The human species presents individuals with separate sexes, that is, it has males and females. Biologically speaking, men and women have very marked differences, both anatomically, physiologically and genetically, which characterizes «sexual dimorphism».
Topics of this article
→ chromosomal differences
We know that in human cells there are 23 pairs of chromosomes. Of these, 22 pairs are autosomes and the other two chromosomes (1 pair) are called sex chromosomes. Autosomal chromosomes are common to both sexes and do not have marked differences between them; however, the sex chromosomes determine the characteristics of a male and a female. In women, the presence of two X sex chromosomes, which are homologous, is observed. In men, on the other hand, the presence of an X chromosome and a Y chromosome is observed.
→ hormonal differences
Men and women have sex hormones in different amounts that ensure the development of primary and secondary sexual characteristics. Men have a higher concentration of androgenssuch as testosterone, unlike women, who have a higher concentration of estrogen.
Androgens are related, among other functions, to the inhibition of breast development, vocal cords elongation, laryngeal growth, development of body hair, sebaceous gland activities and effects on libido. Estrogens, in turn, promote the development of the uterus and ovaries, act on the breasts and play a fundamental role in menstruation.
→ sexual maturity
At puberty, the period in which the biological maturation of the organism occurs, the development of secondary sexual characteristics is observed. In this phase, marked changes occur in both men and women, making them capable of reproduction.
Generally speaking, puberty begins earlier in girls than in boys. In girls, from the age of 8, the appearance of breasts is already observed; and around the age of 12, the first menstruation occurs. In boys, the volume of the testicle begins to increase around 11 years old, pubic hair begins to appear around 12 years old and hair on the face only at 15 years old.
→ information processing
Male and female brains do not work the same way, showing slight differences in the way they process information and emotions. Some neurophysiologists explain that men are better at calculations than women, who, in turn, deal better with human relations and language. These differences are probably related to the orientation of connections between neurons.
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Another interesting point in relation to the male and female central nervous system is that women have more gray matter (a region with cell bodies of neurons) when compared to men, who have more white matter (formed by extensions of neurons).
→ Performance in physical activities
Men and women also show differences when it comes to performance in physical activities. In the case of aerobic exercises, men have advantages, as they have a greater number of red blood cells, which are responsible for transporting the oxygen necessary for cellular respiration (the process of energy acquisition by the cell). In terms of strength, men also have advantages due to the greater production of testosterone, which causes a greater increase in muscle. Women have greater flexibility, which ensures better execution of activities that require precise movements.
→ amount of fat
Women have a greater amount of body fat when compared to men. This greater amount of fat is normally associated with the fact that the woman is carrying the baby, therefore needing an additional source of energy. Many researchers associate the fact that man has less fat and more muscle to his role as a hunter in the early days of human evolution.
→ Differences in voices
Men and women also have typical voice differences, with men’s voices being lower than women’s. In men, the vocal folds are thicker and more elastic, vibrating more than 120 times per second. In women, vibration occurs more frequently, these folds being thinner and more tense.
It is worth noting that hormonal changes are responsible for voice changes. If a woman, for example, receives testosterone, the voice will become more masculine, since this hormone is related to the increase in the mass of the vocal folds.
By Ma. Vanessa dos Santos