The fact that in the last two centuries the development of children has become faster is no secret. How logical it was, the phenomenon was attributed to changes in economic conditions, but also of better hygiene, prevention of infections, etc. But the phenomenon seems to have not stopped, more, continued even in the last ones 2 decades. Whatever the reason?
Different paces of development in different communities
What has changed during this time?? Pesticides in the environment, which have an effect similar to estrogens, sex hormones, were considered responsible. There are cases, described in the specialized literature, which demonstrates the influence of pesticides on sexualization. But in man (in Romanian I don't know how to say it without being misogynistic), indisputable cases are rare. Sure, in other vertebrate species, fish and amphibians, things are much clearer. To species (Pest) in which there is no sex chromosome, this is given by the genes, which can be influenced by hormones. The same individual can become female or male depending on the environment. How some pesticides have estrogen-like effects, the gender ratio has changed, which can lead to the disappearance of the respective species.
A recent study conducted in the USA shows that women enter puberty earlier than the old textbooks showed, but also the studies from the 90s. Something very interesting comes into play here, the age of puberty decreased in a higher percentage for black and Hispanic girls than for "white" girls. Some signs of puberty appear at 7 years at 10.4 % among whites, the 14,9% in Spanish if 23, 4% black girls, because at 8 years the percentages be 18,3%, 30,9% and 42,9%. The study shows that the age of puberty in black and Hispanic girls dropped even from 1997, from another study that signals this phenomenon. White girls who show signs of puberty earlier are...fat, what, consider the authors, it could lead to confusion, that is to say, in some cases, fat, but not the development of secondary sexual characters. Instead, no sign seems to suggest that the age of puberty has changed in normal-weight white girls.
History and reproduction
authors, as seen in the article, I can't find the explanation for this situation. Because I don't know evolution:)) These results can even be called predictions of the theory from "Civilization". In humans, reproduction has some presented characteristics, among others, by Desmond Morris in "The Empty Monkey". These are low fertility, consumption of resources at the expense of the mother, not of the chicken as in other mammals, and others are the placenta with a special structure, able to absorb nutrients in large quantities, but also the baby is very large at birth compared to other primates, although he is immature. Unaided mammal pups are usually small, and if they are big, they are independent (the terms are altricial and patricial).
Human reproduction seems to bear the imprint of crises (I don't say adapted to crises anymore). In "Civilization" things are dealt with extensively. But what needs to be said is that animals subject to caloric restriction live longer, but their fertility decreases. A question I heard at a congress (it was addressed to someone who was talking about the effects of caloric restriction) why the positive effects of caloric restriction are not generalized in nature. Beyond the fact that animals live with caloric restriction in nature, the problem is with reproduction. If an individual adapts to hunger through other phenomena than the decrease in fertility, has an advantage over those with clean arteries, but little fertility.
An experiment carried out with vinegar flies shows how things are. Musculitas had their eggs taken away when they were young, only the "old" ones being left to reproduce. The effect- after a number of generations, the lifespan of midges has doubled. But in nature, such a thing is not very possible. Because flies that reproduce faster are favored by selection. This is also true for humans? More, there could be differences in different communities?
Human communities have a different history not only depending on exposure to famine, but also of reproductive practices. Some have been practicing agriculture for thousands of years, others for several centuries. Agriculture, with all its problems, it means greater food security. In farming communities, contrary to what is believed, women do not marry very young. I remember that at an exhibition of handicrafts, a client asked an Indian salesman at what age their women get married. to 20, as in rural communities in Europe. Roma are nomads, they have different customs compared to the Indians who have been farmers for thousands of years, like most African communities, former hunter-gatherers. In hunter-gatherer communities, the emergence of fertility almost coincides with marriage. The prediction that will be? Women from poor communities, with a long history of crisis (but not necessarily very long, sometimes the effects of the environment are rapid, v. "Civilization"), in which there was also encouragement of early reproduction (it usually is), it will develop reproductively faster when the environmental conditions change. Black girls come from Africa, more, they have an American history of poverty. Hispanic women mostly have the genes of those desperados, which says a lot about them.
The phenomenon also existed among Europeans, continue to some extent, but it is all the more intense the greater the selective pressure of the environment and the more it has changed. It stopped in normal weight white girls, according to the study. There could be several links between obesity and early reproduction. As for the risk of developing certain forms of cancer and early fertility, maybe the connection would have another component, that is, common cellular mechanisms more than exposure to hormones. Give and investigate.
Anyway, the reason for the decrease in the age of puberty is the access to abundant food. Not only that the food became even richer, some poor communities until recently have access to cheap and high-calorie foods, but these phenomena can intensify over the generations ("The Civilization of Hunger" presents other examples). As for reproductive practices, patriarchy could, through these phenomena, influence the health of future generations, that is, to be harmful to women's health in the long term, but not only theirs. Because that selection of reproduction at very young ages could have multiple effects. Another prediction of the theory would be a certain reserve distribution in women who reproduce younger. This is also to be investigated.
As for the article about sexualization and early puberty, it's cool. There are studies that somehow show that girls who masturbate from a young age have earlier puberty? Then how the images on TV sexualize them more than the sex itself? The fear of sexualization through images is for parents, to protect themselves. In history, children were not so naive (as I am not even now), excessive modesty also comes to Europe with Christianity, i.e. still a patriarchal religion.
http://www.nytimes.com/2010/08/09/health/research/09puberty.html?_r=2
http://www.9am.ro/stiri-revista-presei/Social/151872/STOP-Sa-nu-ne-mai-sexualizam-fetitele.html
