Evolutionary Theory of Sex (ETS)
The Evolutionary Theory of [...] (ETS) suggests an explanation to the [...] dimorphism puzzle. This puzzle compares three types of reproduction known in biology An asexual process is much more efficient and simple as there is no need for mating behavior. Since the offspring of each asexual individual is a clone with the same genotype, the chances of beneficial (most adaptive) configurations for survival are much better than in [...] reproduction. Hermaphroditic organisms are capable of changing their [...] and so each such individual can mate with all other individuals except itself. Hermaphrodite reproduction gives the highest diversity of configurations and an easier mating process than bi-[...] reproduction (such as in humans, when half of the members (males) can’t reproduce and can only diversify the genes). Since in bi-[...] reproduction members of species can mate only with the opposite [...], there are fewer opportunities for mating and a lower diversity of outcome of their gene recombinations, in comparison to hermaphrodites. Meanwhile, bisexual species still have to share food and other resources with members who don’t reproduce (males). In spite of these disadvantages of bi-[...] reproduction, paradoxically, most plants and animals shifted from hermaphroditism and gonochorism to [...] dimorphism. Why? (Figure 1).
In order to explain this paradox, the ETS has two main hypotheses that complement each other: the Principle of Conjugated Subsystems and the Theory of Asynchronous Evolution.
The Principle of Conjugated Subsystems
The first hypothesis suggests that [...] dimorphism gives a species the benefit of having two functional partitions, or subsystems. The male [...] is considered an operative, variation subsystem, while the female [...]—a conservative one. [...] differentiation allows a species to use the male partition to try out various genetic changes, including parasitic and cooperative co-existence for possible inter-species co-evolution and expansion of ecological niches. In Geodakyan terms, species use males as “experimental animals of evolution” and use another partition (female) to maintain the features of the species that were proven to be beneficial. If, during trial-and-error exploration, a species "experiments” with only a part, rather than with the whole population, then another part of the species can continue preserving beneficial characteristics. The ETS explains the links between the emergence of the male [...] and improvement of defenses against pathogens by an evolutionary role for the male partition as an immunology lab: if a new genetic combination is so resilient to harmful factors that even phenotypes with a higher susceptibility to diseases can survive, this combination should be used by the whole species. Thus, to be more specific, the ETS supports the idea that the emergence of [...] facilitated the fight against pathogens (among other inter-species interactions, such as cooperation between species). The ETS, however, does not support the idea that the fight against pathogens was the main function of [...] differentiation. Instead it considers the development of a bi-partition system of [...] reproduction as a systemic feature of advanced species. A series of mechanisms were developed during different stages of [...] evolution to provide this specialization. Compared to females, males have a higher birth rate but also higher mortality, experience more mutations, inherit fewer properties of their parents, have narrower reaction norm (Figure 2), higher aggressiveness, riskier behavior and other properties that can expand ecological niches of their species. Since Darwin it has been noticed that within one species, and among related species, males often differ from each other to a higher degree than females creating a wider distribution of phenotypes. A wider distribution of male phenotypes (high male variability) means an overrepresentation of males at the extremes of the phenotypic distribution, i.e. that there are more males on both tails of the distribution (for example with respect to intelligence, more mentally challenged and more geniuses) than females. The phenomenon of greater male variability was found in primates and humans with respect to physical characteristics, intelligence, personality traits, temperament traits, in semantic perception, physical aggression and other psychological characteristics. This phenomenon coincides with the common understanding that male [...] (i.e. [...] differentiation) emerged and was used by species in mostly variable environments. Computer simulations indeed showed that variability and unpredictable behaviour by a part of a group optimize results for the whole group
Males in many species have great superfluity of gametes, small size and high mobility of gametes, greater mobility of growing male phenotypes, and an inclination towards polygamy. For example, human males have higher susceptibility to all “new” diseases of our century (infarction, arteriosclerosis, cancer, schizophrenia and others). Hamilton (1948) reviewed differential gender death rate for 70 species, including such various forms of a life, as nematodes, mollusks, crustaceans, insects, arachnoidea, birds, reptiles, fishes and mammals. According to these data, for 62 species (89%), the average life of males is shorter than females; for the majority of the remaining 11% there is no difference, and only on rare occasion do males live longer, than females. As the mortality of males increases, their birth-rate (secondary [...] ratio) is also increasing via the negative feedback.
The Theory of Asynchronous Evolution
The second hypothesis, the Theory of Asynchronous Evolution, describes a phylogenetic “distance” between the sexes. According to this hypothesis, genetic changes appear asynchronically in genes in the two sexes. At the initial, divergent phase, evolutionary changes in a trait emerge primarily in males, as in a testing partition of the species. In subsequent generations the trait evolves in both sexes. A similar theory was described later by other authors
History and predictions of the ETS
The ETS was proposed in 1965-85 by Vigen A. Geodakian. He conducted an analysis of [...] ratios, of dispersion patterns, [...] dimorphism in different mutation levels, phenotypic and genotypic diversity of two sexes, feedback control of [...] ratios, rates of birth, rates of mortality, and, susceptibility to new diseases (Geodakyan, 1985, 1999, 2012) .
Wider reaction norm of females was theoretically predicted in 1973 [...] differences in anthropological characteristics of humans were found to be in line with the ETS
Moreover, if the hypothesis is valid, the differences between monozygotic female twins must be greater than between the male ones. At the same time in dizygotic twins like in common siblings, everything must be vice versa. Two studies conducted on 44 monozygotic pairs and 53 monozygotic and 38 dizygotic pairs of twins confirmed the predictions.
The hypothesis was published in more than 150 scientific publications (but mostly in Russian), covering different aspects of [...] related questions—longevity, differentiation of brain and hands, [...] chromosomes, mechanisms of [...] ratio regulation, heart diseases and other illnesses Two conferences in Russia were devoted exclusively to this theory (Saint Petersburg, Russia, 1990, 1992). The theory was included in the textbooks, college study programs, was covered in numerous newspaper and magazine articles and TV programs.
Upgrade of the ETS
Trofimova reviewed the most consistent psychological and behavioural [...] differences and linked them to the ETS. She suggested a pattern of consistent [...] differences in physical, verbal and social dis/abilities corresponding to the idea of the ETS considering [...] dimorphism as a functional specialization of a species into two partitions (1) conservational, and (2) variational. In females, superiority in verbal abilities, rule obedience, socialisation, empathy and agreeableness was presented as a reflection of the systemic conservational function of the female [...]. Male superiority in risk- and sensation seeking, physical abilities, higher rates in psychopathy, dyslexia, autism, schizophrenia, higher birth and accidental death rates was a reflection of the systemic variational function (testing the boundaries of beneficial characteristics) of the male [...]. Such links suggested that the directionality of [...] selection and the division of labour between sexes were the consequence and the mechanisms, and not the cause, of the [...] differences in human behavioural dis/abilities. As a result, psychological [...] differences might be influenced by a global tendency within a species to expand its norm of reaction, but at the same time to preserve the beneficial properties of the species.
Moreover, Trofimova suggested a “redundancy pruning” hypothesis as an upgrade of ETS theory. She pointed out that the variational function of the “male partition” might also provide irrelevance/redundancy pruning of an excess in a bank of beneficial characteristics of a species, in spite of resistance from the norm-driven conservational partition of species. This might explain contradictory [...] differences, allocating a high drive for social status/power in the [...] with the least abilities for social interaction. The higher the rates of communicative disorders and psychopathy in males, the easier it is for them to disengage from normative expectations and to act under social disapproval.