Testosterone for men, without exaggeration, is one of the key hormones: puberty and the ability to have children depend on it, it also largely determines the behavior and appearance of men (testosterone, for example, affects the development of bones and muscles, which means growth and body weight).
For different people, its level can differ markedly, although remaining within the normal range. What determines the level of testosterone? From genes, from lifestyle, from nutrition and from other factors.
The testosterone level of a newly-made father drops sharply after the birth of a child, and caring for a son or daughter only enhances this effect – it is this switch to the “father’s program” that may be the reason that family men are on average healthier than bachelors, according to the authors of an article published in the journal Proceedings of the National Academy of Sciences.
Caring for the offspring is quite common for most species of mammals, but in most cases only the female takes care of the cubs, while the “father of the family” loses its interest almost immediately after mating. At the same time, males and females of many species of birds – for example, ostriches, pigeons and penguins – look after their offspring together.
As a rule, a high level of testosterone in the blood of males of these species, preceding mating, is replaced by extremely low values after the birth of cubs. Scientists believe that at this moment the so-called “paternal program” is activated, which forces the male to switch from searching for new partners to care for the offspring.
“People have a rather unusual position among mammals, because the survival of our children depends on adults who feed and protect them for more than ten years. Breeding is a difficult task for humans, and it inevitably requires mutual assistance. Our study showed that fathers biologically “programmed” to help mothers, “said one of the band’s members, Christopher Kuzawa, whose words are quoted in a statement by a scientific organization.
A group of biologists led by Lee Gettler of Northwestern University in Evanston (USA) estimated changes in saliva testosterone levels in 624 young Filipinos, about a third of whom managed to turn from single people into family men in 4.5 years of research with respect to testosterone voice change permanent occurrence.
Scientists twice collected saliva samples from volunteers – in 2005 and 2009. Both times, scientists evaluated evening and morning testosterone levels. Then they compared the data of the analysis of samples with data on changes in the lives of participants in the experiment and their survey on its results.
It turned out that men with initially high levels of testosterone were more successful in family life than those whose concentration of this hormone was low. In addition, the appearance of a child in the family, especially the first-born, sharply lowered the level of testosterone in the blood of men: over the 4.5 years of the study, the concentration of testosterone in the saliva of fathers decreased by 26-34% – much stronger than the usual “age-related” drop in the level of this hormone in 10-13%.
In addition, even less male hormone was in the saliva of those men who spent 1-3 hours or more daily on raising their sons and daughters. At the same time, scientists emphasize, it cannot be said that men with lower testosterone levels are simply more inclined to take care of children – a statistical analysis showed that the initial level of male hormone in a bachelor in 2005 was in no way connected with the subsequent attitude of the young father to children.
Researchers believe that good health and lower mortality among family men compared to bachelors can be attributed precisely to a switch to the “paternal program” and a decrease in testosterone levels. As previous studies have shown, a high level of this hormone can increase the risk of prostate cancer and high blood cholesterol, as well as increase the propensity, for example, to alcohol and drugs.