Health & Science

Our inner Neanderthal

When the ancestors of modern humans, Homo sapiens, migrated from Africa to the Middle East and Europe some 50,000 years ago, they met up with a separate hominid group, the Neanderthals. Scientists have long wondered how those two groups got along during the 10,000 years they co-existed, and a new study offers a humbling answer. An analysis of the Neanderthal genome indicates that between 1 percent and 4 percent of the human genome comes from Neanderthals, suggesting that with surprising frequency, the two groups made love, not war. Neanderthals “are not totally extinct,” geneticist and study author Svante Paabo tells BBC.com. “In some of us they live on, a little bit.” It’s the most solid evidence yet for an affair that anthropologists have long suspected; still, many are “surprised by the amount” of interbreeding that went on, says John Hawks, of the University of Wisconsin-Madison. The greatest amount of Neanderthal DNA can be found in Europeans and Asians, while native Africans have virtually none, because humans did their fooling around with Neanderthals only after groups of them left Africa. The finding profoundly alters our understanding of what it means to be human, says Hawks. Neanderthals are “not ‘them’ anymore,” he says. “They’re ‘us.’”

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Working mothers take heart: Biochemically speaking, a phone conversation with your kid is as good as a hug. Previous studies have shown that close physical contact spurs the release of oxytocin, the “love hormone,” which helps promote bonding between a mother and her child. To see if a phone chat could have the same effect, researchers in Wisconsin administered a stress test to several dozen girls, ages 7 to 12, in which they had to give a talk or do math problems before an audience of strangers. Afterward, a third of the girls were hugged and soothed by their moms for 15 minutes; another third talked with their moms on the phone; and the rest watched a movie. Stress levels did rise in the girls in the movie group, but dropped an equal amount for girls who’d interacted with their mothers either in person or on the phone. Likewise, both the phoned and the hugged girls released similar levels of oxytocin. “That a simple telephone call could have this physiological effect on oxytocin is really exciting,” study co-author Seth Pollak tells Scientific American. For years, Pollak had seen students call their mothers immediately after an exam. “Maybe it’s a quick and dirty way to feel better,” he concedes, and “not pop psychology or psychobabble.”

Why we sigh

A sigh is more than just a sigh. In fact, it plays a critical role in helping the respiratory system run properly, says Discovery News. To understand what sighs have to offer, Belgian researchers rigged seated volunteers with sensors that monitored their breathing, heart rate, and blood carbon-dioxide levels for 20 minutes. When subjects spontaneously sighed—a deeper, slower breath—the dynamics of their breathing changed to become briefly more effective. The results suggest that a sigh “acts as a general resetter of the respiratory system,” study author Elke Vlemincx says. Under stress, our breathing becomes less responsive to the need for more or less oxygen, and the lungs stiffen and become less effective at exchanging gases. But a sigh shakes up the system, loosening up the lungs and allowing for more flexible breathing.

Of mice and pain

For an accurate measure of a mouse’s pain, just look at its face. Researchers in Canada have found that, when subjected to the varieties of pain that often arise in lab experiments, mice make an array of facial expressions similar to human ones. “This is the first study that has examined facial expressions of pain in nonhuman animals,” psychologist and study co-author Kenneth Craig tells Scientific American. Craig and colleagues filmed mice for a half-hour before and after injecting them with a weak and mildly painful vinegar solution. The scientists then created a “mouse grimace scale” that correlated changes in their subjects’ faces—closed eyes, bulging cheeks, or retracted ears—to the degree and duration of their pain. The researchers think the pain scale may apply to other mammals as well, and could help test how well painkillers and other medications work in animals, says co-author Jeffrey Mogil. “We think in a sense that we can rewrite the veterinarian rule book.”