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Bad guy DNA


In evolution, everything is quite simple and cynical. If some genes increase the probability of leaving many offspring, then they will spread with each generation in the population more and more widely. If genes, on the contrary, reduce the likelihood of successful reproduction, then over time they will occur less and less. This principle concerns not only banal anatomy and physiology, but also behavior. We make any decisions by the brain, it consists of cells, the cells - of molecules, the composition of molecules is determined by genes. If some genes increase the likelihood of making a decision useful for the survival of the offspring, then their carrier will have more children who inherit the same valuable genes will also behave correctly, and so on.
The good news is that in the case of reproduction, there is no one right answer. If a man has genes that increase his desire for casual relationships, then this is certainly good - perhaps some of the seduced women will give birth to children from him. But if a man instead has genes that increase the likelihood of developing a strong attachment to his only woman, as well as a tendency to care for children born, then this may be even better because in such a situation the emergence of children and their continued survival is much easier to control. If a heartbreaker is very lucky with beauty, wealth, charm and independent mistresses, he may have ten children. But, if he is lucky a little less, he can not leave a single one. But a caring family man, with minimal effort, will find a woman willing to give birth to four of them, and at the same time all four will live to adulthood and be successful and prosperous, because two parents took good care of them.
All animals somehow balance between these strategies. The most convenient object to search for molecular mechanisms that increase or decrease the tendency of males to monogamy is again voles. I have already mentioned that the females of the steppe voles tend to become attached to a partner, although sometimes they change it. So, in this species there is complete equality: the males also spend a lot of time with their wives and children and take care of them. But in most genetically related species, for example, in meadow or mountain voles, nothing like this happens: males and females are found only for sex. Male does not show any interest to posterity, and females in general pay less attention to their children than in successful full families of steppe voles.
In the laboratory, love from voles is studied as follows: a young male virgin is placed in a cage for 24 hours together with the same young and inexperienced female. As a rule, six hours after they get to know each other are enough for the rodents to like each other, and they spend the rest of the day having sex (not continuously, but often). To then check whether the male has become attached to his partner, he is placed in a cage connected to two others: in one his first beloved lives, in the other - an unfamiliar female. The movements of the male are videotaped and calculate how much time he spent in each room. It turns out that experimenters have many ways to influence the emotional preferences of the male.
The most important role in the formation of attachment in males of the steppe vole is the release of dopamine in the nucleus accumbens. There are drugs that block dopamine receptors, such as the famous haloperidol, which has been used in psychiatric clinics for many years to soothe riot patients. So, if before the date the male of the steppe vole is given an injection of haloperidol, then he will mate with the female, but he will not have any attachment 11. No dopamine - no love, sorry. But if, on the contrary, before acquaintance with a female, to introduce an animal apomorphine, which increases the activity of dopamine receptors, attachment will arise even if there was no sex in six hours of contact.
Such experiments Brandon Aragon and Thomas Curtis, employees of the University of Florida, conducted in 2003. In their later works, it turned out that in fact the picture is even more complicated. At least two types of dopamine receptors, D1 and D2, are involved in the formation of attachment, and D2 stimulation causes attachment to the partner, and D1 is responsible for the other side of the coin - lack of interest (or even aggression) to other females. After the first meeting of the male monogamous vole with his future wife, he develops sympathy for her (that is, activation of the D2 receptors), and during the first weeks of living together in the male's brain, the activity of the D1 receptors gradually increases, and he loses all interest in other potential partners . Polygamic voles are not capable of such subtle feelings, because they initially had a different distribution of dopamine receptors in the brain.
While researchers from Florida continue to tinker with dopamine - make brain slices, select pharmacological drugs and introduce new females to monogamous and polygamous males, - Larry Young from Emory University came from the other side and already learned to turn polygamous meadow voles into devoted husbands with the help of gene therapy .
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Bad guy DNA

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