Sexuality (reproduction)

The Sexualité is in biology a function of reproduction of the living beings

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Reproduction

Sexuality is the fact of the reproduction, which one can translate by the " mélange" of two individuals to obtain an always single third from it, by what genetically different from all the others.

sexuality can thus be also defined in opposition to the asexual Multiplication, which allows a " parent" to only multiply. Either with identical by the vegetative Multiplication (which thus generates Clone S), or by the Parthénogenèse the spontaneous development of not fertilized ovules (observable in the bees for example).

The sexuée reproduction corresponds to an alternation of two phases, a diploïde, haploid, separated by the meiosis and fecundation:

Haploidy - > fecundation - > Diploïdie - > Meiosis - > Haploidy (and so on)

haploid means that the cells concerned have a specimen of each chromosome

diploïde means that the cells concerned have two specimen of each chromosome, i.e. for each gene coding a precise character, there exist two versions called allele.

The meiosis is one moment of mixing will intra and inter chromosomal, which allows the haploid cells to be all different from/to each other.

fecundation makes it possible to assemble two randomly gamètes (haploid) meetings and competition to give rise to a new individual genetic inheritance " nouveau".

it is thanks to all these cumulated chances that reproduction sexué car its advantage: The unicity of each individual of a species. What makes it possible to face the natural selection.

The sex

Always according to the biological bases, sexuality is associated with a differentiation of the individuals into two Sexe S (sometimes more at certain species), generally the male and the Femelle, which can in certain cases (at the Escargot in particular) coexist at same individuals: they are Hermaphrodites.

This distinction of the kind S is genetic. For the mankind for example, it is the association of the sexual chomosomes X and Y which is determining. (Male XY, , and XX female).

The role of sexuality

The species

What characterizes the vegetable Monde in general alive and it is that each species, of the organization Unicellulaire with the advanced Vertébré S behaves in such way that it expresses what can seem a will to survive as a species , whereas the individuals are individually brought to disappear.

Whereas the unicellular organizations reproduce by fission with a level of very restricted genetic exchange, one can speak about sexuality only at the organizations Pluricellulaire S because it is with them that part of the cells specializes while being directed towards the reproduction. This specialization increases considerably the level of the exchanges between the individuals and thus the possibilities of evolution or change by the mixing of the genetic material resulting from these exchanges.

As one progresses on the scale of the alive world, it seems to appear what one could call individuals a increasingly large freedom of choice . Indeed, at the simplest organizations of the alive world, the sexual exchanges seem subjected to a programming which leave only very little place to the individual behaviors whereas at the most advanced Mammifère S, of the possibilities of larger initiatives seem to give the opportunity to him to escape the Déterminisme partly.

With the Man, of which the cerebral capacities allowed him to work out the dimension of the Symbolique and its correlation, the Imaginaire, the share of the determinism seems even more restricted. But it would be undoubtedly an error to think that it completely disappeared and certain " interrogations; naïves" on what pushes the Man to be reproduced in a so hostile world, would make well take into account this share of our biological heritage.

Reproduction and programming

The ethologic studies show that the reproduction of the Insecte S, the Poisson S and the Oiseau X seems to be brought back to an exchange of Stimulus - reaction. This means in practice that the individuals in a given species exchange signals coded and programmed for each species. The signals employed by each species are founded on colors, postures, movements of certain parts of the body. This is in experiments verifiable using lures which can be reduced, for example for certain birds, with a silhouette which, presented in the good orientation, will start an appropriate response, marking the acceptance of the sex act.

It is a impregnation which takes place as of the first days of the existence of these animals. Konrad Lorenz thus could show that certain birds deprived as of the blossoming of their mother and raised by the human ones, answered by typical postures of acceptance of the copulation when certain movements of the hand were produced by the experimenter. It is not a question then, for these animal species, of a meeting between individuals, with the direction where the other would be perceived as such, but simply development of an adapted program started by a specific signal.

This explains us why Lorenz can affirm that: The formation of an instinctive act resembles a body. ( On the formation of the concept of instinct ). One can say it differently: the instinct for a given species is a program which develops when certain conditions are filled.

At the mammalian inferiors the copulation is still dependant in a narrow way of an exchange of signals innate or learned, even if those are varied and in particular make enter a orielle dimension direction.

But at the anthropoïde S , it seems well that one reaches again something which allows a certain access to the individuation. The documentary animalists accustomed us to look at and recognize some erotism in the higher monkeys: ceremony of the mutual delousing, plays oral, social plays in any kind. There is the starter of a taking into account of the individual, a meeting which can seem to us an outline compared to our human behaviors, but which translates a true qualitative jump.

Sexuality in the mammals

In the higher mammals, which appears particularly striking it is the larger complexity of the sexual phenomenon which reveals the coexistence of two great characteristics:

the periodicity which seems a general rule of the animal world. The Primate S, like the very great majority of the animal species, are coupled only at periods given of the year. It was established that these periods are conditioned by climatic factors, like the temperature variations, the luminosity which stimulate the Hypothalamus which in its turn gives a signal to the Hypophyse to engage the training cycle of the Gonade S. This remains true at the monkeys and the anthropoïdes, for which the female is attracting sexually only at certain periods of the year.
the social dimension which remains a characteristic of the monkeys and anthropoïdes. Experiments of asocialisation were undertaken near certain monkeys: they are isolated, deprived from the social relations which they would have maintained with their congeneric for the period their development. Become ripe sexual and put in presence from/to each other, it appears that they miss something of essence which supports the sexual meeting. The males behave as if they did not know how to practice intromission; the female on its side does not take the adequate posture. The behavior of these subjects translates a disorder to which they cannot give the appropriate response.

Much more, the rare couples which arrive at the coitus comprise then in a completely unusual way when the female put its small low. It is not occupied any, is shown rejecting and does not manage to lay down the social rules who are those of his species.

Apart from any experimentation, the observation of Babouin S in freedom showed that the young males which became sexual ripe at the five years age cannot reach the coitus before the age of ten or eleven years, i.e. at one time when they acquired a sufficient social status in their social group. Between five and ten or eleven years, not only they are seen discouraged in their attempts by the other dominant males, but the females push back them.

All these elements show that the sexuality of the monkeys is not only dependant on physiological maturation: the young monkeys learn by socialization, their maturation depends on the early exercise of the rules of socialization of their group.

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