On Human Thinking and Longevity

Why we won't live long if we delegate thinking to robots

The concept of biotic regulation is inherently interdisciplinary and builds, among other things, on research into the energetics of life (see here for a brief overview and publication list). Much of that work preceded the biotic pump, which has since become our main focus. Yet understanding how natural ecosystems keep Earth habitable, and how we can avoid interfering, cannot be achieved within the limits of any single discipline.

Today, I’d like to discuss how the remarkable longevity of humans—about three to four times that of similarly sized non-primate mammals—might help explain the nature of human thinking and its environmental implications. This includes why major discoveries are typically made by individuals rather than groups, why thinking less could actually shorten our lives, and why we are so much less ecologically grounded than other species in the biosphere.

Humans live long. Data on maximum recorded longevity from AnAge Build 15, downloaded from https://genomics.senescence.info/download.html#anage Note that bats also live long (and so do birds, not shown here). Flight should be something intellectually special.

In a nutshell, the idea is as follows. While most body cells can regenerate thanks to the effectively immortal DNA that carries the instructions, memory stored in the brain is different. It is not encoded in discrete, exactly copyable units — so duplicating brain cells, i.e. growing them anew, would erase the information. Once the brain cells die, so does the person.

The only way to extend the lifespan of memory is to continuously copy it across many relatively independent memory modules within the brain. A person remains alive as long as at least one memory module containing the full set of essential memory information remains functional. Just as the expected maximum lifespan among a group is longer than the average individual lifespan, this internal redundancy will increase the overall persistence of human memory and thereby extend human life.

Thinking, then, is the process of sharing and copying information between these memory modules. Because this process is analog rather than digital, new connections can emerge in the act of sharing, sometimes leading to scientific discoveries.

If we assume a simple model of exponential mortality, then explaining why humans live about four times longer than similarly sized mammals requires about 50 such memory modules (not incidentally, a number close in its order of magnitude to Dunbar’s). This reflects the number of internal “selves” that together strive to keep us alive. Thinking is what makes us live longer.

The main problem of life

It is sometimes said that nothing in biology makes sense except in the light of evolution. Within the framework of biotic regulation, this statement is comparable to claiming that nothing in climate change matters except the accumulation of CO₂. In reality, the central challenge of life is not how to evolve—a rare event that occurs only once every few million years for a species—but how to preserve life’s extraordinary complexity against constant degradation into chaos, which is a daily, routine process.

The genetic information of life decays relatively slowly: errors in DNA copying occur roughly once in every ten billion "letters," suggesting that a complete breakdown would take millions or even billions of years. However, life also depends on non-genetic memory information. The question is: how can this kind of information be stabilized?

Why don’t plants have heads?

The functioning of plants and fungi, which do not locomote, are determined by hereditary genetic information encoded in DNA molecules. In contrast, all locomotive animals that have to move in search of food possess, in addition, non-genetic memory information accumulated during their lifetime. Locomotion requires memory.

Memory information accumulates at a rate much faster than the rate of cell division. Therefore, the carriers of memory information must be certain molecular structures, just like DNA molecules are carriers of genetic information. It is still unknown which molecular agents in the brain are responsible for the accumulation of non-genetic memory information. The mass of the molecular carriers of memory information in the brain may be as much smaller than the mass of the whole brain as the mass a DNA macromolecule is compared to a single cell—that is, by a factor of a thousand.

This non-genetic memory information, which varies greatly among individuals of all animal species and humans, including identical twins, constitutes what is commonly referred to as the soul of the individual.

Memory information is acquired by the animal through its interaction with the environment via its sensory organs like sight, hearing, smell, touch, and taste. These organs are connected by neural "wires" to the memory storage, which, to minimize the risk of damage to these connections, must be located as close as possible. Therefore, in most locomotive animals, all sensory organs are situated near the memory storage, the brain, within a special part of the animal body: the head. An animal’s memory is formed throughout its life and disintegrates upon its death.

Organisms of non-motile species, such as fungi and plants, do not accumulate non-genetic memory information over the course of their lives, do not need a head and do not have it.

Culture as humanity’s collective non-genetic memory

Humans differ from all other animals in their unique ability to pass on information accumulated during life to the memory of future generations, thereby forming a shared cultural heritage.

While rudimentary forms of culture can be found in some animal species, they do not offer a clear advantage over those that rely solely on genetic information. For example, birds do not teach their offspring how to build nests. In contrast, human culture allows accumulated knowledge to outlive the individual, continuing to exist in the memory of others. In this sense, a part of the human soul, unlike that of animals, is immortal, forming the basis for many religious beliefs in an afterlife.

However, what is truly immortal is the memory of the outstanding individuals who have left a lasting mark on human culture. The memory of Homer, Archimedes, Leonardo da Vinci, Mozart, Beethoven, Pushkin, Chekhov, Newton, Maxwell, and Einstein has endured through the centuries. It often feels as if these figures are still among us, living alongside us as contemporaries.

Memory information can accumulate only through an individual’s interaction with the environment, including with others of the same species. During sleep or unconscious states, memory does not engage with the environment and thus does not gain new information. However, a person can process information already stored in memory at any time—without external input—leading to scientific discoveries or the creation of musical, literary, and artistic works. This internal process is what we call thinking. It may occur independently of any interaction with the outside world.

But how does thinking actually happen? Does it exist in other animals, or is it a uniquely human ability?

Memory and lifespan of individuals in animal populations

Many tissues in our body routinely renew through cell division. However, the nerve cells of the brain, which serve as the storage of memory, do not divide—if they did, the stored information would be lost. (Interestingly, heart cells also regenerate very poorly—less than 1% annually over a lifetime—and most of our cardiomyocytes, like neurons, remain with us throughout life. Theoretically, then, the heart could also serve as a store of individual memory.)

The lifespan of all locomotive animals is therefore limited by the lifespan of the nerve cells in their brains. Since memory is carried by molecular structures within these brain cells, the decay of memory should follow the same statistical laws that govern the radioactive decay of excited states in atoms, molecules, and atomic nuclei, leading to gradual memory loss over time.

According to this law, the number of remaining excited molecular states is tied to the half-life T₂, which is the time it takes for the number of excited molecules to decrease by half. After the initial number of excited molecules N is reduced by half, the remaining half is again halved over the same half-life period T₂, and so on.

That is, the reduction in the initial number of excited molecules N follows a geometric progression of the form:
N(t) = N × 2^(–t/T₂)

The dying of individuals in most animal species under natural conditions can occur in the same way. This corresponds to age-independent mortality. Disclaimer: The actual mortality is more complicated and depends on age and the living conditions (e.g., wild versus captive). Many species of animals and plants have a special genetic program limiting the individual's lifespan. For example, in annual plants and many insects in temperate zones where winter occurs, all individuals live less than one year, and then they all die at once. Meanwhile closely related species of the same size in the tropics can live for many years. Here we will discuss the exponential decay for its conceptual simplicity.

If you select a large group of animals, then after a certain time, half of this group remains alive. After that, after the same amount of time, a quarter of the original group remains alive, and so on. Instead of the half-life, one can consider the time for the group size to decrease by 3 or 4 times. Such a time will be longer than the half-life.

The average lifespan of the individuals in the group, equal to the sum of the lifetimes of all individuals divided by the group size, coincides with the time for the group size to decrease by e = 2.71828... ≈ 3 times. The number e, the base of natural logarithms, was introduced by the Swiss mathematician Leonhard Euler (1707–1783), who made many of his discoveries while living and working in St. Petersburg, Russia. Exponential function e^x is the only function that does not change under differentiation and integration. The half-life of a group of animals is proportional (with a coefficient of 0.7) to the average lifespan of an individual of the species.

If this average lifespan is, for example, 15 years (half-life period of 10 years), then in the animal population, one can find individuals aged 20 years, but there will be twice as few of them; individuals aged 30 years, but four times fewer; and even individuals aged 40 years—there will be eight times fewer of them. Individuals aged 100 years in a species with an average lifespan of 15 years should be a thousand times fewer, i.e., they practically do not occur in the population.

Human lifespan and the difference between humans and animals

The average human lifespan is about four times longer than the average lifespan of all other (non-primate) mammals of similar body size. While the average human lifespan is about 80 years (with a corresponding half-life of around 60 years), there are virtually no people who live twice as long (120 years), let alone three times (180 years) or four times (240 years) as long.

The brain’s energy expenditure—that is, the power it consumes per unit mass—is several times higher than the average for the human body (though the heart and kidneys are even more metabolically active). This high energy demand explains why we can withstand frost with an exposed face while the rest of the body is carefully bundled up. It also accounts for why the head tends to sweat more than other parts during physical exertion. In short, brain function is a highly energy-intensive process.

The nerve cells of the human brain are structurally and energetically identical to those of other mammals.

Glucose use per unit time by neurons in different species vs neuron density, according to Herculano-Houzel (2011), who concluded as follows: “Most importantly, the cross-species comparison of the average energy cost per neuron thus defined indicates that this cost does not scale significantly with brain size, neuronal size, or number of neurons. Rather, it suggests that, within structures such as the cerebral cortex and cerebellum, neurons are allotted a fixed energy budget, regardless of their size, across species. … These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons.”

Therefore, the decay rate of memory information stored in these similar neurons should also be the same. But why, then, is the lifespan of an individual human not governed by the same half-life decay law as in other mammals? How can the average human lifespan be four times longer?

The answer to these two questions can be found if we assume the following perspective:

• A non-human mammal population is effectively a collection of individual brains.

• The individual lifespan of each brain coincides with the lifespan of the animal and is distributed according to the law of exponential decay.

• In humans, however, the brain functions as a population of autonomous memory modules, each equivalent to one animal brain and containing a full set of memory information.

• These autonomous memory modules degenerate according to the same half-life principle. Yet as long as at least one intact module remains in the human brain, carrying the full (or nearly full) memory, the individual remains alive.

Now, it’s not difficult to calculate the initial number of autonomous memory modules required to extend the average human lifespan by a factor of four compared to the lifespan of an animal with only one memory module.

• Let τ (tau) be the average lifespan of one memory module (equivalent to the lifespan of animal brain).

• For animals, τ equals the average individual lifespan.

• For humans, the average lifespan T = 4τ.

The time τ is the period during which a group of newly born animals—or, equivalently, animal memory modules—reduces in number by a factor of e ≈ 2.7.

Let N be the number of autonomous brain regions at the start of human life.
By the end of life, due to decay, this number reduces to 1: 1 = N × e^(–4τ/τ). From this we find N ≈ 50. Thus, the human brain must contain about 50 independent memory modules in order to extend lifespan fourfold compared to other mammals that, under our assumption, have only one.

The complex organization of living systems is constantly upheld by a continuous expenditure of energy, which repairs and regenerates deteriorating body structures. For example, our skin heals after cuts, restoring itself to its original state, including the unique fingerprint patterns. However, the degeneration of the inherently non-renewable brain makes it biologically pointless to prevent or slow the breakdown of other body parts in animals. The body's metabolism merely ensures that the organism does not decay faster than the irreversible deterioration of the brain.

During human evolution, the emergence of autonomous memory modules responsible for thinking did not alter the decay rate of the rest of the body. The lifespan of early, uncivilized humans (apart from a longer childhood) still followed the same half-life pattern seen in animals. The average human lifespan remained relatively short.

It was only with the advent of modern lifestyles that freed people from hard physical work that the degeneration of the body’s other systems could be slowed to match the rate of brain decline. As a result, people began to reach a common maximum age, after which death occurs abruptly.

By contrast, any significant extension of the average lifespan of locomotive non-human mammals through medicine is largely impossible, as their lives are constrained by the longevity of the brain’s irreplaceable nerve cells, which store all memory information in a single, unrecoverable copy.

Meanwhile, organisms that do not rely heavily on lifetime memory—such as plants or non-locomotive animals—can, in principle, be biologically immortal, at least on timescales where genetic degradation of DNA is negligible.

The Nature of Thinking

So, a young person possesses a brain equivalent to 50 brains of similarly sized mammals. Each autonomous memory module must contain all memory information. Any information a person receives from the environment through sensory organs must be distributed among all these autonomous modules in the brain. This process of information distribution can occur continuously and independently of contact with the outside world. During this distribution, connections between different types of information may be discovered, leading to scientific and cultural insights. This very process of information copying and sharing between autonomous memory modules is what we call thinking.

This concept of thinking helps explain the uniquely human phenomenon of cultural knowledge accumulation. Once the brain learns to copy and share information between its own memory modules, it matters little whether the sharing happens within one brain or between individuals. The habit of sharing, and being shared, information has thus become a defining feature of our species.

We thus arrive at the conclusion that thinking in the above sense is a unique human trait. Other mammals having only one memory module do not possess it.

Any memory elements encoded in molecular structures are subject to random decay. The breakdown and loss of memory elements essential for an animal’s survival ultimately lead to its death. For example, a migratory bird that returns to the same tree hollow for years would lose its ability to reproduce if it forgot the hollow’s location.

In a brain composed of fifty autonomous modules, each holding the same memory information, decay also occurs, but in different places across modules due to its randomness. The chance of the same element decaying in all modules at once is extremely small. Thus, the loss of memory elements in one module is quickly compensated by copying from others through their interaction during the thinking process.

As a result, humans who have not reached the maximum biological age can preserve all accumulated memory information. Active thinking, i.e., the copying of information between the brain’s autonomous memory moduels, counteracts the decay of memory and increases human lifespan.

Thinking fades in the very elderly, who have lost most of their memory modules. Yet it is precisely older people who retain the largest store of memory information accumulated over their long lives—their memory modules are fewer, but very full.

Human brain and society

The fifty autonomous memory modules in a single head cannot be completely identical; they vary slightly in their level of organization. This allows for competitive interaction, as well as for cooperation, among these modules. The number of autonomous memory modules in a person—around 50—corresponds to the average number of individuals in natural animal groups and, by the order of magnitude, matches Dunbar’s number in humans.

The interaction among memory modules within the brain may partly or even fully satisfy the innate human need for social engagement (both competition and cooperation). This could explain why, despite our deeply social nature, some individuals are able to retreat from society in one way or another and still live productive, creative lives. The lives of great scientists, writers, composers, philosophers, and spiritual hermits, whose relative solitude led to enduring contributions to human culture, offer striking examples.

The autonomous memory modules within a single person's brain share a common origin, enabling seamless mutual understanding. Their interactions occur along the shortest possible paths—routes unattainable in communication between different individuals. A "brainstorm" is more effective when it happens within one capable mind than across many. This may explain why the greatest scientific discoveries, philosophical systems, and religious teachings have invariably been the work of solitary individuals.

Each of the outstanding names mentioned earlier—and many others, such as Pasteur, Shakespeare, Bach, Buddha, Jesus Christ, and Muhammad—belonged to an individual, not a group. Even with the remarkable advances in information exchange and the rise of the Internet, major scientific and cultural breakthroughs continue to come from individuals, not large collectives.

Also consider that copying information implies sharing it, but sharing and copying are not the same. Within a single brain, it is important to ensure that all memory modules carry the same information to protect against random loss—so copying is essential. However, when copying begins to dominate information sharing between different brains, we end up with a society where everyone holds the same opinion and no dissent is tolerated.

Why, for example, are we pleased when others agree with us and uncomfortable when they don’t? In the latter case, we sense that the “copying” of our information has been imperfect—a risky scenario if it were happening within one brain.

A collective is a powerful social force. A group bound by a shared cultural ideology can shield society from the influence of new contributions made by individuals. Many scientific and artistic achievements were recognized only after their creators had died, as the dominant professional community often met them with hostility or failed to understand their work. Countless creations by musicians, artists, and scientists were lost to society for generations—and some, no doubt, are lost forever. A deeper understanding of the nature of thinking could help humanity move beyond destructive collective patterns that impede cultural progress.

Finally, let us also note that thinking—understood as the internal copying of information between memory modules within a single brain—diverts both energy and time away from interacting with the external environment. From the perspective of biotic regulation, this makes humans inferior to other members of the biosphere, who can dedicate all their resources to meaningful participation in ecosystem processes. Indeed, much of the cultural knowledge generated by human thought has, in fact, been far from biosphere-friendly. Compared to our animal counterparts, thinking makes us more introverted and less grounded in ecological reality, heightening our propensity to destroy the ecosystems that sustain our lives. Once again, understanding the nature of human thinking, and making it more biosphere-oriented, could help us avoid the worst outcomes.

Further reading

Gorshkov V.G. (1995) Physical and biological bases of life stability. Man, biota, environment. Springer, Berlin.

Gorshkov V.G., Makarieva A.M. (2007) Human thinking, longevity and the problems of living matter orderliness. Ecology and Education, No. 3-4 (2007), 7-11. (In Russian)