Health & Science

The 4,000-year-old man

He had coarse brown hair that was probably receding, brown eyes, darker skin than most Europeans, and lived 4,000 years ago. Using a tuft of hair found in the permafrost (it may have been snipped off during a haircut), scientists have re-created most of the genome of a member of Greenland’s extinct Saqqaq culture, producing a vivid insight into what ancient peoples looked like. The man’s DNA shows that his closest living relatives are the Chukchis, who live in easternmost Siberia. That indicates the Saqqaqs arrived in Greenland through a previously unknown migration from Siberia across North America. The individual Saqqaq that was studied had a gene variant that made his hair nearly as thick as a bear’s, but he also carried a gene that made him prone to going bald. Since hair preserves DNA better than flesh or bones do, the nearly complete analysis of the man’s genome opens the door to studies of the physiology and migration patterns of other ancient peoples, from pre-Columbian tribes in South America to the mummies of Egypt, researcher Eske Willerslev of the University of Copenhagen tells New Scientist. “Nobody really knows where the limits are,” he says.

A strange Botox side effect

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Botox injections that eliminate frown lines may interfere with people’s ability to perceive sadness and anger, a new study says. University of Wisconsin researchers studied 40 people who had received Botox treatments that paralyzed muscles that produce frowns. Both before the injections and afterward, the subjects were asked to read statements designed to evoke strong feelings (“the pushy telemarketer won’t let you return to your dinner”), and then to push a button to indicate whether they understood them. After the Botox injections, patients had trouble processing and understanding sentences about anger, irritation, and sadness. This phenomenon apparently relates to the “facial feedback” effect, in which the muscles used in smiling, frowning, and other emotional expressions send signals back to the brain, strengthening and making us aware of these emotions. On the one hand, researcher David Havas tells Discovery News, Botox might make people slightly happier by blunting their awareness of negative feelings. On the other, “we might miss subtle cues telling us things aren’t going well.”

Parental age and autism

The older a mother is at the age of conception, the greater her risk of having a child with autism, new research has found. The University of California at Davis study, which analyzed all the births in California over a decade (and included 12,000 autism cases), found that every five-year increase in a mother’s age at conception raised her risk of having an autistic child by 18 percent. A 40-year-old mom’s risk was 51 percent greater than that of a woman in her late 20s. Older fathers also had a greater risk, but with a curious twist: Autism occurred more frequently in children born to fathers over 40 only if their wives were under 30. When the mother was over 30, the father’s age seemed to have no effect. Researchers cautioned that advanced parental ages account for only a small part of the startling, 600 percent increase in autism cases over the past two decades. “The rise in autism is occurring among children of parents of all ages,” researcher Janie Shelton told The New York Times. Autism is a brain disorder that leads to poor social and communication skills and to repetitive behaviors. Its cause remains unknown, although research has indicated that accumulated DNA damage in parents and an autoimmune response in the maternal womb may play a part.

Beer builds bones

In moderation, beer can be a health-food drink that builds strong bones, says USA Today. University of California researchers have found that beer is a rich source of silicon, which increases bone mineral density and helps prevent osteoporosis. The food scientists tested 100 commercial beers for silicon content, and found that pale ales had the highest levels, while light lagers and wheat beers had the lowest. “Beers containing high levels of malted barley and hops are richest in silicon,” said researcher Charles Bamforth.

The cause of stuttering

Why do some people stutter? For years, doctors have theorized that it’s the result of an emotional disorder, anxiety, or poor parenting. But a new study of hundreds of stutterers in Pakistan, Britain, and the U.S. has found that the speech disorder arises from a genetic mutation in three genes. The mutation affects cells in the brain involved in speech, and hampers the cells’ ability to break down and get rid of cellular wastes. When this “recycling” process gets interrupted, says researcher Dennis Drayna of the National Institute on Deafness and Other Communications Disorders, “the cell goes haywire, and that causes problems.” The misfiring of these cells, he says, is what causes stuttering. About 3 million people in the U.S. stutter, and about 60 percent of them have a family member who stutters. “It’s just great news for people who stutter to know that it’s a gene,” Tammy Flores, executive director of the National Stuttering Association, tells CNN.com. “It’s not anything else. It’s a gene.”