Health & Science

Trees sprouting in a milder Arctic

Climate change is transforming the stunted shrubs of the Arctic tundra into full-fledged trees, creating a feedback effect that could further promote global warming. Researchers tracked changes in a stretch of tundra between Finland and western Siberia by looking at satellite images and interviewing local reindeer herders. They determined that 30 years ago, the willow and alder shrubs of the area didn’t grow beyond about 3 feet. But now that temperatures have warmed there, 10 to 15 percent of the land is populated by trees more than 6 feet tall. Previously, experts thought that climate change would cause the boreal forests to creep north, “a process that could potentially take centuries,” Oxford University researcher Marc Macias-Fauria tells The New York Times. Instead, the tundra’s usual vegetation has simply grown taller, “transforming into trees in just a few decades.” Though foliage absorbs carbon dioxide, scientists believe the net effect of trees growing in the Arctic is to speed global warming; the trees absorb solar heat that would otherwise reflect off open, snowy ground. That same albedo effect is also happening in the water, as melting ice that used to reflect sunshine is giving way to open water.

A paralysis cure?

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Rats with paralyzed hind legs have regained the ability to walk, and even run, after they underwent a novel combination of treatment and training that researchers hope will one day help humans with spinal cord injuries. Scientists at the Federal Institute of Technology in Lausanne, Switzerland, strapped the rats—whose spinal columns had been damaged but not completely severed—into harnesses that held them upright on their immobile hind legs. After injecting the damaged spines with drugs to promote the growth of new neurons, they beckoned the rodents with chocolate while stimulating their spinal cords with electricity. After two weeks, the rats could take steps toward the treats, and after six weeks, many could run and climb again. “We expected they would recover to some degree, but the extent was amazing,” study author Janine Heutschi tells LiveScience.com. The chemicals appeared to help new neural connections grow around the rats’ spinal wounds, and the electrical stimulation—plus the rats’ own efforts to move toward the food—rerouted communication from the brain to the legs around the injury. Researchers now plan to test similar techniques on humans. Says Australian neuroscientist Bryce Vissel, “We are on the edge of a truly profound advance in modern medicine.”

The smell of the old

There really is such a thing as “old-person smell,” and it is more distinctive and pleasant than the odors given off by young and middle-aged people. Neuroscientist Johan Lundström of the Monell Chemical Senses Center came to that conclusion after having volunteers between the ages of 20 and 30, 45 and 55, and 75 and 95 forgo their usual perfumed products and wear absorbent T-shirts to bed for five nights. The odors from the T-shirts were collected and presented to another group of volunteers to smell. The scent of the older people emerged as by far the most distinctive—volunteers identified it correctly twice as often as they did the other aromas. But they also rated the seniors’ body odor as the least intense and the least offensive among the age groups. While young and middle-aged men ranked as far more unpleasantly odiferous than their female peers, the male scent becomes more neutral in later years, probably due to hormonal changes. “As you grow older, you smell more and more like a woman,” Lundström tells the Los Angeles Times. “It’s almost as if you’re going back to what happened before puberty.”

Galactic turmoil ahead

The Milky Way and its closest neighbor, the Andromeda galaxy, are on course for “a head-on collision,” astronomer Roeland van der Marel of the Space Telescope Science Institute tells ScienceDaily.com. But no need for precautions—the crash won’t happen for another 4 billion years. Researchers have long known that Andromeda, currently some 2.5 million light-years away, is moving toward us at 250,000 miles per hour. Now NASA’s Hubble Space Telescope’s precise measures of the galaxy’s motion show it heading right for the Milky Way. The meeting will be more of a merger than a crash: Since galaxies are mostly empty space, with stars separated by light-years, astronomers say it’s unlikely that any stars or planets will collide. The mash-up of gas and dust from the two systems, however, could give birth to new stars. Any earthlings still around by then would see more stars in the sky. But our solar system will likely remain intact.