Evolutionary Theory of Asymmetrization of Organisms, Brain and Body

Single organs can have asymmetry on location, shape or orientation. Paired organs can also have asymmetry on size and functions.

Dominant vs. subordinate— In a pair, one organ is dominant or driving, and the other is subordinate or driven. Typically, the dominant organ has larger bones and muscles, and it fulfills its functions better (and thus is preferred). Sometimes the organs are identical; in the case of hands, this is ambidexterity.

Usually dominance is related to an organ. However if organ has many functions, they can have different direction and extent of dominance. For example, a person can be strongly right handed on writing, slightly left handed on throwing things and ambidextrous on another function.

Therefore a function (not an organ as usually considered) is the smallest element of asymmetry. Function is the only level of asymmetry that has “pure” form of dominance.

Lateral asymmetrization goes from “bottom to top” (function ® organ ® organism ® population). The organ, organism and population are mosaics, i.e. the asymmetry of an organ consists of a vector sum of the asymmetry of its different functions. Asymmetry of the organism is again the sum of the organs’ asymmetries. Asymmetry of a population is the asymmetry of the ratio, variance and lateral dimorphism of subpopulations of asymmetric organisms (left and right handed).

Asymmetrization is not especially-human phenomenon, but general evolutionary phenomenon inherent to all live systems. Therefore all attempts to explain brain asymmetry as a unique human feature (speech, right handedness, and self-consciousness) and also as pathology or birth defect need to be abandoned.

For the brain the most ancient asymmetry is cortex – subcortex, then forehead – back of the head. The lateral asymmetry is the youngest.

Functions controlled by an operative hemisphere should be evolutionary “younger” than functions controlled by a conservative hemisphere.

In the left hemisphere are located: perception of meaning and reconstruction of speech, writing, self-awareness, fine motor control of the fingers of both hands, logical, analytical, abstract thinking, arithmetical calculation, musical composition, color range, positive emotions. It understands well time, verbs, is capable of false statements. To the right hemisphere belong spatial-visual capacities, intuition, music, speech intonation, coarse movement of all extremities, integral perception, negative emotions, humor. It understands little of verbs, abstract terms (health, spite, joy, religion), and is not capable of false statements.

The evolutionary “age” of some other functions is not so obvious. For example, emotions: negative-positive, understanding, spatial-temporal, noun-verb, statements, true-false. Both in phylogeny and in ontogeny the first appear earlier than the second. In newborns crying precedes smiling, in kittens plaintive whining, purring, in puppies whimpers begin three months earlier than tail wagging. Moreover, with the functional suppression of the brain negative emotions disappear in the latter and are established in the first. If one thinks of the thinking and vocabulary of child (or of savages), then it is easy to be convinced that the understanding of space is simpler than that of time, nouns are simpler than verbs, true statements simpler than the lie. The first words of a child are nouns, slyness and lies appear later, orientation in space also occurs earlier than in time. Color range also obviously can be considered as an evolutionarily young acquisition. The characters of the “Iliad” and “Odyssey” made use of a very narrow range of colors.

Analysis of the specialization of the hemispheres makes it possible to conclude that left hemisphere should be considered an operative subsystem, and right hemisphere—a conservative one. The new information from the environment goes first to the left hemisphere then to the right hemisphere:

	LH RH
Environment

[The Evolutionary Theory of Sex (ETS): the information from the environment goes first to the males then to the females:
environment → male sex → female sex ]

Asymmetrization along the axis “left – right” according to the new theory occurs in time, so the left hemisphere is a “vanguard” (as, already in the future) and right hemisphere is a “rear-guard” (yet in the past).

“Age” principle of localization of centers in hemispheres. Centers for the administration of new functions first appear in the left hemisphere. After verification they are translocated (get transferred) into the right hemisphere.
[ETS: new genes appear in the male genome, stay there for many generations, and after verification get transferred to females]

In the Phylogeny of any function it is possible to allocate three forms of localization of its center. Young (new) functions are located only in the left hemisphere (socio-cultural). Mature functions—(most functions that have already been verified) are located both in the left (later “versions”) and in the right (earlier “versions”) hemisphere. Old functions that are already lost by left hemisphere are located only in the right hemisphere (biological).

Under the new theory the left hemisphere is social, ontogenetic (phenotypical) therefore at an embryo it is almost empty (and gets filled after birth). Right hemisphere is biological, phylogenetic (genotypical), and therefore at an embryo it is full of the old information. After birth, sooner or later, the left hemisphere will inevitably catch up with the right one and will surpass it. So, at some point the translocation should occur— the right hemisphere newborn should become the left hemisphere child. In the Ontogeny there can be, basically, three translocations. The first—postnatal—from right hemispheric embryo to left hemispheric child (totally, on all functions). The second—transition of a separate function from a child left hemisphereness to adult right hemisphereness. And the third—at loss of a function, in the opposite direction: from adult right hemisphereness to senile involution (symmetry). If the function undergoes reduction, there will be no asymmetry, an example—sense of smell at men (by 80 years 85 % of nervous fibers will atrophy!).

Translocation—the transition of function domination from one hemisphere into another.

	Stages of Phylogeny	Translocation	Dominates
5	stable, symmetry, character φ is absent		Better search	LH
4	evolution, asymmetry, character φ is eliminated		Information quantity	RH
3	stable, symmetry, character φ is present		Perfection	RH
2	evolution, asymmetry, character φ is created		Information quantity	LH
1	stable, symmetry, character φ is absent		Better search	LH

In stable phase of evolution (1) when the function is absent, and the search is more important, the left hemisphere responsible for the search will dominate.

In the phase of evolution (2), the left hemisphere will dominate since only the left hemisphere has the information about the newborn function.

In stable phase (3), when the information was transferred into the right hemisphere but is still retained in the left one, the right hemisphere (fast and more flawless) will dominate.

In the phase of elimination or degradation of a function (4), the right hemisphere will dominate since it still has the information about the function.

And in stable phase of evolution (5) when the function is lost, the left hemisphere starts dominating again.

Asymmetrization of the brain leads to two types of dominance: left hemisphere (LH) and right hemisphere (RH).

Vast majority of humans (99%) have left hemisphere dominance. Theory interprets hemisphere dominance as an analogy to a genotype; the child is born with certain type of dominance.

The right hemisphere should control embryogenesis (old system) as a whole (morphology: a skull, a skeleton). And, operated by the right hemisphere, the left part of a body, should be larger, than the right one! The fetus has a few new attributes and the left hemisphere (social, according to the theory) is almost empty. One of such attributes—a sucking reflex (analogue and almost the coeval of a placenta). As is known, the fetus in a womb of mother sucks the big finger. So, it should be the finger of the right hand operated by the left hemisphere. In an ultrasound study of fetal thumb sucking, it was found that about 90% of fetuses above 15 weeks gestational age suck their right thumb predominantly (Hepper, e.a., 1991). The factors producing manual asymmetries in early fetal life remain unknown (Michel, 1983).