The evolutionary theory of asymmetry V. A. Geodakyan

Asymmetrization is not a private, purely human phenomenon, but a general biological evolutionary phenomenon inherent in all living systems . The evolution of any structures (and information flows) goes from symmetry to asymmetry. For example, such a tendency can be observed in the phylogenesis of flowers and leaves of plants , as well as in the embryogenesis of animals and humans . In phylogenesis, the asymmetry of organisms naturally grows along all axes (I - back-belly, II - nose-tail and III - left-right). V.N. Beklemishev in his classic work identified three types of symmetry ( spherical , radial , bilateral ) and arranged them in an evolutionary series, placing at its beginning a completely asymmetric amoeba . ^[19] Geodakyan believes that the series should begin with the oldest type of ball symmetry and end with the most evolutionally progressive type of triaxial asymmetry (lack of symmetry in all three axes).

Asymmetrization along the top-bottom axis occurred under the influence of the gravitational field. Asymmetrization along the front-back axis occurred during interaction with the spatial field, when rapid movement was required (to be saved from a predator, to catch up with a prey). As a result, the main receptors and the brain were in the front of the body. Asymmetrization along the left-right axis occurs in time, that is, one side (organ) is evolutionarily more advanced, “vanguard” (as it were, in the future), and the other is “rearguard” (in the past).

Triaxially asymmetric organisms retain the two previous asymmetries. Lateral asymmetry appears against the background of the two preceding ones (back – belly and nose – tail) and therefore should spread from front to back. Moreover, lateral asymmetrization, like sexual differentiation, goes from the lowest levels of organization to higher (function → organ → organism → population ).

In the transition from spherical to radial symmetry, asymmetrization occurs along only one axis: from bottom to top. In the subsequent transition to bilateral symmetry, one more axis is added: from back to front. Lateral asymmetrization adds a third axis, right – left. Based on the analysis of experimental data, Geodakyan attributes the lower end, the back, the right hemisphere of the brain and the left side of the body to conservative subsystems. At the same time, flows of new information coming from the environment to the operational subsystems (upper end, front of the body, left hemisphere of the brain and the right side of the body) are directed from top to bottom, from front to back and from left to right for the brain (from right to left for the body). A new trait arises at the operative end and, if it is not needed there, drifts in phylogenesis to a conservative end.

For example, for a linear (one axis of asymmetry) organism - hydra , oriented along the gravitational field, the asymmetrization vector will be directed vertically from bottom to top, that is, from the sole to the mouth surrounded by the corolla of tentacles. The mouth is the operative end where a new sign appears. If a new sign is the brain or receptor, it remains at the operative end. All other signs in the process of phylogenesis should drift to the conservative subsystem. The older the sign, the closer it will be to the sole. Since hydras had all three types of reproduction: the oldest, asexual ( budding ), hermaphroditic, and the youngest, dioecious , the kidneys should be lower, the ovaries higher, and the testes even higher.

Elementary Dominance Unit

Dominance is a form of asymmetry. The dominant hemisphere or organ performs its functions better and is therefore more preferred. The asymmetry of unpaired organs can only be morphological: according to their localization, shape or orientation. In paired organs, asymmetry of sizes and functions is still possible. If an organ has more than one function, then they can have different directions and magnitudes of dominance. For example, a person can be very right-handed in one function (write), weakly left-handed in another (grab), and ambidextr (symmetrical) in the third. Therefore, the elementary unit (carrier) of asymmetry is a function (and not an organ, as is usually considered). Asymmetry of an organ — the vector sum of the asymmetries of its various functions. Asymmetry of an organism is the same sum of asymmetries of organs. Population asymmetry is the asymmetry of the number, variance and lateral dimorphism of subpopulations of asymmetric organisms (say, left-handed and right-handed ). Of the four levels of asymmetry: function, organ, organism and population, in the “pure” form the dominance is only for the functions, the rest are mosaics — some average characteristics determined in total by the number, direction and degree of dominance of their functions.

Conservative - operational specialization of the hemispheres

In relation to the brain, the oldest of its 3 asymmetries — the cortex — is the subcortex, then the forehead is the back of the head and the youngest is lateral. At the same time, the subcortex, the occipital regions and the right hemisphere represent conservative subsystems and functions controlled by the operative hemisphere should be evolutionarily “younger” than functions controlled by the conservative.

Phases of Function Evolution and Hemisphere Dominance

All existing theories believe that the asymmetry of the brain is a consequence of the fact that some functions are in the left hemisphere, while others are in the right, that is, asymmetries create different functions. However, it is known that there are functions that are in the left and right hemispheres. According to the new concept, asymmetry is a consequence of asynchronous evolution, so any function can be in any hemisphere at a certain time. In this case, the asymmetry is created not by the functions themselves, but by the evolutionary phases of these functions.

The dominance of the hemispheres is determined primarily by the amount of information - the hemisphere with more information dominates. In second place is the perfection of execution.

The Age Principle of Hemisphere Specialization in Phylogenesis

In the stable phase of evolution, function is absent in both hemispheres (symmetry). When it becomes necessary to search for a function, the left hemisphere (search) begins to dominate.

New functions first appear in men, and their control centers in the left hemisphere. After many generations, having passed testing and selection there, they pass into the female left hemisphere. The transition from initial bilaterality to left hemisphere (asymmetry) is a dislocation phase of the evolution of a function. The left hemisphere dominates in this phase, since only it has information about newborn function.

When the function has passed the test, information about it passes through the corpus callosum into the right hemisphere, first in men and later in women. If there was one version of the function in the left hemisphere and it fell into the right hemisphere, while remaining also in the left hemisphere, then the amounts of information in the hemispheres are aligned, but dominance translocates to the right hemisphere because of its perfection. If there were several versions of the function in the left hemisphere, then they translocate to the right hemisphere, starting with the earliest versions. In this case, the amount of information may be more in the left hemisphere, and the slow execution of the new version will compete with the fast - the old version. When the amount of information and the perfection of performance begin to prevail in the right hemisphere, a translocation of dominance occurs, that is, the left hemisphere brain for this function turns into the right hemisphere. This is the phase of translocation of function.

If the function is later lost (first in men and later in women), its center is removed first from the left hemisphere, and then from the right, and the asymmetry disappears. This is the relocation phase of the evolution of a function. The right hemisphere dominates in this phase, since it still has information about the function.

When the function is completely lost, the left hemisphere begins to dominate again ( stable phase).

Transitions of functions between hemispheres in ontogenesis

The left hemisphere is social, ontogenetic (phenotypic), so the embryo is almost empty (it is filled after birth). The right hemisphere is biological, phylogenetic (genotypic), so the embryo is full of old information. After birth, sooner or later, the left hemisphere will inevitably equal the right one and be ahead of it. Therefore, at some age, translocation should occur, the right-hemispheric newborn should become a left-hemispheric child. This means that, in principle, three translocations are possible in ontogenesis. The first is postnatal, from embryonic right hemisphere to "children's" left hemisphere (in total, for all functions). The second is the transition of a separate function from children's left hemisphere to mature right hemisphere. And the third - with the loss of function, in the opposite direction: from adult right hemisphere to senile involution (symmetry). With the disappearance of the function, the asymmetry also disappears.

Hemisphere Domination

Asymmetrization of the brain leads to two types of dominance: left hemisphere and right hemisphere. In the vast majority of people, regardless of arm, the left hemisphere dominates (for example, there is a speech center over 95% of right-handed people and about 80% of left-handed people). Hemispheric dominance occurs in approximately 1% of people. About the same number of people with symmetrical hemispheres, in which there is no dominance. The theory interprets hemisphere as an analogue of the genotype, with this the child is born.

The evolutionary role of the corpus callosum, contra and ipsi connections

Contra communication . If we assume that with an improvement in blood supply to the brain , control can improve, then a negative feedback is formed that ensures the symmetry (proportionality) of the hands and other organs. Consequently, the evolutionary meaning of nerve pathway intersection is to ensure lateral symmetry of bilaterally symmetrical and the existing level of asymmetry of organisms. The corpus callosum creates a consistent connection of the hemispheres and dichronism, that is, the asymmetry of the phases of evolution. The evolutionary role of ipsi connections is the creation of adaptability and positive feedback that changes the equilibrium state.

Everything that was said so far related to the pair-wise asymmetry of one paired organ. At the level of two (or more) pairs of paired organs (for example, hemispheres and hands), inter-pair relations create a new type of asymmetry - cis-trans (positional or structural asymmetry). Four different phenotypes arise, depending on whether the dominant hemisphere and arm are located on the same side of the body (cis position) or on the opposite (trans position). Examination of another paired organ, say the legs, will double the number of phenotypes.

Genotypic hemisphere and phenotypic arm

As already mentioned, the theory interprets hemisphere as an analogue of the genotype with which the child is born. The stickiness and asymmetry of other organs, as components of the phenotype , are realized during fetal development, depending on environmental conditions. The genotype is a more fundamental phenomenon than the phenotype, just as the asymmetry of the hemispheres is more fundamental than the asymmetry of the hands. Under optimal conditions, in the first trimester of pregnancy, the dominance of the arm (another organ) appears in a trans position to the dominant hemisphere: the left hemisphere is the right hand, and in extreme conditions, with the psychological and environmental stress of the pregnant mother, in the cis position: the left hemisphere is the left arm. The first is about 10 times more likely than the second.

Not left-right handedness, but cis-trans handedness

An analysis of the frequencies and dispersions of the four combinations of hemisphere and hand shows that left-right hand does not play any role, and changes haphazardly. Of decisive importance is first of all hemisphere, second of all, cis is trans-arm, that is, arm should not be attributed to the body: left or right, which does not matter, but with respect to the dominant hemisphere. It is trans- and cis-individuals that should be considered true right-handed and left-handed, and not right-handed and left-handed, which all existing theories do.

At the population level, evolution creates one subsystem for a stable (optimal) environment, specialized for preserving the (old) and the second for an unstable (extreme) environment, for changing (novations). At the genetic level, this is the female – male sex (individuals, organs, cells, hormones), and at the behavioral and psychological level, the right and left hemispheres, subordinate and dominant functions, organs, trans and cis individuals. By analogy with the three main characteristics of a dioecious population ( sex ratio , gender dispersion and sexual dimorphism ), in the cis-trans society, the ratio of laterality (SL,% cis of individuals), the variance of laterality (DL) and lateral dimorphism (LD) can be distinguished. Usually, three values ​​of these parameters are distinguished for three moments of ontogenesis: for zygotes , primary (SL1), for newborns, secondary (SL2) and adult individuals of reproductive age, tertiary (SL3).

By analogy with the “Ecological rule of sex differentiation”, Geodakyan formulates the “Ecological rule of lateral differentiation”, which describes the behavior of cis-trans subpopulations (left-handed and right-handed) in a stable and variable environment, regulating the behavioral evolutionary plasticity of society.

Regulation of Behavioral Dominance

According to the generalized ecological rule, the role of conservative subsystems (females, right hemisphere, left hemisphere dominance, trans individuals) should grow in an optimal environment, and in the extreme, on the contrary, operational, reformatory (males, left hemisphere, right hemisphere, cis individuals). By gender, this is manifested in the transition from matriarchy to patriarchy . For example, in elephants , in an optimal environment, the herd is led by an old female, and in an extreme environment by a male. ^[5] Matriarchy is more common on islands, in forest and mountain isolates (where there are no neighbors and wars). The same thing in asymmetry: in a calm environment, the sociocultural, rational, but slow, left hemisphere dominates, and in a stressful situation, a switch to biological, automatic, fast right takes place.

The existence of information flows causing asymmetries

Hydras have the oldest reproductive organs located lower than everything, then slightly higher, the ovaries, and even higher the testes. In earthworms, the ovaries are located closer to the tail (in the 13th segment) than the testes (in the 10th segment). The black color of the back of the initially white penguin appears on the head, then spreads to the tail. In whales, cubs of some species darken from the head (gray whales), others lighten ( beluga whales ). ^[20] Damage to the frontal region of the brain in women and the occipital region in men with aphasia and apraxia ^[21] suggests that in women the centers of these diseases are still in the anterior lobe, and in men already in the posterior lobe.

Hemisphere Functional Distribution and Brain Asymmetry

Most left hemisphere functions are clearly evolutionarily younger than right hemisphere functions. The left hemisphere (for normal right-handed ones) serves for the semantic perception and reproduction of speech, writing, subtle motor control of the fingers of both hands, self-awareness, arithmetic counting, logical, analytical, abstract thinking, musical composition, space of colors, positive emotions. It processes information sequentially, understands well tense, verbs, is capable of false “statements”, and turning it off leads to depression. The right hemisphere is for spatial-visual functions, intuition, music, intonational features of speech, gross movements of the whole arm, emotionally holistic perception, synthetic, situational thinking, negative emotions. It processes information at once (holistically), almost does not understand verbs, abstract terms, is not capable of false statements, and turning it off leads to euphoria. ^{[22] [23] [24] [25]} Geodakyan compares emotions: negative – positive; understanding: space – time, nouns – verbs, color space; ability of utterances: true – false. Both in phylogenesis and ontogenesis, the former appear earlier than the latter. In newborns, crying is preceded by a smile; in kittens, a mournful squeak is ahead of a purr ; in puppies, whining begins three months before tail wagging. With functional inhibition of the brain, negative emotions disappear last and are restored first, ^[22] which means a more ancient age. Understanding space is easier than time; nouns are simpler than verbs; true statements are easier than false. Orientation in space comes earlier than in time; the first words of the child are more often nouns, the lie appears later. The space of flowers, also, apparently, can be considered an evolutionarily new acquisition. The characters of the Iliad and Odyssey used a very narrow spectrum of colors. ^[2]

The left eye is more sensitive to simple signals (flash of light), and the right eye is more sensitive to complex ones (words, numbers) ^[26] (old and new stimuli). The left eye is more sensitive to ordinary words, and the right eye to brands (old and new words). Environmental sounds (the sound of rain, sea, dog barking, coughing, etc.) hear the left ear better, and semantic (words, numbers) - the right one ^{[27] [28] [29]} (old and new sounds). In humans, according to speech dichotic signals, in the first days there is an advantage of the right ear, and after a week - the left. ^{[24] The} left hand recognizes familiar objects to the touch better, and the right ^{[26] [30]} (old and new objects) are better recognized by touch.

Asymmetry of paired organs

According to Geodakyan, with the specialization of paired organs, the right organ acquires a new function, and the left one retains the old one. As an example, he cites the fact that mainly the left ovary ovulates in dolphins , while in the sperm whale only the left nostril is preserved. ^[20]

Monkeys take food more often with their left hand, and manipulate it with their right hand, ^{[31] [32] [33] [34]} since right-handedness in “instrumental” (new) functions should be higher than in “non-instrumental” (old) ones. Siamese, chimpanzees, orangutans, gorillas prefer the right limb to start ground movement, ^[31] - a new function.

The fact that children under 12 years old have more bone of the right thigh, and after 13 left (the transition of “children's right-legacy” to “adult left-legged”) ^[35] is explained by the translocation of the control center of the upright movement from the left hemisphere to the right. Reverse translocation is observed for lost functions, for example, with a fading sign of smell in a person or with a grasping reflex that is stronger in the left hand. ^[31]

The high dispersion of left-handed people is confirmed by their increased percentage (like men) among geniuses and weak-minded (children who are unable to learn to read are left-handed boys), their shorter life expectancy (almost 9 years) and a low breeding index (in left-handed people by the age of 45 in an average of 1.62 children, right-handed - 2.03), increased susceptibility to many diseases (immune, nervous) and accidents. This is also indicated by the results of 7-year anthropometric studies of the frequencies of extreme phenotypes depending on arm and gender in 6,000 children by height, weight and head circumference. For all three parameters, the variance of the left-handed was wider than that of the right-handed. Of the 42 groups (2 genders, 3 traits, 7 ages), left-handed people had a higher variance in 33, right-handed people in 5, and in 4 groups the variances were equal. ^[36]

The combined use of theories of gender and asymmetry allows us to relate these two phenomena and make some predictions. Some of them are confirmed by well-known literature data and specially delivered experiments, while others have not yet been verified.

• If there are dioecious triaxially asymmetric plants, then they should have sexual dimorphism in all respects with lateral dimorphism (the rule of conjugate dimorphisms).
• In bassets and spaniels, the longest ear should be right in males, and the shortest — left in females.
• In all cases of environmental and psychological stress and discomfort: among interracial, ethnic hybrids, in highland, seismic, ecologically disadvantaged areas, after earthquakes, wars, genocide, famine, relocations and other natural and social shifts, male fertility (and mortality) should increase gender and fertility of lefties.
• Since the sense of smell in a person is lost, it should be better in the right hemisphere than in the left. It also follows from gender theory that women should have a better sense of smell than men, and that children should have better smells than adults.
• People’s teeth are getting smaller. Therefore, the smallest teeth should be in men on the right, and the largest in women on the left.
• Since the eyes in the process of evolution gradually moved from the sides (like horses) to the face, in men, on average, the eyes are slightly closer to the nose than in women. In this case, the right eye is always a little closer to the nose than the left, as well as the right ear is usually slightly higher than the left. Peripheral vision in women is better developed, and the eye is worse than in men.
• Unconditioned reflexes are older than conditioned reflexes, so they should be stronger on the left, and conditioned ones on the right.
• The transition (translocation) of dominance from the left hemisphere to the right was confirmed when studying the development of a conditioned reflex in humans, dogs, and cats by the method of evoked potentials and EEG. ^[7] A similar translocation was later discovered in the hypothalamus. ^[eight]
• Since the right hemisphere is biological, species, phylogenetic, and the left is sociocultural, ethnic, and ontogenetic, the variance in the population should be greater in the left hemispheres.

This prediction was confirmed on three ethnic groups (Indians, Negroes and whites, total 1220 people) in America. ^[24] and in the study of the northern peoples of Russia. ^[37]

• The transition in phylo- and ontogenesis from ambidextria to right-handedness and further to left-handedness allows us to predict the existence of a right-handed intermediate phase in all functions of the left hand, and the absence of a similar left-handed phase in functions of the right hand.
• Learning a new skill in the left-handed right hand should be more effective with the left hand than with the right.
• According to the new functions of the legs, say, to write or draw in the sand, to take and shift objects, the theory predicts a legacy.
• If you make the first whole face of the two left halves of the portrait, and the second of the two right halves, the first will look more like a mother and sisters, the second will look like a father and brothers.
• Not only in the “manual” (boxing, golf, tennis), but also in any (“non-manual”) sport (chess, football, running, jumping) there should be many left-handed players among the champions.
• Diseases and developmental anomalies of paired organs, having an “atavistic” nature, are more likely to occur in women, somatic — on the left, cerebral (mental) —right, and “futuristic” (“searching,” diseases of the century, civilization, urbanization), on the contrary, in men , somatic — on the right, mental on the left.
• The psychology of trans individuals (right-handed people) should be typically female, adaptive in a stable environment, a rational conservation strategy (conservatism, law-abiding conformism, collectivism). The psychology of cis individuals (left-handed people) is typically masculine, adaptive in a volatile environment, an irrational strategy of change (reformers, dissenters, individualists, rebels, extremists, outcasts who are out of step). Among the leaders of associations should be more male left-handed people.

Quite popular in the West and widely quoted theory of Gershwind and Galaburda, linking left-handedness with an increased level of testosterone, discusses the mechanisms of the phenomenon, which are almost not discussed in the Geodakyan theory. ^[38] V. Geodakyan himself noted that theories contradict the data of Z. V. Denisova, which showed that the centers of music and humor are in the right hemisphere, ^[22] while the asymmetry theory in the right hemisphere should be old, “ non-creative ”versions, and creative ones should be in the left hemisphere. ^[2]

Also, at first glance, the theory contradicts the asymmetry of the testicles . In theory, the right testicle should lead when lowering from the abdominal cavity and, accordingly, should fall below. Since it is noted that in a person the right testicle is larger and heavier than the left, it can also be assumed that it will be located lower. ^[39] However, in a number of works it was found that in humans, the right testicle is more often located above the left and has more developed muscles, which can explain the observed picture. ^{[39] [40] [41] [42]}

• Predominant hand
• Left handed
• Righty
• Ambidextr
• Symmetry (biology)
• Radial symmetry
• Laterality
• Chirality (chemistry)
• Interhemispheric asymmetry
• The evolutionary theory of sex V. A. Geodakyan
• The evolutionary theory of nomadic genes V. A. Geodakyan

• Theory of asymmetrization of organisms, brain and paired organs (I)