the notion of dietary instinct, including alliesthesia mechanisms and other body signals related to food. This food instinct is considered to be innate, therefore as genetically programmed. In fact, exactly the same mechanisms of flavor change are observed in all individuals of the species (except in rare cases of anosmia). There are therefore good reasons to believe that these mechanisms are transmitted innately.

But this does not exclude the influence of the environment. It is clear that the first contacts with the food environment can determine different modes of operation, or a different psychological recognition, of the same mechanisms. It is even there one of the essential parts of the instincto, to find the functioning of the dietary instinct as it would be put in place in a natural environment (without artifices modifying the flavors of food given by nature), then to use the signals of the body (attractions, rejections, dislikes, etc.) in order to better regulate the nutritional balance.

To deprive oneself of notions of innate and acquired knowledge would open the way to any speculation: emerging properties can arise from the complex self-organized system that we are. So we can adapt to anything. Even if we have nothing more than stones to eat, a new property of our digestive tract will emerge and allow us to survive. The example is trivial, but shows that there are certain limits which it is not possible to exceed.

Likewise, it is not because genes do not determine everything that we cannot reason in terms of genetic adaptation. An organism is certainly endowed with a certain capacity for adaptation, greater than suggested by strict genetics when it strove to reduce everything to a simple series of genes, each supposed to determine a precise function. The mechanisms regulating the expression of existing genes (or epigenetics) allow it to face situations very far from the situation which may have governed the evolution of the species. Emerging properties have also possibly to evolve the species much faster than the classical processes of mutation-selection.

Whatever the adaptive capacities of a species or an individual, the basic question of instinct remains perfectly valid: does our daily food correspond to the genetic data of our organism? The notion of genetics as it should be understood here includes everything that revolves around genetics, in particular epigenetics and the surprises that can be held by complex self-organized systems.

Simple common sense would avoid all these theoretical digressions: any system in interaction with the environment, whatever this system, has a margin of adaptability to possible changes in this environment. But this margin of adaptability is limited, and the question remains to know to what extent the system will be able to adapt to a given change, or whether it will be subject to processes of disorganization, or even chaos, if this change exceeds its margin of adaptability.

It is very clear when it comes to food: everyday food has seen its characteristics change profoundly in a few thousand years. It is therefore a question of whether these changes remain within the limits of adaptability of the human organism, or if they cause certain functional disorders inherent in human pathology.

In other words, the discoveries in matters of epigenetics and complex systems change absolutely nothing in theory or in instincto practice. The only valid conclusions are those that can be drawn from empirical research on organisms located in their environment, due to the complexity and unpredictability of the factors involved. Without excluding, however, the data provided by analytical research that invalidates or confirms the initial hypotheses or the practical rules drawn from observation.