Why your biology depends on the senses

Do you think feelings are important? You have no idea how right you are.

I have long been interested in such a property of a person as an affect - the world of its emotions and feelings - and I have studied it for many years: why and how we have emotions and feelings, how we use feelings to create ourselves; how feelings help undermine our best intentions; how and why the brain interacts with the body and supports such functions.

The idea itself is extremely simple: the merits of feelings, like motivation, observers, mediators in human cultural affairs, are not recognized enough. People separated themselves from other creatures, creating stunning collections of objects, practices and ideas, known under the generic name "culture." This collection includes the arts, philosophical issues, moral systems and religious beliefs, justice, government, economic institutions, technology and science. Why and how did this process start?

Often, answering this question, affect the important ability of human consciousness - language - and such distinctive features as intense sociability and superior intelligence. For people prone to biological explanations, natural genetic selection is also included in response. I have no doubt that intelligence, sociability and language have played key roles in this process, not to mention the fact that people's abilities for cultural inventions have developed in man through natural selection and transfer of genes. But the idea is that it took something else to launch the saga of human culture. And it was a motive. And speaking of the motive, I mean feelings.
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Does the fish have feelings? “After the nervous system entered the stage, the path for the senses opened up,” writes Antonio Damasio. “So even modest nervous systems probably have feelings of some kind.”

To understand the origins and the emergence of functions, as well as to pay tribute to their contribution to the human mind, it is necessary to place them on the panorama of homeostasis . The traditional concept of homeostasis speaks of the possibility inherent in all living organisms to constantly and automatically support the work of their functions, both chemical and physiological, within values ​​compatible with survival. But for many sentient beings, and certainly for humans, such a narrow use of the concept of “homeostasis” does not correspond to reality.

Of course, people still use and benefit from automatic control systems: the level of glucose in the blood can be automatically adjusted to the optimal gap through complex operations that do not require the conscious intervention of the individual. For example, the production of insulin by pancreatic cells affects glucose levels. However, humans and many other species with a complex nervous system have an auxiliary mechanism in which mental sensations participate, expressing a certain value. The key to this mechanism is feelings.

What is important, feelings are not independent works of the brain. It is the result of the cooperative interaction of the brain and body, communicating with the help of free chemical molecules and nerve paths.

The correspondence of pleasant and unpleasant sensations with positive and negative ranges of homeostasis is a confirmed fact. Homeostasis in good and optimal ranges is expressed in the form of well-being and even joy, and the happiness caused by love and friendship improves the efficiency of homeostasis and has a positive effect on health. Negative examples are just as obvious. Stress associated with sadness is caused by the work of the hypothalamus and pituitary , emitting molecules that reduce homeostasis and damage countless parts of the body, such as blood vessels and muscle structures. Interestingly, the homeostatic burden of a physical disease can activate the same axis of the hypothalamus-pituitary, and cause the production of dinorphins , molecules that cause depressed mood.

The vicious circle of these operations is remarkable in itself. At first glance, the mind and the brain affect the body as much as the body affects the brain and mind. These are just two aspects of the same being.

Whether the senses correspond to a positive or negative range of homeostasis, various chemical signaling systems and their corresponding internal states can change the flow of thoughts, both implicitly and explicitly. Attention, learning, memory, imagination - all this can be damaged, and the approach to tasks and situations, both trivial and difficult, can be broken. It is often difficult to ignore the mental disorder caused by emotions, especially negative ones, but even the positive feeling of a peaceful, harmonious existence cannot be ignored.

The roots of the correspondence between life processes and the quality of sensations can be traced to the work of homeostasis in common ancestors in the endocrine, immune and nervous systems. They stretch to the mists of early life. The part of the nervous system that is responsible for studying the environment and reacting to internal sensations has always worked in conjunction with the immune and endocrine systems.

When the body receives damage due to, say, a disease that has come from inside, or because of an external cut, there is usually a sensation of pain. In the first case, the pain arises due to the signals transmitted by the old system, bezkotnymi nerve fibers of group C , not having a myelin sheath, and the localization of this sensation can be vague; in the second case, myelinated nerve fibers, evolutionary later, are used, capable of transmitting clear and well-localized information about pain.

However, the feeling of pain, vague or clear, is only a part of what is happening in the body, and from the point of view of evolution, a rather new part. What happens besides this? What is the hidden part of the process?

The immune and nervous response is caused by wounding locally. These reviews include inflammatory changes, which include dilation of blood vessels and the flow of leukocytes (white blood cells) towards this area. Leukocytes are called upon to help fight or prevent infection and remove debris from damaged tissue. The last they carry out through phagocytosis - the environment, absorption and destruction of pathogens - and the first through the release of certain molecules. An evolutionarily old molecule — proenkephalin , a hereditary molecule, the first molecule of its kind — is capable of splitting into two active components working locally.

One of the components is an antibacterial agent; the other is an analgesic opiate acting on a special class of opioid receptors , the delta class (δ), located in the peripheral nerve endings. Signs of local damage and reconfiguration of the state of the flesh become available to the local nervous system and are gradually laid out, contributing to a multi-layered feeling of pain. But at the same time, the local release of opioid molecules helps alleviate pain and reduce inflammation. Thanks to this cooperation of the nervous and immune systems, homeostasis works, protecting us from infection and trying to reduce inconvenience.

But the story does not end there. The wound causes an emotional response, which in turn causes its own set of reactions; for example, muscle contraction, which can be described as a shudder. Such reactions and the guarantee of changes in the configuration of the organism are also noted, forming a definite view of what is happening in the nervous system. Creating an understanding of motor reactions helps to ensure that the situation does not go unnoticed. Interestingly, such motor reactions appeared in the process of evolution long before the nervous systems. The simplest organisms bounce off, shrink and fight in the event of a violation of the integrity of their bodies.

In general, the set of reactions to injury, described by me on the example of a person - antibacterial and analgesic chemicals, startle, actions for evasion - an ancient and well-structured reaction, resulting from the interaction of the body and the nervous system. Later in the evolution, when organisms with a nervous system learned to mark events not related to the work of the nervous system, they learned how to create ideas about the components of this complex response. The mental sensation, which we call the “pain sensation,” is based on this multidimensional picture.

The bottom line is that the sensation of pain is fully supported by a whole set of old biological phenomena whose goals are obviously useful in terms of homeostasis. To say that the simplest forms of life, which do not have a nervous system, have a feeling of pain, is unnecessary and incorrect. They definitely have the elements necessary to build a sense of pain, but it is reasonable to assume that for the appearance of pain as a mental sensation, the body needs to have a mind, and for this it needs a nervous system capable of marking out structures and events. I suspect that life forms without nervous systems or minds have complex emotional processing systems, protective and adaptive action programs, but not feelings. After the appearance of the nervous systems, the path to the senses was opened. Therefore, even modest nervous systems probably have feelings of some kind.

It is often asked, and quite reasonably, why at all we should feel some kind of feeling, pleasant or unpleasant, fairly quiet or unbearable. Now it should be clear: when the whole constellation of physiological events that make up feelings began to appear during evolution and provide mental sensations, it changed everything. Feelings made life better. They extended and saved lives. Feelings adapted organisms to imperatives of homeostasis and helped to perform these tasks, providing their value for owners of organisms — which, for example, demonstrates such a phenomenon as conditional avoidance of a certain place. The presence of feelings is closely connected with another development: consciousness, and, specifically, subjectivity.

The value of the knowledge that the senses have for the organism within which they occur, most likely, was the reason that evolution decided to leave them. Feelings affect mental processes from the inside, and they cannot be ignored because of their obvious positive or negative coloring, their origin associated with actions that contribute to health or death, and their ability to capture the owner of the senses and shake it, drawing attention to the situation.

This importance of feelings is demonstrated by the fact that mental sensation does not arise from the simple marking of an object or event in the nervous tissue. Instead, it arises from the multidimensional markup of body-related phenomena, interactively intertwined with phenomena associated with the nervous system. Mental sensations are not “photographs,” but processes that develop over time, telling stories about several micro-events occurring in the body and brain.

You can, of course, imagine how nature could develop without encountering feelings. But that did not happen. The fundamental basis of feelings is so deeply embedded in the system of life support since they have already appeared. All that was required was the appearance of the nervous system making up the mind.

As a result, feelings can annoy or delight us, but they are not needed for this. Feelings are needed to regulate life, to provide information related to the main processes of homeostasis or the social conditions of our life. Feelings tell us about the risks, dangers and current crises that need to be avoided. Plus we can assume that they tell us about the possibilities. They can direct us towards behaviors that improve our homeostasis as a whole, and in the process, they will make us a better version of people more responsible for our own future and for the future of others.

An excerpt from the book "Strange order of things" (2018)