Thursday, March 25, 2010

The wise baboons

I read this fascinating history in a book of Robert Sapolsky (“The trouble with testosterone” 1998. Touchstone, New York) and I have not wanted to allow sharing it here. The history has to do with a species of primate slightly less well-known than our nearby relatives (chimpanzee, gorilla, organgután), the baboon or papión sacred (Papio anubis). The baboons are monkeys of good size that inhabit in wide area of savanna and tropical forest in Africa. They are omnivorous opportunists capable of making use of numerous sources of food, such as fruits, roots, tubers, and of seeds; also they are capable of hunting small preys (occasionally, an antelope baby falls down in his hands). It is anticipated that they obtain approximately a third of the food of the hunting.

The baboons present a notable difference between the sexes. The males are approximately the double of big that the females. Another difference, less apparent but not less important, is the fact of the females they remain all his life in the group where they are born, while the males are transferred to other on having come to the "adolescence". In technical terms, the baboons are matrilocales. This situation (or the inverse one, the females leave the group) is current between the primates. Apparently one of the sexes has to emigrate to avoid the inbreeding. For example, between the gorillas, the male young people is expelled by the domineering male as soon as they give the first sample of sexual ripeness. Nevertheless, between the baboons the process is, somehow, “a volunteer“. On having come at certain age, the young baboons experience an irresistible fascination for other groups of baboons and a good day they leave.

The transference between groups is a particularly delicate period in the life of any male of baboon. They go away, but the new group can take certain time in receiving them and an alone baboon in the savanna is an easy prey. It is known that the mortality during this period increases enormously. Once accepted, the young baboon is in the rock bottom of the social scale. From there it will begin establishing relations, giving pokes (bites) and little by little climbing in his baboon career, what means to compete for status to dog's face, seven days a week. On the other hand, the females inherit straight the status of his mothers and this one is not modified usually, so that they do not turn out to be immersed in this crazy career for climbing and usually establish friendly relations they are other individuals. Between the males, the friendship is an unattainable luxury given the intense rivalry. The baboons male do not have friendly, like very much temporary Allied Forces.

Curiously, the investigators who have studied to this species observed that with enough frequency there take place other transferences of group in which the animal that goes away is a male of advanced age. This turned out to be surprising at first. If the process is dangerous for a young individual, it it is much more for one old. And the future that does not wait for him either is very pleasing: why was going to want a male to begin again when the forces begin him failing?

The answer seems to be in one of the darkest aspects of the nature babuina. It is known that in the social hierarchy of these animals, the interactions take place preferably between individuals of similar status. The male alpha will watch carefully to the number two to prevent from supplanting him, and two it will be careful with what it makes three, and this way successively. Nevertheless, in some cases it was seen that the domineering males had an unexpected number of interactions with individuals of low status. In these cases, the individual of low status was invariably an old male who had occupied years behind a high position in the hierarchy. And the word “interactions“ is an euphemism to say that the domineering males were making the life literally impossible to him. Since it could be waited, the perpetrators of this torture had suffered in his meats the domination of the old male when they were young, and now they were spending invoice to him. If you are a baboon, the savanna is not a country for old men. And so, the question of why do the old men go away turns out to be easy to answer. In another group the things will not go too much good but at least they will be anonymous individuals and they will leave them (relatively in peace). Approximately 50 % of the males ends up by emigrating.

But the most interesting thing comes now. The etóloga Bárbara Smuts thought that between the males who were not emigrating on having aged, some of them had supported a conduct quite different from the prototype of ambitious baboon. These individuals had established years behind friendly relations with other individuals, invariably females. The term “friendship“ can look like an anthropomorphism applied to these primates, but it is defined definitely in terms of the time that two individuals occupy in be delousing mutually, as well as in the mutual help in conflicts with other members or opposite to predators. Even more, these wise baboons had retired it was doing time (or at least, diminished) his emulation for climbing in the hierarchy and this attitude yields his fruits in the old age. The wise baboons are protected from the harassment of the domineering males by his "friends" and by his "reputation" of slightly domineering individuals. There is not doubt that this strategy is beneficial, at individual level, for that they practise it. What is not clear is if it turns out to be beneficial in reproductive terms.

Is there anything in this history that could be applied to our species? Apparently, this way it is. Of completely independent form, the psychologists have studied the differences between sexes with regard to which there is it names in English successful aging. Teresa Seeman and his companions of the University of yale have showed that men and women differ drastically in the quality and number of friendly relations that they support when they come at an advanced age. And this factor seems to be determinant: the symmetrical and reciprocal friendly relations suppose a considerable psychological protection. These results are concordant with many other studies that demonstrate that the women have major capacity (and major tendency) to establish friendly relations and to communicate.

Often this type of studies is misinterpreted. It is very possible that there are innate differences of behavior between men and women (as between baboons and babuinas) but that they are innate it does not mean that they could not change. It means that it will be to work more to change them. Just as the wise baboons, the ambitious human beings have the option to invest more time and I struggle in supporting friendly relations and less in advancing in his careers, to be able to gather the fruits further on.

What these distant cousins are saying to us is that it is worth having a pension plan in the affective area.

Sapolsky, R. (1996) American Journal of Primatology. 39:149-157.

Seeman, T. et to. (1994). Annals of Behavioral Medicine 16:95-.

Smuts, B. (1985) “Sex and friendship in Baboons” Aldine Pub., New York.


Tuesday, March 23, 2010

Biology and social status

CONFERENCE CHATS

ON TUESDAY, DECEMBER 22 21:00

It is clear that the social status, already it is in the shape of money, political power, academic prestige or simple famoseo, it is something that matters very much for the human beings. All the studied societies have some type of hierarchy, although in some cases this one is very lax. It is not surprising that in the species nearest to us also diverse forms of hierarchy exist between individuals. The Biology can explain some things to us on the appearance of this type during the evolutionary process of these hierarchic systems and, perhaps, some thing on the implied molecules. On the other hand, the Biology cannot say to us what things are or are not acceptable in this sense, since this is a question of values and not of facts. Nevertheless, the examination of the phenomenon of the social inequality from the biological point of view, might give us some tracks to handle the thorny matter of the inequality.

conference chats (30minutos) +

PUB SAVOY

C / Meléndez Valdés 28 Meter Quevedo

Madrid 28015, Spain

It notices: the entry costs 5 euros and gives right to 2 consumptions

Punctuality is requested


Saturday, March 20, 2010

The man who was whispering to the hens

If we place a group of hens not 'known' in the same corral, we will observe the following conduct. At first, the animals prove to be often aggressive some with others. Numerous 'fights' take place to pecks, in general slightly bloody. Nevertheless, as the time is happening the fights are less frequent. What is observed is that the hens have established a 'status' that determines exactly the domination order. If she turns out to be eaten, the domineering animal prefers to sting, then it will make it the following one and then the following one up to the last one. Since it is logical, what it determines the status of every individual it is the result of the different confrontations in the initial phase. Of some form, each one 'knows' the possibilities that it has of gaining a fight, what allows to go away straight to the result, saving itself the aggression in strict sense. The realized experiments, in which it was extracted to an animal of the group and one was returning him to introduce after an interval, they indicate that these remember the hierarchy approximately two weeks. It has been proved that if the social order falters artificially, the animals grow more slowly and put less eggs.

This phenomenon, the picoteo order in the hens, was described for the first time in 1922 by the Swedish scientist Thorleif Schjelderup-Ebbe [1]. It turns out to be curious that this conduct was happening unnoticed during the thousands of previous years, in which the human beings and the funks have had a narrow coexistence. It is clear that the behavior of these animals did not cause too much interest until this investigator began his experiments. Apparently, Schjelderup-Ebbe was a real lover of the hens from his most tender infancy, and they tell that his mother made him construct a henhouse in his house so that he could observe them as much as one wants.

The picoteo order has been observed in hundreds of species of birds and mammals. Since the mammals do not peck, the scientists prefer to use the term ‘hierarchy‘ to name the phenomenon, of which numerous forms and variants exist, although the basic idea is the same in all the cases: some animals dominate on others. For example, between the males of common rat (Rattus norvegicus) exist only two classes: the domineering ones and the dominated ones [2]. The first ones, called an alpha, are animals of strong aspect and they usually do not have injuries signs. These males behave of more trusting form, move freely without being bothered and attack the intruders if they penetrate in his territory. The bloody fights are not frequent between males alpha, although yes the positions of threat and any clashes. The males beta move back when they appear the alpha, do not attack the intruders and behave 'friendly' between them.

The hierarchy system existence usually goes accompanied by rules of threat and submission, which constitute real communication codes between animals and the real aggression acts allow to save themselves. The Swiss R. Schenkel [3] studied in the middle of the XXth century the codes of fight of the wolves (Canis lupus). The animals of top status have a position of typical aggression, with the elevated tail and the stiff paws, while the animal grunts and raises the top lip discovering his canine ones. The subordinated animals adopt submission positions bending the ears and going ‘the tail between the legs’. It is not infrequent to observe these behavior rules in the domestic dogs.

[1] Schjeldrup-Ebbe, T. (1922) “Social Beiträge zur Social-psychologie psychologie des Haushuhns” Z Psicol. 88:226 -

[2] Barnett, S.A. “The conduct of the animals and of the man” Publishing Alliance p.192.1972

[3] Schenkel, R. (1947) “Ausdrucks-studien an Wolfen” Behaviour 1:81-129


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Friday, March 19, 2010

Chat - conference on Evolution of the brain

Alberto Ferrús is a teacher of investigation of the Spanish National Research Council (CSIC) in the Institute Cajal. His professional experience includes the cellular and molecular mecanimos of the sensory perception, learning and the memory in experimentation animals. It was rewarded by the Award Demuth granted by International Brain Research Organization. He is a member of the Alliance He damages for the promotion and diffusion of the studies on the brain and usually takes part in science popularization programs. His Résumé: http://www.ferrus-flysynapse.es/pdfs/cvferrusesp.pdf he will speak it to Us about the evolution of the brain and the gradual appearance of cognitive properties, especially the language. In Álvaro's words, which the gathering will moderate:“ I have had the privilege of having listened to him in two conferences, in the Foundation Juan March http://www.march.es/conferencias/anteriores/voz.asp?id=1549, and in the one that it offered in the chair CTR of the ICAI, http://www.upcomillas.es/webcorporativo/Centros/catedras/ctr/Documentos/FERRUSdOCMARCOComillasABRIL2006.pdf. To live in Madrid gives one the opportunity to contact with excellent personages of the science (culture). The closeness and interest showed from the beginning by Alberto Ferrús I consider it to be deserving of sharing it with you and keeping on learning why we are as we are, where from our emotions arise and how we perceive our reality. Finally, a worth, humble one and merecidísimo homage to Charles Darwin
VERY IMPORTANT: To start at 21:00 exactly it is an indispensable requisite that we all have paid to Rali, the barmaid. We ask you as soon as you should come to go to the bar to obtain two tickets that give right to two consumptions. Collaboration is requested

We wait for you at 20:15. The chat will start at 21:00 exactly and we will finish at about 23:00.

OUT OF DEFERENCE AND TO AVOID BAD SMOKES IT IS ASKED TO SMOKE IN THE ROOM OF GATHERINGS

Please: PUNCTUALITY

Place: Savoy Club
Direction: c / Meléndez Valdés, 28
It dates: On Tuesday, the 12th of January 2010
Beginning of the gathering: 21:00
Meters: Quevedo, San Bernardo, Moncloa and Argüelles

http://maps.google.es/maps?hl=es&tab=wl I Boast: 5 € for two consumptions (They have to be emaciated the same day)

Watch Gossip Girl S03E14 The Lady Vanished now

Biochemistry of the status

In the middle of the seventies, McGuire and Raleigh [1] began a fruitful investigation line on the relations between domination and cerebral chemistry. These investigators demonstrated that in a macaque species, the changes in the serotonina level were related to changes in the status of the animal. In a series of fascinating experiments, they thought that if an animal of low status was separating and one was treating him with the medicine Prozac, which raises the serotonina, it is observed that the treated animal was rising from status to having returned to the group, in some cases until alpha to turn into the leader or male. This result is particularly interesting because it indicates us that a biochemical property of the brain can be the result of the interaction with the ambience and, at the same time, the modification of this property into pharmacological methods can change the type of interaction between an individual and the rest. Ambience and brain are a highway of double route.

In these experiments, the domineering macaques were showing a 'moderate' and 'auto-controlled' conduct; on the other hand, the individuals subordinated tended to be startled and his conduct seemed to be governed by external stimuli, more than interns. In these individuals, an emotional outburst was observed and even a tendency to the compulsive aggression against other individuals. The ethologists interpret that in individuals of low status, the low serotonina levels turn out to be beneficial since they inhibit his activity motorboat, allowing them to save energy and avoid confrontations with individuals of high status. The emotional outburst observed in these individuals turns out to be, at first sight, paradoxical; nevertheless, the relation between serotonina fall and aggressive and impulsive conduct has been demonstrated in many species. It is possible that this impulsive tendency in individuals of low status also has an adaptive value. Let's remember that to be to the fund of the scale of domination is a quite bad situation from the reproductive point of view. It is necessary to think that an individual who should be in this situation should face the ‘death darwiniana’, this is after progeny does not stop. In these circumstances, an impetuous conduct, like snatching the meal from an individual of major status, can turn out to be beneficial. Let's not forget that the chronic incapability to control the aggressiveness can determine that an individual loses his integration in the group. In most cases, this has a reproductive cost for the above mentioned individual, but if this one finds close to the 'fund' of the scale his exit of the group it can turn out to be indifferent, or even beneficial in reproductive terms by means of alternative social strategies (such like clandestine copulations or the search of a new group). Sometimes, a desperate situation needs a desperate solution.

[1] Raleigh, M.J., McGuire, M.T., Brammer, G.L., Pollack, D.B., and Yuwiler, A. (1991) “Setoninergic mechanisms promote dominance acquisition in adult male vervet monkeys” Brain Res. 559:181-190


Thursday, March 18, 2010

Separate of the power the addicts to the power

In 1997, one sudden one (although not too virulent) meningitis epidemic in the Community of Madrid caused considerable alarm between the parents with children in school age. The sanitary authorities were not in that moment partial to the massive vaccination of the whole school population, although later they changed opinion (these decisions are difficult to take and the information at the moment of never taking them is finished). The case is that, in the middle of this fuss, the citizens of on foot we find out that the President of that time of the Congress of the Deputies (Federico Trillo) had used the official car and the official doctor of the Congress to vaccinate his children.

I suppose that he should not scandalize me for something like that. Obviously, the anecdote reflects the moral tasting of the personage, but worse things we have seen in the same personage and in others (of the same one and of other parties). The tireless double mulberry tree of many politicians is a topic appellant in the heads of the newspapers. Beyond the rejection, the curiosity assaults me for the underlying psychological mechanism: Is it a question of simple hard face or really they believe that his acts are ruled by a rasero different from that of the rest of the population? It makes me happy to see that this question has attracted the attention of the professional scientists … and the answer (judging by a limited number of studies) is that, really, the power corrupts, but only to those that are thinking about deserving it.

The study (here), published by Joris Lammers (University of Tillburg) and collaborators, explores this question for the method of inducing (priming) a sensation of being able in the subjects of the study, for example asking them to remember a situation like that, later to evaluate his moral behavior in certain situations. For example, in a study the "priming" was realized in two random groups, one high power and other of down. Later each of the groups split into other two. Him one spent to one of them a questionnaire in which they were evaluating until they were considering point to be immoral to "inflate" the expenses in a work trip; another group took part in a game of dice, in which the punctuation that they were extracting could turn into a small award in cash (the dice tiraben in a private cubicle and the subject he was communicating the result to the experimenter).

In case of the questionnaire, the group of the powerful ones valued worse that that of the helpless ones doing pitfalls in the accounts, but - and this is the interesting thing - the same persons did more pitfall than another group on having brought (in his favor) the result of the dice. In other words, the mere allusion to a situation to be able was doing the persons most inclined to do pitfalls and to censure the foreign pitfalls.

Another similar study, nevertheless, suggests that this tendency to behave of hypocritical form does not happen in all the cases, but in those individuals that they think that they have acquired "according to the law" such power. Curiously, the individuals who were thinking that “it was not deserved”, were tending to be more demanding with it itself as with other persons. Instead of of acting hypocritically they were doing it hipércritamente (the swearword belongs to the authors).

I know that such a thing is impossible, but: would there be any way of achieving that there were gaining access to power positions persons who really do not want to exercise it and agree for felt cigar of the duty?


Wednesday, March 17, 2010

The explosion of 10.000 years ago

The times must be changing, because a few years ago this book had untied a criticism hurricane and, nevertheless, it has happened relatively unnoticed (or at least a too big candle has not been mounted) the reason? His authors, Cochran and Harpending, open one of the most awesome "melons" of the Biology / psychology, that of the (supposed) cognitive differences between ethnic groups.

But let's start for the beginning. The fundamental thesis of the book is that the human evolution has not stopped in the last milleniums, but on the contrary, it has hastened with the arrival of the civilization and the progress. The authors support that the new living conditions created by the development of the agriculture - first - and for the creation of the states - later - new selective pressures created in the human populations. This idea is not, in itself, himself; what is difficult is to present solid experimental evidence that endorses it. Undoubtedly, the authors do an effort to argue well his thesis although, in my opinion, these are at the moment a hypothesis which empirical assertion stays enough background. It is necessary to admit also that the authors are honored enough in this sense: they say clearly when they are speculating and when his affirmations are well sustained.

Essentially, Cochran and Harpending throw three (risky) ideas to the forum. The first one is that the human beings modern (cro-magnon) that replaced in Europe the neanderthales should have acquired of these some alelos by means of a well-known process like introgresión. The above mentioned genes would have allowed to the cro-magnones to adapt themselves to the hard European conditions during the last glaciation. The idea is not ludicrous. For example, it has been seen that the color of the hair of the wolves of Alaska and Canada owes up to a point to a phenomenon of introgresión (more info). Nevertheless, the genetic information obtained until now shows that cro-magnones and neanderthales they remained genetically separated. It is possible that into the future new information changes the panorama, but in this moment this evidence is nonexistent (see).

The second hypothesis has to do with the appearance of the tolerance to lactose in our species. This topic has been treated other times in this blog (here). The authors go a little further and affirm that the appearance of this mutation that allows to the adults to consume milk, constituted a determinant advantage for the Indo-European peoples up to the point of being the cause of that the Indo-European migration took place. Again, it is possible that it has been like that but the information on which the hypothesis is based is still insufficient.

Finally, we go away to the most controversial hypothesis of all: according to the authors, the Jews ashkenazi turned out to be forced to devote themselves to professions related to the banking and the finance of almost exclusive form during the Middle Age; due to this selective pressure, the ashkenazi would be more intelligent than other ethnic groups. The authors use the number of Nobel Prizes obtained by individuals with this ancestry in the last century.

This type of controversies always supposes a streak species in the sand: it is necessary to be against or in favor. So I am going to define myself: I refuse to accept streaks in the sand. On the one hand, I believe that the arguments used by the authors are insufficient (although they present his case of convincing form). It would be necessary to find alelos clearly tied to the intelligence (understood like IQ, what has a clear limitation) and then to demonstrate that in certain ethnic groups the above mentioned alelos are more frequent than in others. To today, the information is not conclusive not much less.

On the other hand, it seems possible to me that a hypothesis of this type goes so far as to be hard supported by the information some (perhaps there are no populations genetically taller than others?). When that happens, I am ready to allow me to convince, because I believe that the science is much more important and less harmful long-term that the political correction (more on this).

But this day has not come.

PS. On the evolution of the human species at present we will speak another day


The last tormentors

During the Middle Age, the spectacles in which animals were tortured were very frequent in the whole Europe: dogs' fights, roosters, rats and, of course, bullfights. In England the calls were very popular bull-baitings in those who were tortured to the bulls with the dogs' help especially trained. Also there was bear-baitings, although the bears were much more scarce and difficult to support. Naturally, there were other times. The public executions and the Edicts of Fé were constituting a very valued popular entertainment. The last public execution in Madrid took place in 1890.

From the XVIIIth century the ideas of the philosophers of the Enlightenment were drawing little by little into the society, and this type of acts begun being considered to be brutal and unacceptable. In England they were abolished in the XIXth century, so that the debate that is beginning taking place these days in Spain on the abolition of the bullfights is late of more than one century with regard to the rest of Europe. The only reason that makes us special to the Spanish is that we are the only ones that we allow the torture of an animal to be a public spectacle. Two hundred years ago it was doing the whole world.

It is clear that the "tradition" cannot be invoked like a sufficient argument in itself to defend the savagery that the bullfights suppose: Perhaps the feminine ablation is not traditional in many African countries? Or in "sati", this Hindu habit of burning the widow in the pyre of the husband? Of course, the gladiators' fights would have been considered to be a part of the Hispanic-Roman “tradition”. Although it it does not seem, the world has evolved enough in the moral sense, for which it has been necessary to break with diverse "traditions". The affirmation of which “the bulls are a culture” it plays with the important double of the word. On the one hand, any thing that should happen often in a society can be considered to be a part of his culture. On the other hand, the term has a positive connotation of “activities of top order that ennoblecen to those who practise them” like the art, the literature or the science. If it is accepted that “the bulls are a culture” we might apply the same argument to the violence male chauvinist, and: who is going to deny that the machismo has a long tradition in Spain?

Pro-bullfighting some of them argue that he has no sense to prohibit the bullfights if not prohíben also the slaughters of seals or the hunting in general. The argument comes to admit that yes, that the bullfights are a drove of donkeys but also there are other droves of donkeys. For the same ones, if they accuse someone of a crime it might defend itself saying that …: Hitler committed more crimes! And it is very possible that also should prohibit themselves other atrocities. But this is a completely different matter.

The possible extinction of the bull of fight is other of the arguments commonly personnel to defend the bullfighting platform, although it is not a valid argument either. The fight bull is a race of a domestic species (Bos taurus) and naturally, the circulation depends on the decisions that the human beings take on this matter. His extinction, if the bullfights were prohibited would not be inevitable (although the conservation would have a cost). The case would remain included in the general problems of preserving the biodiversity of animals and domestic plants that fall down in desuetude. A problem undoubtedly urgent and that it affects to species as emblematic as the donkey. Similarly, the pastures dedicated to the brave cattle would not have why to turn to the moment into urban developments or shopping centers. They should be protected due to the wealth of these ecosystems, but undoubtedly, other forms of use, respectful with the way are possible.

Some pro-bullfighting radicals have gone so far as to argue that the bulls do not suffer, although the violence and cruelty of the "holiday" is clear. Neurological reasons exist to think that yes they do it. To start, his system límbico is very similar to ours. To continue, the pain has a strong adaptive value in the top animals. Curiously, there does not appear any research work published on this topic in PubMed, the principal database of biomedical investigations. Search in PubMed (here)

In short, the bullfights do a spectacle of the torture of an animal capable of suffering and there are therefore a double "savagery", for the torture in themselves and for the fact of doing a public spectacle of it and (often) televised. On having raised it to the category of Good of Cultural Interest, our leaders have given one more step in the “apology of the torture”, stealing also a public debate that should happen promptly.

Two hundred years ago the whole world in Europe was doing these things. Now only we make them the Spanish. We are the last tormentors. A doubtful honor.

More info:

“Live through the animals!” J. Mosterín. 1998. Publishing house Debates. Madrid.

“Animal Liberation” P. Singer. 1975. Ed. Harper Collins. New York.

“Animals and why they matter” M. Midgley. 1983. University of Georgia Press. Athens, US.


Tuesday, March 16, 2010

Genetic diversity and sexual success

In the mammals it departs from our aptitude to fight infections it is tied to a group of genes of the Biggest so called Antigen of Histocompatibilidad, whose initials in English are MHC. These constitute a complex group of different genes involved in the regulation of the immune answer and present an enormous polymorphism grade, that is to say, in the populations numerous alelos exist for every gene. For example, in the mouse it usually has of the order of 100 alelos different, therefore the highest number of possible combinations exists. The proteins codified by these genes fulfill an important role in the recognition of strange proteins on the part of a particular type of immune cells, the lymphocytes T. Therefore, the differences between the MHC of different individuals collaborate to the aptitude to recognize and to answer before different pathogenic, so that the "quantity" of present genetic changeability in the MHCs of an individual is related to his aptitude to fight infections. Simplifying very much, individuals with high changeability would possess “better genes” (in this aspect) than individuals with less changeability.

Also, the changeability of the MHC plays a role in the determination of the corporal smell of every individual, because they affect to the production of soluble proteins capable of joining volatile substances, and for it responsible for the smell. These proteins affect to the type of bacterium that can grow in the skin, what also has an indirect effect in the corporal smell as what they can be perceived by the potential couples. Therefore, it is reasonable to think that the individuals with tall variablidad in his MHCs might turn out to be more attractions as couples.

To prove this hypothesis, Hanne Lie and his collaborators of the University of Western Australia analyzed the genetic diversity in good number of volunteers (university students, as it is usually habitual), to whom also they spent a questionnaire about his sexual customs and his success in these matters. After some variables fitted (like the attitude opposite to the sex and the age of the first relation) the investigators thought that the diversity of the MHC was positively related to the sexual partners frequency. This effect was not observed by the genetic changeability in general, what he suggests that this character could have been an object of sexual selection in our species. Curiously, the effect was not also observed in the boys, without an apparent explanation existing for it.

The truth is that squedan many questions without constestar: how do the potential couples perceive the changeability of the MHC? Possibly, across the smell, but that also is necessary to demonstrate it: Does this phenomenon have an adaptive value? It is possible, but neither is an irrefutable test. In other articles it has been seen that the individuals, in many mammals species (included the human beings), tend to pair with individuals with alelos MHCs different from the proper ones; which is a different question, although also it has as a result a descent with major changeability in the above mentioned genes: are both phenomena compatible? In any case, it must be born in mind that the MHC does not constitute the only one (not vaguely the most important) “criterion of matching” in human beings.

M.I.S.N. (More Investigation will Be Necessary)

The work here