BROTHERS TO BLAME
PARIS
The more older brothers a boy has the likelier he is to be a homosexual, says a theory aired in the New Scientist in light of a Canadian researcher's findings that boys with a statistical average of 2.5 older brothers are twice as likely to be gay as boys with no older brother, while those with four older brothers are three times as likely.
The study was led by Ray Blanchard, psychologist at the Center for Addiction and Mental Health in Toronto.
Blanchard broke ground in gender science a few years ago when he was struck by a strong link between homosexuality and older brothers in a group of 302 gay white men. His notion was at first ridiculed but is now accepted by many in his field, and other studies have taken this idea further, suggesting that the link exists regardless of culture, New Scientist says.
Why there should be this association is unclear.
One idea is that male fetuses trigger a response in the mother's immune system through an antigen H-Y that only exists in males and is believed to play a role in sexual differentiation. It could be that, among some women, these H-Y antigens unleash a surge of maternal antibodies that then affects the organization of the fetus' brain at a critical early stage of its development, Blanchard suggests. No similar link has ever been found between lesbians and older sisters.
The research raises intriguing questions, the New Scientist article says.
"If Blanchard is right, then clearly, as average family size decreases, so will the incidence of male homosexuality. It also follows that historically there have been more gay men than there are today."
If this theory is right-conservative religious groups like Catholics and Mormons, which are traditionally hostile to homosexuality, may proportionately have more gays than other sects because they encourage large families.
AFP
THOUGHT AND FUNERAL
PARIS
Spanish researchers say a pink stone used as an axehead 350,000 years ago could be the earliest evidence of funeral rites. The quartzite stone, carefully sharpened to form a chopping edge, was found among the fossilized bones of 27 humans at the bottom of a 14-meter deep pit inside limestone caves at Atapuerca, near Burgos.
Previously, the earliest known funeral rites dated back 100,000 years. The dating is important because these rituals reflect the dawn of abstract thought. The research was led by Eudald Carbonell of the Rovira i Virgili University in Tarragona, who said the exceptional color of the stone may have given it special value. It is the only man-made implement in the pit, and it may have been placed there intentionally as some symbolic gesture, according to his interpretation.
AFP
PENIS WITH FEELINGS
PARIS
Doctors who have grown penile tissue in animals to demonstrate the possibility of organ replacement have now gone one better-they have added nerve cells-to allow sensation.
The team led by Anthony Atala at Boston Children's Hospital made the breakthrough September last year when they replaced missing chunks of penis in live rabbits with tissues grown in the lab. The replacement tissue comprised only muscle cells and endothelial cells-cells that make up the inside of blood vessels.
This time, they have regrown penile nerve cells, using millimeterwide channels of collagen as a supporting structure, like insulation around electrical wires, New Scientist reported in its web site. The experiment, conducted on live rats, showed that collagen supported nerve cells grew just as well as nerves that were grafted onto the severed penile stumps of the luckless rodents.
"The nerve cells are very important-they are responsible for all the sensory function," Atala was quoted by New Scientist as saying.
AFP
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