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Why men? Attempts scientific justification



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 Why men? Attempts scientific justification Some time ago, much to his surprise, discovered that one of the most popular queries in search engines is a request \"Why men?\" . Frankly, if I am a little discouraged this circumstance, and putting the question itself seemed absurd.

Meanwhile, it appears that the subject is concerned not only the authors of another no less popular in RuNet query "Why am I so stupid?", But also scientists who believe that males are costly for any biological population, as the rejection of them gives an immediate and a very significant gain in speed of reproduction.

Based on precise mathematical calculations, biologists have concluded that asexual reproduction (or self-fertilization) in exactly two times more effective than the cross with males. Science knows examples where the process of evolution some species of plants and animals moved to asexual reproduction.

Even in 1957 it was found that the rock lizards successfully lay eggs and output offspring. Recently, zoologists have reported an astonishing discovery: two single females rare in the world Komodo dragon zoo UK eggs, from which the light appeared normal calves. And in both cases from unfertilized eggs hatched exclusively males.

To date, approximately 70 known species of bisexual fish, amphibians and reptiles, females are able to independently produce offspring independently of males.

Fuel to the fire of scientific disputes poured findings, claimed that the male Y-chromosome to evolve rapidly diminishes in size. In academic circles, even talking about the evolutionary biological "extinction" and the decline of the male part of humanity. At the same time the calculations were carried out, which shocked the scientific world. According to them, which appeared 300 million years ago, the Y-chromosome in the continuing dynamics of its "shrinkage" should be fully "unravel" in 125 thousand years. After this period, science predicted the disappearance of the last man.

After analyzing the "biological advantage" of such populations, scientists have been puzzled about why the same objective evolutionary progress so far has not led to the dominance of asexual populations of self-fertilizing hermaphrodites, and the extinction of those who propagated the "usual" way, ie with the participation of males.

In particular, the above-mentioned female lizards appear only during sexual reproduction, whereas single females are born exclusively males. Consequently, researchers have hypothesized that this strategy of reproduction does not mean uselessness of gay males and the preference of reproduction, and makes sense only when the animal population is sparse or very small. Why do females give birth to males, which are designed to compensate for the shortfall of fathers?

As a working hypothesis was put forward that bezsamtsovy method of propagation is not considered nature as a more optimal, but is merely a mechanism of survival of the species, due to which a lone female, not having met at an appropriate time, the male is able to sustain their kin.

Still, scientists are scratching their heads: why still need "men"? Indeed, in this case, following the objective laws of evolution, cross-fertilization should produce some benefits, so significant that they cover even double the gain in efficiency of reproduction in case of failure of the males.

So biologists Oregon State University conducted an interesting series of experiments, which gave practical arguments to answer the question about the benefits of cross-breeding.

The experiments were conducted on round worms, which seemed specifically designed for experimental verification of the above hypotheses. These worms are no females, and the population consists of males and hermaphrodites. The latter can reproduce without outside assistance through self-fertilization, generating extremely hermaphrodites.

Males produce sperm that fertilize hermaphrodites. Under cross-fertilization is hermaphrodite progeny of half and half - males.

In the end, as the website of the elements of great science, the experiment proved that sex (cross) breeding has a number of substantive benefits:

 Во-первых, если у бесполого организма возникает вредная мутация His descendants can no longer get rid of it. It will, as a generic curse, passed all his descendants forever. Therefore, in a series of generations of asexual organisms can occur steady accumulation of harmful mutations. In sexual reproduction gene mutation failed to be discarded and replaced with "good" the other parent. As a result, sexual reproduction promotes cleansing of the "genetic load" that is helping to get rid of harmful mutations, avoiding degeneracy.

  Secondly , Sexual reproduction helps the body better adapt to changing conditions due to accelerated accumulation of mutations that are useful in this situation. For example, if one individual has one useful mutation, the other - different. If these organisms are asexual, they have virtually no chance to wait for the unification of the two mutations in a single genome. Cross-fertilization is actually doing all the useful mutations are "common heritage". As a result, the rate of adaptation to changing conditions in organisms with sexual reproduction above.

In general, the benefits of heterosexual species have been scientifically verified. But as they say, not far from it. Not all points above the "e" have been placed, because cross-fertilization occurs not only in dioecious organism. For example, many invertebrates are hermaphrodites, fertilizing is not ourselves, and each other - to cross.

Distributed cross-pollination bisexual (hermaphrodite) animals and plants.

In other words, experimental verification has not shown that "cross-hermaphroditism" in some way inferior dioecious. But for the first of these two options do not have to pay the notorious "double the price." Consequently, the problem still remains ...

Now scientists suggest that the key to solving this puzzle, most likely, is sexual selection, as dioecious allows females meticulously choose their partners, which serves as an additional way to increase the effectiveness of culling and harmful accumulation of useful mutations.

Perhaps this hypothesis is ever receive experimental confirmation. Meanwhile, recent studies of another group of scientists from the Massachusetts Institute of Technology found that Y-chromosome is not a relict material, but rather defines and directs the path of genetic development. Experts have concluded that it was thanks to 11,111,112. male 11,111,113. , Mankind has been able to rapid biological evolution, adapting to changing environmental and social conditions.

 
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