Caesarean section is used, if the doctors are expecting or already have a difficult birth: for example, when the baby cannot pass through birth canal – the mother’s pelvis is too narrow. Not long ago, scientists analyzed the statistics of these genera, discovered an amazing feature – it is now actively practiced by caesarean section now affects human evolution. But about all under the order.
Some not-yet-born babies are gaining too much weight in the womb of a woman. As a result, their stature does not allow them to pass through the pelvis of the mother. Because of this, the child may die during childbirth or harm the body of the expectant mother. Here before the doctors, a kind of “obstetric dilemma.” On the one hand, a large children have more chances to survive in childhood. On the other, it is believed that children born to light not in a natural way, and during cesarean section, can have serious health problems.
But, like most of the features of human anatomy, size newborn and width of the pelvis of the mother are very diverse. The same applies to ease passage of the baby through the birth canal and pelvis. And always will be some part of newborn children who for certain reasons will not freely pass through the birth canal. However, due to the caesarean section, such children (and the bearing of their women) don’t die.
This affects the evolution of the human race. Some of our readers will arise a reasonable question: how evolution can happen so fast, isn’t this is a whole Millennium? Because this procedure became widely used only in the 1950-ies. Experts say that evolution may occur in the lifetime of just one generation, for example, drastic ecological changes.
an Example might be: on the island there is a dangerous disease that kills almost all animal species, but leaves alive those who have innate immunity was stronger than the disease. In this case, evolution will occur in one generation (survive only those who were able to escape, and they will give a new strong offspring). In the case of caesarean section since the beginning of the wide application of the procedure appeared in the world have two or even three human generations a “new breed”.
And, according to scientists, the regular use of cesarean delivery is already affecting human evolution. Today more and more mothers because of the narrow pelvis and need surgery during childbirth. According to experts, when the child is unable to freely pass through the birth canal, increased from 30 per 1000 cases in the 1960-ies to 36 per 1000 cases for today’s years.
Historically, certain genes are not passed on from mother to child because both could die during childbirth.
“Women with a very narrow pelvis even 100 years ago, not survived at birth. Now this does not happen, this means that they pass on their genes to the narrow pelvis to their daughters,” says Philip Mitterecker (Philipp Mitteroecker) from the University of Vienna.
He believes that here lies the long-standing question in the understanding of human evolution. “Why the frequency of problems with the birth so high? In particular, we are talking about the so-called disproportion between head and pelvis – that is, when the baby cannot pass through birth canal of the mother” — says the scientist.
According to him, without proper medical intervention such pregnancies often end in death. “And this from the point of view of evolution looks like a selection,” says Mitterecker.
Here, many specialists are asking other long-standing evolutionary question of why the human pelvis becomes wider over time? Because the head of a human baby is much larger than offspring of other primates. And, say, chimpanzees can give birth to her cub is relatively easy.
Mitterecker and his colleagues are interested in the issue, developed a mathematical model using data from the world health organization and other major studies on birth. Thanks to the work of experts found two completely opposite evolutionary forces.
According to one of the trends that larger neonates are more healthy. However, if they are in the womb too large, it may not pass through the birth canal, which in the past have led to disastrous consequences for the child and for mother. Their genes would not be passed on.
“selective force – the tendency to reduce the size of the children disappeared through cesarean section. But our goal is not to criticize medical intervention. We only notice that it has led to some evolutionary effect,” says Mitterecker.
Now scientists are wondering what will happen in the future. “I believe that this evolutionary trend will continue, but probably not very rapidly. Everything has a limit, so I don’t think the day will come when the majority of children will be born through cesarean section,” concluded the Austrian researcher.
the results of the study and of the evolutionary changes that occurred through caesarean section, you can read the article in the journal Proceedings of the National Academy of Sciences.
we will Add that earlier it was told that for the sake of safe cesarean section newborns will infect vaginal microbes mother.
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