Theory of Asynchronous Evolution

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The Evolutionary Theory of Sex: Rules

“Ecological rule of sexual differentiation”: Major population parameters—sex ratio, variation and sexual dimorphism—are not constant but rather closely linked with environment defining evolutionary plasticity of a species. In stable environment they reveal decreasing plasticity, while in extreme environment they show opposite trend. Some species, like Crustacean, switch from one reproduction style to another (from parthenogenesis in optimal conditions to dioecious in extreme conditions). Most of the species with separate sexes have smoother transition: in optimal conditions the main characteristics are low (fewer men are being born, their dispersion narrows, and the sexual dimorphism decreases) and in extreme conditions they grow.

Stress acts as a regulatory mechanism of evolutionary plasticity. Since the ecological stress brings to the rise of these parameters, they can be considered indicators of the ecological niche. In this regard it is explicable that the rate of boy births in Kara-Kalpak for the past 10 years grew 5%. According to the ecological rule, the main parameters have to grow when natural or social disasters happen (earthquakes, wars, hunger, and resettlement).

Criterion of character’s evolution: monomorphic characters are stable while dimorphic characters undergo evolution.

“Phylogenetic rule of sexual dimorphism”: Evolution of a trait is directed from its female form to the male. The characters which often appear and are more pronounced in females ought to be of the "atavistic" nature, and those more often manifested in males — of the "futuristic" one (search).

The rule is easy to verify on the farm animals and plants that were artificially selected and induced into evolution by a human being. The selection features must be more dominant in males. The examples are numerous: with the meat producers such as pigs, sheep, cows, birds, the males grow faster, gain weight and provide better meat than females, the stallions are better than mares in sporting and physical labor features, the fine-fleeced rams provide 1.5-2 times more fleece what the sheep produce, among the fur producers males have better fur than females, the male silkworm produces 20% more silk, etc.

The phylogenetic rule of sexual dimorphism was also successfully verified up on a large group (173 species) of lower Crustaceae (Geodakian V. A., Smirnov N. N., 1968).

“Phylogenetic rule of variation”: If the variation of a trait is larger in males — the phase of its evolution is divergent; if variations are equal – the phase is parallel; if variation is higher in females — the phase is convergent.

Rule to define average speed of character’s evolution (V): V= dimorphism/dichronism

“Ontogenetic rule of sexual dimorphism”: In individual development a character evolves from its female form to the male one.
If there is population sexual dimorphism according to a certain trait, then during ontogeny (with age), this trait changes, as a rule, from the female form to the male, i.e., the female form of a trait is more characteristic of the initial, juvenile stage, while the male form is more characteristic of the definitive stage (mature, adult). In other words, female forms of traits should, as a rule, weaken with age, while male forms should intensify.

Verification of this rule in two dozens of anthropometrical features fully corroborates with the theoretical prediction. Clear example – the development of horns in different deer and antelope species: the larger the horns, the lower in Ontogeny males acquire them before females. The same dependency is proved by the age latency in the functional asymmetrical brain development among women, as discovered by S. Vitelzon (1976). She explored the skills of 200 right-handed children to recognize the subject based on its shape by touching it with right and left hands and came to the conclusion that boys at age 6 have right-brain specialization, while girls are symmetric until 13.

About twenty anthropological characters for which the data on both sexual dimorphism and ontogenetic dynamics were obtained prove completely the regularity predicted by the theory. These characters are: relative length of legs, forearm, fingers, head index, tooth arch, epicanthus, aquiline nose, erythrocyte concentration in the blood, pulse frequency, brain asymmetry, norm and time of reaction, olfaction, perception of bitter taste of phenylthiourea and others (Roginskij Ja.Ja., M.G.Levin, 1963; Harrison G.A., e.a. 1964)

“Rule of reciprocal effects”: Hybrids show paternal dominance (“paternal effect”) in divergent characters and maternal dominance in the convergent one. In particular, the paternal effect should exist on all economically valuable traits at agricultural animals and plants.

“Teratological rule of sexual dimorphism”: Atavistic anomalies are more frequent in females while “futuristic” ones occur in males.

The teratological rule of sexual dimorphism easily explains a different spectrum of congenital anomalies of development of heart and the main vessels, observed at children of a different sex. Elements of defects with which girls are born more frequently, have the “atavistic” nature (ostium secundum and patent ductus arteriosus). They can be found as a norm at human phylogenetic predecessors and at human embryos at last stages of development. Elements of man's defects (stenoses, coarctations, transpositions of the main vessels) have the “futuristic” nature (search). Usage the sex of a patient as a diagnostic character increases the probability of right diagnosis on all congenital heart anomalies by 14%, and on some congenital anomalies—up to 32%. The advantage of character “sex”—stability and simplicity.

Another pathology—congenital hip luxation is four times more frequent in girls, and the left side is the most frequently affected (60%). We shall note that children with this defect can crawl and climb on trees better, than normal children. Anencephaly can be two times more often is found at girls (WHO reports, 1966). Darwin mentioned above permitted standard muscles, which are 1.5 times more often found out in men corpses. He also listed the data on frequency of occurrence newborns with 6-th finger. Here also the number of boys exceeds the number of girls 2 times (Darwin, 1953).

“Epidemiological rule of sex ratio”: Juvenile diseases are more frequent in females and vice versa for adult diseases.

These regularities explain a number of enigmatic phenomena, e.g., differential mortality of sexes, increased proportion of male newborns at the time of high juvenile mortality, distribution pattern of congenital developmental anomalies, such as heart diseases as well as psychological differences between sexes and occupational preferences etc.

References:
Geodakian V. A., Smirnov N. N. (1968). Sexual Dimorphism and Evolution Lower Crustacea “Problemy Evolutsii” Novosibirsk, "Nauka" '''1''' 30-36.
Roginskij Ja.Ja., M.G.Levin (1963) Antropologija (Anthropology). Moskva: Vyssaja Skola.
Harrison G.A., Weiner J.S., Tanner J.M., Barnicot N.A. (1964) Human biology. Oxford: Oxford University Press
.
Witelson S. F. Sex and the single hemisphere. Science, 1976, v. 193, N 4251, p. 425–427.

 

Copyright 2005-2009 S. Geodakyan. All rights reserved.

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