How many boys are born for war? Sex or money? Scientists understand why more boys are born on Earth 105 boys are born for every 100 girls

When planning a pregnancy, many future parents begin to worry about the question of how to calculate the sex of the unborn child by the age of the mother as a percentage. Indeed, in fact, some mothers and fathers really want to know in advance who will be born - a boy or a girl! Therefore, here I will present to your attention the exact pregnancy table for 2020. And also I will answer the question, is it possible to calculate the date of conception in such a way that it is a boy or a girl who is born?

In fact, for a long time there has been an ancient Chinese table designed to identify the gender of a future baby and certain signs and signs for determining the sex of a child, which we will consider in this article.

The table below is said to be over 700 years old. She was found in China near the city of Beijing in a crypt.

In order to accurately calculate the gender of the unborn child - a boy or a girl, you need to select the age of the mother and the month in which the conception of the baby is planned in the appropriate column. At the intersection of the vertical column - the month and the corresponding line of the mother's age, you will see the marking "M" or "D", which, respectively, will tell you who will be born to you - a girl or a boy.

For example, if an 18 year old girl or 37 summer woman pregnancy occurred in January, then they are more likely to expect the birth of a girl.

Tables for determining the sex of the child by the blood group of the parents

Keep in mind that this method of determining the sex of a child by blood type in parents cannot be 100% accurate, although many pregnant women use this technique with success.

What is its essence. The sex of the unborn child is determined by correlating the blood type and the Rh factor of the future father and mother. See the special tables below.

Table "Blood type"

Table "Rh factor"

Chinese technique, how to calculate the sex of the unborn baby

You can calculate the gender of the baby using two Japanese tables. Knowing three numbers allows you to get a fairly reliable result.

See:

• in what month the mother was born (first digit);
• in what month the father was born (second digit);
• the month of conception itself (third digit).

The first table is needed to determine the number from 1 to 12. It can be determined by comparing the months of birth of both parents.

In the second table, you should find the number (the result from the first table) and compare it with the month of conception. In this line, sticks (their number) will indicate the chances of the birth of either a boy or a girl. This technique is most relevant for those parents who are at the stage of planning the conception of a baby.

Example: A man was born in April and a woman in June. At the intersection in table No. 1 is the number 10. The month of conception is February. In table No. 2 in column 10 opposite the month of April, we see that the probability of having a girl and a boy is 1 to 1 (one to one), that is, the chances are 50% to 50%.

Table No. 1

Table number 2

We calculate the sex of the child by updating the blood - the table "Boy or Girl"

This technique is very common and free. Its essence is as follows: the blood is renewed at regular intervals, both in the female and in the male. See:

1. In women, the frequency of blood renewal is once every four years.
2. In men, blood renewal occurs once every three years.

Keep in mind that sometimes the process of blood renewal may not occur on the date planned by the body (loss of large volumes of blood due to injuries, transfusions, operations, donation). When calculating, consider these circumstances.

Remembering all the tangible blood loss, determine the year in which the future mother and father had blood renewal. For whom this process occurred earlier, that gender will dominate in the formation of the baby's sexual characteristic. For example, if the mother’s blood was renewed later than that of the father, then most likely a girl will be born, and if vice versa, then a boy.

Who will be born according to the age of the blood?

IN first table we find the renewal coefficients of the blood of the father and mother, opposite the age.

In second table you need to find the number at the intersection of the month of birth of the parent and the month of conception of the child.

Now, for each parent, we add the resulting 2 numbers (from tables 1 and 2). Whoever got the number less (“younger blood”), of that gender is most likely to have a baby. Example: mom is 29 years old, dad is 30 years old. Mom was born in June, dad in March. According to the results of the first table, mom=1, dad=0. According to the results of the second table, mom = 10, dad = 1. According to the results of both tables, mom (1+10 = 11), dad (0+1 = 1). "Dad's blood is younger" - a boy is born.

Determination of the sex of the unborn baby according to folk signs

Basically, the gender of the baby is not fundamentally important to future parents. True, in some cases, moms and dads want the birth of a boy or girl. Is it possible to choose the gender of the unborn child in advance?

How to calculate the sex of the baby by the day of ovulation, who will be born - a boy or a girl

It is natural to assume that when there are two children of the same sex in a family, parents want to diversify their offspring. For example, when there are 2 sons, you want the third child to be a girl and, conversely, if you have two daughters, mom and dad may wish they had a son. And, this is where a reasonable question arises - is it possible to control the very process of conception in such a way as to know in advance exactly who will be born - a boy or a girl? How to do it?

Anyway, we will have to put up with the fact that the process of conceiving a boy or a girl is a great mystery of Nature to some extent. However, scientific minds now have some knowledge of the possibilities of controlling the birth of a child.

The birth of a new human life unequivocally presupposes the meeting of the egg and sperm. It is known that the eggs mature in the ovaries, every month one of the cells leaves the ovary and is sent through the fallopian tubes to the uterine cavity, where it is supposed to meet with the sperm. This process of release of the egg from the ovary is called ovulation.

The life expectancy of an egg after ovulation is only one day and when conception does not occur, it dies after 24 hours. Spermatozoa - male sex cells - are able to live up to five days in the uterine cavity. So, conception occurs when a woman is close to a man on the day of ovulation or a few days before it.

So, who will be born - a boy or a girl, will depend on the quality of the sperm that fertilizes the egg. For the birth of a boy, it is necessary that the sperm contains a Y chromosome, for the appearance of a girl - an X chromosome.

You must know:

• spermatozoa with a male Y-chromosome move faster, but are less tenacious;
• spermatozoa with the X chromosome, despite their slowness, are able to live in the fallopian tube for up to 5 days and, thus, wait for their fusion with the egg!

Therefore, the chances of conceiving a girl are always much greater, which means that sexual intercourse should occur approximately 2-4 days before ovulation!

If you want a boy to be born to you, then calculate the day of ovulation as accurately as possible so that the closeness of a man and a woman takes place on the eve of her onset.

How is ovulation day calculated?

Usually ovulation occurs in the middle of the cycle, but this is not always the case. It is impossible to feel the moment of ovulation, it passes without symptoms. But, you can still calculate this moment using the following methods:

1. Measure your basal body temperature every day for 3-4 months, write it down in a diary and schedule your BBT.
2. Use the most accurate inkjet ovulation test.
3. Get an ultrasound.

To accurately determine the moment of ovulation, a few months before conception, start charting cycles. When the month of conception is chosen, apply another test and undergo an ultrasound.

Signs and fortune-telling on who will be born - a boy or a girl

But, the sex of the child can not always be seen on ultrasound. It happens that a woman, until the very birth, cannot find out who will be born to her - a boy or a girl. That's when folk signs and fortune-telling come to the rescue on what gender the baby will be.

Of course, not all fortune-telling that was popular with our ancestors is suitable for modern women.

I give the simplest folk ways to determine the sex of the unborn baby:

1. Invite the expectant mother spontaneously to raise and extend her arms forward. If her palms are turned up, a daughter will appear, and if they are turned down, a son will appear.
2. Take a large key with a long "beard" and put it on the table. Invite the pregnant woman to take the key and give it to someone present. If the expectant mother takes the key by the top - you should wait for the birth of a boy, and if by the "beard" - a daughter will be born.
3. With the help of fortune-telling with a ring, you can find out who will be - a boy or a girl. Offer the expectant mother to take the “reclining” position, tie a thick thread to the ring and hold the ring by the thread like a pendulum over the woman’s stomach. Gradually, the ring on the thread will begin to swing, if the pendulum moves back and forth or left and right - expect a son, if the ring begins to describe circles above the stomach - there will be a daughter.
4. When a pregnant woman already has children, watch how the hair grows in the child of a previous pregnancy. If the “pigtail” does not grow in the middle of the neck, but on the side, the child of the opposite sex will be born next.

Ways to plan the sex of the child

Diet

• For the birth of a boy, eat fish, meat, mushrooms and potatoes, legumes, chicken protein, apricots and peaches, prunes, rice and semolina.
• For the birth of a girl, give preference to eggs, eggplant and beets, carrots and cucumbers, tomatoes and peppers, honey, peanuts and hazelnuts.

The diet must be followed from the beginning of the menstrual cycle until the moment of the alleged conception - for both women and men. After conception, you can eat whatever you want. The success of this method is about 30%.

Calculation by ovulation date

If sexual intercourse occurred less than a day before ovulation - 10 hours before it - a boy will be born. When sexual contact occurred much earlier or a few days after ovulation, a girl will appear.

You remember that Y chromosomes reach the egg a short period of time before ovulation. If they do not reach it, only the X chromosomes remain to replace them.

Frequency of intercourse

X chromosomes are more mobile than Y, but X has a shorter lifespan. Therefore, with frequent sexual intercourse, the probability of conceiving a boy is very high, and with rare sexual intercourse, a girl. The efficiency of the method is 70-80%.

Posture during intercourse

Some believe that the “man behind” or “woman on top” position contributes to the conception of a boy, and the “man on top” position contributes to the appearance of a girl. This method is based on giving more chances to Y or X sperm. As you know, for the conception of a boy, it is necessary that a Y-sperm cell unites with the egg, and for the conception of a girl, an X-sperm cell.

Even and odd years of a woman

The non-traditional doctor Elena Shavrina revealed the dependence of the sex of the child on the age of the expectant mother. In even years of a woman's life, the conception of a girl is more likely in February, April, June and August, October, December; in odd years, respectively, in January, March and May, July, September and November. The appearance of the boy is the opposite.

These are the main ways to plan the sex of the child. The birth of a child of a certain gender can only be guaranteed by the procedure of artificial insemination - IVF, when an embryo of the desired gender is left in the uterus - a boy or a girl.

Who will be born a boy or a girl - table number 3

See interesting video, which will help you find out the gender of the future crumbs or even plan it.

How to conceive a boy and a girl

Here are 2 videos that will help you decide on the sex of the baby.

There are many more different tables and methods in order to determine the sex of the unborn baby. But let every parent keep in mind that the main thing in a child is not gender, but his health.

There is such a superstition - before the war more boys are born. Few people think about this, referring this statement to women's signs that have nothing to do with reality. But lately, many have begun to pay attention to population growth and wonder if this is true?

Interest in this maxim arose among pundits, physicians and pediatricians, who even conducted scientific developments and research on this topic. The influence of the country's martial law on its natural growth has been studied many times and thoroughly.

What is the result of these studies?

It turned out that the sign has some real ground, but in a slightly different way. Scientists managed to find out that boys were actually born in large numbers, but not before the war, but already during the war and shortly after it. Physicians became interested in this pattern even before the First World War, but at that time there were not enough data, and those that were were not particularly suitable for any serious conclusions.

Immediately after the end of the war with Hitler in Leningrad, the work of the pediatrician Novoselsky was published, highlighting the dependence of the birth rate on military operations. The countries of Europe and Russia were analyzed in the period from 1908 to 1925.

The statistics given in the work of the pediatrician indicate a surge in the birth of male newborns during the war and after it, and before the war everything was as usual. Novoselsky believes that the reason for this can be called a decrease in fetal mortality during pregnancy. He says that during the war the number of conceptions fell sharply, since all the men were at the front. The female body rested from pregnancy, restored the right amount of vitamins, increased its resistance to infections. Therefore, pregnancies occurring against this favorable background were distinguished by a regular and mild course, and miscarriages occurred less frequently.

Novoselsky claims that the normal natural proportion at the time of conception looks like this - about 130 boys to 100 girls. The male fetus is less hardy than the female, therefore, in the first months of pregnancy, it is the male fetuses that die mainly during miscarriages, the proportion of 170 boys per 100 girls. When the female body is in good shape, saturated with vitamins, microelements, has stable strong immunity, all this allows it to successfully bear male fruits and give birth to healthy boys. Another factor in favor of birth a large number boys - primiparous young women whose body has not yet weakened under the influence of many and frequent pregnancies.

Since people are still natural organisms, nature very wisely takes care of balance. For example, scientists from the Institute of Ecology and Evolution are inclined to reasonably assert that, for example, when dogs or other animals are destroyed in the region, a surge in their increased birth rate can be observed. If you follow this maxim, then the appearance of many boys after the wars becomes clear. After all, wars take away a huge number of men, and nature immediately responds to war with a desire for balance.

But today, in our modern times, this fact cannot be explained only by natural wisdom. For example, in China, up to 123 boys appear for every 100 girls, and this is much higher than not only the post-war figures, but also the global ones. China is known in the world for its population policy, the essence of which is to reduce the population of the country. This is done by getting rid of female fetuses, because now you can find out who will be born in the first weeks of pregnancy. Chinese families strive to raise even one child, but a son, so that he would be the breadwinner and helper in old age. Such a policy and nature can not interfere.

In our country, the sex ratio is within the normal range - 105 boys per 100 girls. In this regard, we do not lag behind other countries. Statistics are taken at the beginning of 2007.

Summing up all the above, we can safely say that folk omen about the dependence of boys and war is nothing more than superstition, devoid of any real basis.

A slight excess of newborn boys may depend on many reasons - the country's policy, some natural circumstances, the presence of hostilities, poor ecology, contamination of the atmosphere with toxic substances. Therefore, it is not at all necessary to deal with terrible predictions of war, guided by the birth of beautiful healthy boys.

MOSCOW, August 21 - RIA Novosti, Alfiya Enikeeva. There are many recommendations among the people for those who want to conceive a boy. But they all don't work. It was only by using statistical methods on large amounts of data that scientists were able to uncover hidden factors that affect the sex ratio among newborns. How high incomes of parents and regular sex are connected with this - in the material of RIA Novosti.

crocodile children

When a female American alligator (Alligator mississippiensis) is looking for a place to lay her eggs, she actually determines the sex of her offspring. If the nest is more than 33 degrees Celsius, only boys will hatch from the eggs; at temperatures below thirty, girls will appear.

The sex of alligators, like many species of crocodiles, is determined by the thermosensitive TRPV4 protein contained in the gonads (gonads) of embryos. At high temperature environment it opens access to cells to calcium ions. This activates the genes that ensure the development of the male type - the sections of DNA encoding the anti-Mullerian hormone and the Sox9 gene. Some biologists believe that the regulation of the sex of the offspring allows alligators and crocodiles to maintain an optimal ratio for the survival of the species, when there is one male for ten females.

In all countries of the world, more boys are born than girls. There is evidence that Kazakhstan and Nauru are an exception, there are more female babies (93 to 100), but this does not change the overall picture - a person as a species is trying to reproduce more males.

At the same time, given the poor survival rate of boys during embryonic development (according to various estimates, among miscarriages and stillbirths - up to 70 percent of male fetuses), most experts agree that during fertilization, boys are obtained almost twice as often.

On the other hand, an international group of scientists led by Cambridge geneticist Stephen Orzak recently showed that during artificial insemination, boys and girls are conceived equally, and female embryos die just as often (if not more often) during intrauterine development. Boys die in the first weeks of pregnancy and at 28-35 weeks, for girls the second trimester of pregnancy is more often fatal. Orzak suggests that these results can be transferred to natural fertilization, which refutes the theory of the endurance of female embryos.

© CC BY 4.0 / United Nations Population Division. World Population Prospects: 2017 Revision. The World Bank

© CC BY 4.0 / United Nations Population Division. World Population Prospects: 2017 Revision. The World Bank

Abstinence + stress = girl

1.3. Who is born more - boys or girls?

Back in 1661, it became known that 6% more boys are born in the world than girls (obviously, due to the fact that Y-spermatozoa predominate in the composition of sperm, which ensure the development of the embryo according to the male type of development during fertilization of the egg; on average Y sperm 150–170: 100 X sperm). However, this huge predominance of male gonads does not lead to the same preponderance of born boys over girls, since a large death of males begins already during pregnancy. It is known that the total number early miscarriages accounts for up to 25-30% of all conceptions. It turns out that for 100 miscarriages of female fetuses that occur in the first 3 months of pregnancy, there are 160–170 miscarriages of male fetuses (Novoselsky S.A., 1958). Often the death of the unborn boy occurs before the woman knows that she is pregnant. As a result, only slightly more boys are born than girls. On average, for all races, this ratio is 105.5:100, and in the USSR in 1970 it was 104:100. both religious prejudice (girls are considered undesirable in many families) and demographic conditions (overcrowding). Therefore, for example, in South Korea, 14% more boys are born than girls, and in China even 18% more as a result of the killing of 76 million female fetuses and newborns (Kristof, 1993; Klasen, 1993).

In this regard, three types of sex ratios are distinguished: primary (the ratio of male and female zygotes, or germ cells), secondary (the ratio of the sex of newborns) and tertiary (the ratio of males and females in a mature population among a population capable of reproduction).

The small island of Jinoji in Japan is called the "Island of Boys". For many years, 3.5 times more boys than girls have been born here. Japanese scientists see the reason for this in drinking water - it has a lot of alkaline substances.

B. Ts. Urlanis (1969) cited data according to which 2,098,000 boys and 1,995,000 girls were born in the USSR in 1967. Of these, they did not live to one year: 29 per 1000 boys and 23 per 1000 girls. This trend continued in subsequent years (Table 1.1).

Table 1.1. Infant mortality, 1980–1998 (Zuykova, Eruslanova, 2001)

An interesting fact is that during wars and after them, the number of born boys increases sharply (Fig. 1.2), so that the secondary ratio between males increases in these years and, as a result, the normal ratio, lost during the war years, is restored again.

Rice. 1.2. Dynamics of the secondary sex ratio (Germany 1908–1928)

For example, in Moscow in 1911-1916. the ratio was 104.7:100, in 1917 - 106.9:100, and in 1922–1924, when the First World War and the Civil War ended, the ratio increased to 107.4:100 (Novoselsky S.A. , 1958).

The mechanisms of this natural self-regulation of the sex ratio are not clear. V. A. Geodakyan (1965) put forward as a regulating factor the intensity of sexual activity, which increases the more, the less men remain after various cataclysms (for example, wars) (with a relative increase in the number of young and weak health who are not taken to war) . He supports his point of view by the fact that in animals sexual exhaustion or physical weakness of the producer (male) leads to the predominance of males in the offspring. Thus, in extreme conditions, more males die, but more are born. D. V. Kolesov and N. V. Selverova (1978) do not agree with this explanation, they believe that the sexual activity of male representatives is far from being determined by their relative abundance. Activity may indeed have nothing to do with it, but the state of health of both those who did not fight and those who fought most likely plays a role.

Chapter 2. Morphofunctional Sex Differences

2.1. Morphological differences between males and females

In the first 3 years of life, there are no significant differences in body length and weight, as well as in chest circumference. Boys are slightly larger than girls in body length - up to 10 years, and in mass - up to about 8.5 years. However, due to the earlier (1–1.5 years) onset of puberty, girls begin to surpass boys in body length (from 10 to 13 years) and in weight (from 9 to 14 years). After the age of 12, the rate of growth in girls decreases, and from the age of 14, the rate of increase in body weight also decreases. For boys during this period physical development runs very fast. As a result, at the age of 17, the body weight of boys exceeds that of girls by 12%, and the height and circumference of the chest - by 9%. Men are on average 10 cm taller than women. Male proportions of the body are formed: broad shoulders and back, the pelvis is much narrower than the shoulders, relatively long limbs, the center of gravity is above the waist, while in women it is lower.

J. Tanner (1968) notes that girls are already ahead of boys in terms of ossification(replacement in the skeleton of cartilaginous tissue by bone) by approximately 20%. Ossification of the skeleton in girls aged 10–12 years is 2–3 years ahead of that in boys. However, women have a more fragile skeleton.

M. V. Antropova (1983) provides data on the rate of change in anthropometric indicators in children in relation to the data of adults (definitive indicators), from which it follows that in each age period of childhood, girls morphologically develop at a faster rate than boys (Table 2.1).

Table 2.1. Total increases in the main somatometric indicators of the child in certain age periods of his development (average values, percentage)*

* Note: the absolute values ​​of the somatometric indicators of an adult conditional person, given in the book: “Man. Biomedical data". M., 1977.

According to J. Tanner (1968), the rate of limb development is higher in girls. Already from birth, according to the proportions of the girl's body, closer to definitive(final) condition compared to boys. This is seen in fig. 2.1, where the maturation gradients are presented (the degree of approximation in this moment to the definitive sizes taken as 100%) of the upper limbs in girls and boys.

Rice. 2.1. Gradients of maturation of the upper limbs: 1 - hands, 2 - forearm, 3 - shoulder

The high growth and maturation rates of girls compared to boys can be explained by the fact that in the blood of the former there is a high concentration growth hormone - somatotropin than in the blood of the latter (Fig. 2.2).

Rice. 2.2. The content of somatotropin in blood plasma in children at different stages of puberty

However, it should be noted that all the data presented do not take into account the type of physique of children, which can make significant adjustments to the pace of development of boys and girls. So, according to A. B. Khazanova, the average age of teething is less in girls of only a digestive body type, while in the presence of other types (thoracic, muscular and indefinite), teeth erupt faster in boys (Table 2.2).

Table 2.2. Average age(months) of teething among children infancy Moscow

In six-year-old children, girls of the digestive type are superior to boys of the asthenoid, muscular and thoracic type in terms of weight and chest circumference and are almost as good as boys of the asthenoid type in body length (Table 2.3).

Table 2.3. Anthropometric indicators of six-year-old children depending on the type of constitution (according to T. V. Panasyuk)

Men mature at the age of sixty, and women at about fifteen.

J. Stevens, English writer

Despite the fact that adult women have more somatotropin in the blood than men, they are inferior to men in terms of physical development. This is due to the fact that physical development is also influenced by male sex hormones (androgens), which in men after puberty become much more than in women, and which, according to some scientists, not only affect the development of the body, but also enhance the production of somatotropin. In any case, androgens, even as synergists, enhance the effect of somatotropin in men to a much greater extent than in women.

Women have a shorter length (in Europe - an average of 12 cm) and body weight (an average of 10-15 kg), less strong ligamentous apparatus, narrower shoulders, short and wide chest, a wide and lower pelvis (which leads to a lower center of gravity), a longer torso with relatively shorter limbs (by 10%). The average waist-to-hip ratio for women is 0.7, and for men it is 0.9. In women, lumbar lordosis is more pronounced. For men, body growth ends at 25-32 years, for women - at 17-18 years.

Males have more muscle (active) body mass than females. These differences begin to appear already in young children, when, after the first increase in body fat between the ages of 0 and 6 months, they begin to decrease clearly more markedly in boys than in girls. IN adolescence in boys, this trend continues, and in girls, the growth of the subcutaneous fat layer begins again.

In adult men, muscle mass is about 40% of body weight (average about 30 kg), and in women it is about 30% (average 18 kg). At the same time, skeletal muscles consist mainly of slow muscle fibers (i.e., they contract more slowly than fast muscle fibers), which is biologically expedient due to protracted labor and the need for prolonged straining. Adipose tissue, on the contrary, is more developed in women (due to the innate ability to more efficiently produce fatty substances). On average, in women it is 25% of body weight, and in men - 15%. The absolute amount of fat in women is 4–8 kg more than in men. Since adipose tissue contains almost no water, women's total body water content is less than that of men.

These body features make biological sense. A wide pelvis is a protective bone ring for the internal genital organs and for a child during its intrauterine development; the female pelvis is deeper and larger in capacity, it provides a wide birth canal. In women, the relative length of the spinal column is greater, the interarticular gaps are wider than in men, and the extensibility of the cartilaginous layer filling them is better, which creates conditions for greater flexibility. Shorter legs and a low center of gravity of the body provide stability to the body during pregnancy. Women have a characteristic setting of the head and neck of the femur: they are located at right angles to the femur. This provides a greater range of motion in the hip joint. Large fat pad serves as protection internal organs from blows and gives the body of women rounded shapes. In addition, adipose tissue is an active hormonal organ in which estrogens are synthesized, which determine all feminine qualities. So, for normal menstrual function, a woman needs to have at least 22% of fat mass.

At the same time, the predominance of muscle mass in men is also important in their masculinization, since androgen metabolism occurs in the muscles.

Thus, sexual dimorphism in body size and structure in adults can be explained by: 1) the presence of postnatal maturation gradients; 2) different duration of the prepubertal stage of somatotropin influence; 3) differences in the mechanism of action of androgens and estrogens on the skeletal system. In general, girls from birth are closer to their definitive proportions, in prepuberty they somewhat overtake boys in growth, their puberty jump is observed earlier and less intense. The ratio of body length to limb length in girls is significantly higher than in boys, which is associated with a relative shortening of the somatotropin action phase and early closure of the epiphyseal fissures.

During puberty in boys there is an increase and change in the shape of the larynx. The thyroid cartilage changes especially significantly, forming a characteristic laryngeal protrusion - Adam's apple ("Adam's apple"). His plates converge not at an obtuse angle, as in girls, but at a sharp one. This morphological feature also results in the appearance of a functional feature in men: due to an increase in the volume of the larynx and lengthening of the vocal cords, the voice drops by about one octave compared to the previous period. At the same time, the timbre of the voice and its other qualities change, and the changes are both for the better and for the worse. Therefore, by the quality of a boy's singing in childhood, it is impossible to predict what kind of singer he will become after the breakdown (mutation) of his voice. A sad example of this is Robertino Loretti.

Puberty highlights another difference in the development of the male and female body. In both girls and boys, under the influence of the pituitary hormone follitropin the mammary gland begins to develop: an increase in gland tissue directly under the halo - a pigmented circle of skin around the nipple. However, for the final development of the mammary glands, the friendly influence of follitropin and female sex hormones is necessary. Therefore, such a development occurs in girls, and in boys, who have few female sex hormones, and there is a lot of testosterone, which inhibits the development of these glands, there is a reverse development of the mammary glands.

True, in some teenage boys, the mammary glands can increase to a significant size, this phenomenon is called gynecomastia(from Greek. gyne- woman, mastos- mammary gland). This is due both to the increased release of follitropin and to the increased sensitivity of breast tissue to it.

During puberty, differences between males and females begin to appear in hair growth. The first difference is in the pubic hair. In most men, it is characterized by a wedge-shaped hairline. True, in about every sixth man, the character of pubic hair approaches that of a woman, characterized by an even horizontal line, so that the surface covered with hair has the shape of a triangle, with its apex pointing down.

The second difference in hair growth is that in men, hair begins to grow on the face (first over upper lip, and then on the chin), on the chest, back and legs; distribution of body hair is called hypertrichosis. These features of male hair growth are due to the fact that under the influence of the male sex hormone testosterone, vellus hair turns into so-called long. Different hairiness of men is determined by the different sensitivity of their skin to testosterone and different amounts of this hormone. The latter also determines the fact that hypertrichosis is much less common and less pronounced in women.

In adulthood, the difference in body hair is that many men become bald, but among women there are none.

Summing up, we can say that in terms of the rate of morphological development, girls are ahead of boys, but this does not determine their advantage in absolute morphological indicators, which is increasing every year in favor of boys. So, average weight at the birth of boys, approximately 5% more than girls, and by the age of 20 the difference increases to 20%; an increase in height difference occurs from 1-2% in childhood to 10% by the age of 20.

Gender differences in the representation of morphological types of the constitution. With a large variability of constitution types with age and lifestyle, it can still be noted that according to most authors, males are more likely to have a muscular type, and females have asthenoid and thoracic types (Gordina A.V., Panasyuk T V., 1975; Darskaya S. S., 1975; Lukoyanov Yu. E., Detlaf S. A., 1975; Ryseva E. S. et al., 1975; So, V.S. Solovieva notes that the number of purely muscular type in boys increases with age: from 8 to 13 years old - from 20 to 40%, and at older ages - up to 50%. At the same time, during school age in boys, the percentage of pure thoracic and especially digestive type decreases, which become mixed with signs of the muscular type.

About the differences in the structure of the brain of men and women. IN last years there are more and more publications about differences in the structure of the brain in men and women (Allen et al., 1989; Hines, Green, 1991; Swaab, Friers, 1985; Goy, McEwen, 1980; McLusky, Naftolin, 1981; Kimura D., 1992). Some authors point out that the anterior commissure, i.e., the structure involved in the exchange of information between the hemispheres of the brain, is larger in women than in men. This could explain the great compensatory possibilities noted by neuropathologists in women when one hemisphere is damaged at the expense of the other. However, other researchers have found opposite results: The anterior commissure was larger in men than in women.

Near neurophysiologists found big sizes in men, the third intermediate nucleus of the anterior hypothalamus, associated with behavior, including sexual. However, so far these are only single finds that require confirmation.

2.2. Physiological sex differences

Both in terms of morphological parameters and physiological functions, girls are moving towards their adult status faster than boys (Schneifeld A., 1943), an example of which is their earlier puberty. With regard to the development of physiological functions, another regularity of ontogenetic development is also preserved: every year the differences between boys and girls increase in favor of the former.

The cardiovascular system. The data of physiologists show that in preschool and primary school age the rate of development of girls is higher than that of boys. If in boys the most coordinated activity of the heart and hemodynamics is observed at the age of 11-12, then in girls such relationships take place at the age of 7-8 and 10 years (Kalyuzhnaya R.A., 1983). I. A. Kornienko revealed that the restructuring of physical thermoregulation (a bradycardic reaction to cooling) begins in girls at the age of 5.5–6 years, and in boys at the age of 7 years. This is consistent, the author notes, with the data (Vulfson I.N., Soldaschensky A.D., 1967), showing that in girls 5-6 years old, the speed of the pulse wave through the muscle vessels and the tone of the muscle vessels are higher than in boys of this age. age.

And yet, women have less basic hemodynamic parameters: heart volume - by 100-200 ml, its weight - by 50 g, systolic volume - by 30-40%, minute volume - by 10-15% (despite the greater than in men, heart rate at rest - by 6–8 bpm), circulating blood mass - by 1.2 l, hemoglobin content in the blood - by 1.5 g% (Nowacki P., 1983). In women, the duration of diastole is shorter with a longer phase of blood expulsion. Their heart contractions are weaker, which is one of the reasons for more low level blood pressure. According to a number of authors, given in the summary table by R. A. Kalyuzhnaya (1983), the volumetric blood flow velocity in boys aged 6–11 years is higher than in girls of the same age.

At the same time, females from birth have a number of innate advantages, in particular, greater elasticity of blood vessels. Women may lose more blood than men. For example, the loss of one liter of blood for a man is often fatal, while a woman will endure it without a blood transfusion.

Energy exchange. I. A. Kornienko (1979) showed that in girls at all ages (from 5 to 11 years old), resting energy exchange is lower than in boys (Fig. 2.3).

Rice. 2.3. Changes in the intensity of resting metabolism in boys and girls aged 5–11 years

The same trend was revealed in foreign studies. G. Monod (1973) notes that at rest the level of basal metabolism in men is about 5% higher than in women, and refers to the data of Fleisch (Fleisch, 1951), who summarized the results of various authors relating to several thousand people, and showed that a more intense basal metabolism in men concerns not only children, but also adults (Fig. 2.4)

Rice. 2.4. Change in basal metabolism with age in males and females (Fleisch, 1951)

The capacity of anaerobic energy systems (ATP, CF, glycogen) in women is lower than in men, which is associated not with a lower concentration of these energy sources in the muscles (it is approximately the same in men and women), but primarily with a smaller muscle mass in women. Hence the lower efficiency of women in short-term intensive work.

Respiratory system. Until puberty, when differences in body size between boys and girls are minimal, maximal oxygen uptake (VOC) is also about the same. In young men, BMD is on average 20-30% higher than in women. As we age, the differences in BMD between men and women become smaller (Fig. 2.5).

Rice. 2.5. Changes in BMD with age in women and men

Even calculated per kilogram of body weight, women have less BMD than men. However, among men and women of the same age, there are significant individual variations in BMD values. Physically more fit women have the same BMD as physically poorly developed men.

The lower BMD in women is due to the fact that the maximum amount of oxygen that can be transferred from the lungs to the tissues is less in women than in men. This difference is associated with a smaller number of erythrocytes in women, and, consequently, hemoglobin, a smaller volume of circulating blood (600 ml versus 800 ml in men), a smaller volume of the heart and ventricular cavities, and a smaller systolic volume (Fig. 2.6).

Rice. 2.6. Hematological parameters of men and women at different ages

At the same time, before puberty, the concentration of hemoglobin in the blood of boys and girls is almost the same.

According to T. D. Kuznetsova (1983), up to 12 years of age, gender differences in lung volumes are weakly expressed. This is explained by the fact that the increase in respiratory volume in girls from 6 to 14 years is higher than in boys of the same age, and as a result, the respiratory volume of girls practically becomes equal to that of boys.

In adult women, the respiratory rate is greater than in men, and the depth is less; as a result, the vital capacity of the lungs (VC) in women is on average 1 liter less (according to other authors, even less: 1.7 liters) than in men, and the maximum pulmonary ventilation is 30% (Fig. 2.7). Thus, with age, sex differences in lung vital volume increase. So, in early childhood it is on average 7% higher in boys than in girls, and in adulthood the difference between men and women reaches 35%. In addition, in women, the diffuse capacity of the lungs for oxygen is noticeably lower.

From the age of 6–7 years, the thoracic component of breathing prevails in girls, and the abdominal component in boys.

Hormonal system. V. I. Chemodanov (1983) received data that indicate the presence of significant sex differences in the excretion of catecholamines already in the period of the first and second childhood. The first increase in excretion in girls is 1–1.5 years ahead of that in boys; in boys, this peak is observed at 6–7 years of age, and its amplitude is much greater than in girls. The second increase in girls is observed at the age of 9 and is distinct. In boys, the second peak appears at 10–11 years of age and has a smoothed character. The intensity of the metabolism of adrenaline and noradrenaline in boys is somewhat more intense than in girls.

Rice. 2.7. Maximum pulmonary ventilation at different ages in men and women

The activity of the serotonin system is higher in girls than in boys, and histamine, on the contrary, is higher in boys than in girls.

The most significant differences in the hormonal system in males and females are, of course, in the amount of male (androgens) and female (estrogens, progesterone) sex hormones in their body.

The ancient worldly idea of ​​the eyes as a “mirror of the soul” (pupil size) was supplemented 150 years ago by a scientific conclusion about the eyes as a “mirror of the body”. This second "mirror" is the structure of the iris. A. Ya. Zaitsev and I. M. Paley (1998) combined the study of these “mirrors” and found that the ratio between the pupil area and the iris area in men and women is different. In the male group, the area of ​​the iris exceeds the area of ​​the pupil to a much greater extent than in the female group. This difference in trend is expressed in the fact that the absolute pupil area in women is larger than in men, even in calm background conditions. It is noteworthy that the difference in the relative sizes of the pupil and iris correlates with ergotropism - trophotropism. For men, the predominance of ergotropism is characteristic, and for women - trophotropism.

25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

Even from school biology textbooks, everyone knows that at conception, the probability of the formation of a female or male embryo is correlated as one to one. The sex of the unborn child depends on what type of sperm - containing the X chromosome or the Y chromosome - will fertilize the woman's egg. At the same time, biologists argue that the number of both types of sperm produced in the body of a man is the same, which means that they really have an equal chance of playing a decisive role in determining the sex of a child.

Nevertheless, demographers around the world say:

in fact, more boys are born than girls, and scientists claim that this trend was formed at about the same time as the appearance of the species Homo sapiens.

However, it cannot be assumed that such a picture develops due to the greater mortality of female embryos: medical statistics indicate that during pregnancy, at least in its later stages, it is male embryos that die more often.

These observations led the researchers to conclude that, since male embryos are less viable and their survival rate at the end of pregnancy is still higher, it means that they should significantly predominate over female ones at conception. To date, global statistics show that

105 boys are born per 100 girls (with deviations in different countries from 104 to 107). It turns out that at conception, inequality should be even greater.

This pattern may not hold, for example, in countries where people are moving to new patterns of fertility and the age of the mother is gradually increasing. Demographers and physicians note that as women age, the chances of male embryos to survive become even smaller and the average number of girls born increases.

In Asian countries such as China or India, so-called selective abortions are still common - termination of pregnancy due to the sex of the child, as families strive to have as many sons as possible. American feminist Ann Warren even introduced a special term for this phenomenon - "gendercide" (gendercide). The results of the 2010 census in China showed that 118 boys are born in the country for every 100 girls.

According to statistical forecasts, by 2020-2030, one in five Chinese will be left without a wife.

This generation of forced bachelors, according to experts, can serve as a potential source of social instability.

But even the latest demographic trends could not answer the question: why, contrary to all the laws of biology, do male embryos form more often than female ones at conception? A group of British and American scientists led by Stephen Orzak from the Fresh Pond Research Institute (Cambridge, Massachusetts, USA) managed to reveal all the secrets of the formation of embryos and their further development, and at the same time refute some postulates of demography. An article on the work of researchers was published in the journal PNAS.

Stephen Orzak's group analyzed information about children conceived in the US, Canada and some other European countries from 1995 to 2004. Scientists paid attention not only to natural pregnancies (in this case, the sex of the child was determined on the 3-6th day after conception using amniocentesis - analysis amniotic fluid), but also on pregnancies formed with the help of in vitro fertilization. The researchers also took into account data on miscarriages and artificially terminated pregnancies.

In total, scientists have collected information on approximately 31 million embryos, which is an absolute record in studies of this kind.

Determination of the sex of the child at the earliest stages - during the first week of pregnancy - showed that in fact the laws of biology are not violated: the number of male and female embryos at conception really turned out to be the same. The opinion about the non-viability of male fetuses has also been refuted. In fact, boys are more likely to die only during the first one or two weeks of pregnancy and at 28-35 weeks. In the rest of the period, the mortality of female embryos is much higher.

Thus, scientists managed to refute two postulates of modern demography at once: about the disproportion of the sexes at conception and about the weakness of the health of male embryos.

The researchers do not exclude that the results of their work will force demographers to reconsider some provisions of their science.

Despite the fact that researchers have been able to prove the validity of the laws of biology, you should not think that future parents can in no way increase the likelihood of conceiving a boy or girl. So, an obstetrician-gynecologist of the highest qualification category Georgy Mestergazi notes that the activity of spermatozoa depends on whether they are “male” or “female”. "Female" X-sperms can be compared to long-distance runners: they are larger, more tenacious, move more slowly and can move through the fallopian tubes for a sufficiently long period of time, and then "wait" for ovulation for about 72 hours.

But Y-sperms are more like sprinters that move quickly and over short distances: they are more likely to fertilize an egg if they are close to it. It turns out that the likelihood of conceiving a son or daughter can change depending on where the ejaculation occurred: near the cervix or vagina. Moreover, “male” and “female” spermatozoa feel differently in different environments: the first is favored by an alkaline environment, the second by an acidic one.