Sex

This is the name given to any sexual behavior that occurs while asleep. Although there are no statistics, there are some documented cases. In 2004, the Australian doctor Peter Buchanan related the episode of a patient who, although she had a stable partner, went home sleepwalking and had relationships with strangers. And in 2005, the case of a man who was prosecuted for raping the woman he slept with came out in the press.

A group of Spanish researchers from the Almería Arid Zones Experimental Station has come to the conclusion that evolution favors smaller and lighter males, because they can move more easily using their cobwebs, which in turn results in greater opportunities to find a partner.

Scientists at the University of Liverpool have identified a pheromone present in the urine of male mice that irresistibly attracts females. The molecule has been named by its discoverers as "darcin" in homage to Darcy, the hero of the novel "Pride and Prejudice" by Jane Austen.

Since Jane Goodall first observed chimpanzees using grass tools to extract termites in 1960, around twenty contraptions, some quite complex, have been discovered that these primates use for different purposes. The latest finding, made by scientists at the University of Cambridge, is that males in a group of Tanzanian chimpanzees use sexual tools to attract mates.

Promiscuous females could be the key to the survival of certain species, according to a study from the Universities of Exeter and Liverpool in the United Kingdom published in the journal Current Biology. The study could solve the mystery of why females of many species have multiple partners (polyandry) even though this may be more risky on an individual level.

Overweight people have twice the risk of developing erectile dysfunction and obese people are 25 times more likely to suffer sexual problems than those of normal weight, as announced by the Institute of Sexual Medicine. The data is worrying considering that, according to the latest European Health Survey 2009, some six million Spaniards over 18 years of age (17 percent) have obesity problems, almost two percent more than in 2008; and 36.6 percent overweight, one percent more than the previous year.

An Austrian study published in the journal Clinical Endocrinology has shown that testosterone levels in men increase considerably with the vitamin D produced by the body after exposure to sunlight, thus increasing libido. This effect seems to be more pronounced in the summer months.

The mammalian sex chromosome Y, responsible for assigning the male gender, is evolving faster than previously thought, according to a study by the Whitehead Institute in Cambridge (United States). By comparing chimpanzee and human sequences, researchers have detected rapid evolution over the past 6 million years.