Health & Science

The ancient lakes of Mars

Mars was warm enough 3 billion years ago to be laced with large, interconnected lakes and rivers, spectacular new satellite images show. The finding, based on photos by NASA’s Mars Reconnaissance Orbiter, adds to a growing body of evidence that the Red Planet has a wet history—and possibly could have once harbored life. The orbiting spacecraft identified several large lake beds that scientists once thought were just depressions in the surface. Close analysis of the new images revealed connecting channels that could only have been created by flowing water; scientists compared the formations to areas seen today in Alaska and Siberia where melting permafrost creates drainage channels. The lake beds, up to 12 miles across, are thought to have formed during a brief warming spell 3 billion years ago, perhaps caused by volcanic activity or meteor impacts. Previous research has suggested that Mars harbored lakes and rivers early on, but had turned arid and cold by 3.8 billion years ago. For scientists hoping one day to find fossilized signs of microbial life, the lake beds are “another place to go and look,” study co-author Sanjeev Gupta, of Imperial College London, tells BBCnews.com. Just a few months ago, the NASA mission discovered another possible location for past or current life—a vast sheet of ice lying just beneath the Martian surface.

Hubble spots oldest galaxies

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The refurbished Hubble Space Telescope has served astronomers yet another treat: a glimpse of “the oldest galaxies yet seen,” says ScienceNow. Images taken with Hubble’s new infrared Wide Field Camera 3 revealed seven faint, star-forming galaxies more than 13 billion light-years away, at the very edge of the visible universe. Scientists believe that the galaxies, which are a fraction of the size of our Milky Way galaxy, formed between 600 million and 800 million years after the Big Bang; that would make them 200 million years older than the earliest galaxies previously observed. “With the rejuvenated Hubble and its new instruments, we are now entering uncharted territory that is ripe for new discoveries,’’ says Garth Illingworth of the University of California, Santa Cruz.

G-spot or not?

The G-spot, the famed erogenous zone said to lie hidden in a woman’s vagina, just got a little more elusive; in fact, it may be no more than a myth, a British study now contends. Since the 1950s, when this pleasure zone was first described by German gynecologist Ernst Gräfenberg, scientists have attempted to pinpoint where and what exactly it is. The new study involved more than 1,800 female twins, some identical, some fraternal. The twins were asked if their sexual experiences indicated the existence of a G-spot, on the premise that identical twins (who share identical genes) would be more likely than fraternal twins to both report having sensed one. The identical twins were no more likely than other women to say that they had such an erogenous zone, the researchers found. The study “shows fairly conclusively that the idea of a G-spot is subjective,” says study co-author Tim Spector. “It is virtually impossible to find.” Critics called the study flawed, with Indiana University sex researcher Debby Herbenick noting that a majority of women have experienced evidence of a G-spot. “I don’t think that these are invented experiences at all,” Herbenick told CNN.com. “And if at the end of the day, someone’s invented something and they feel pleasure from it, then I think that’s great.’’

Antidepressants: Costly placebos?

Some 30 million Americans take medication to treat depression, but for most people, antidepressants serve mostly as a placebo, scientists now say. Researchers at the University of Pennsylvania reanalyzed six major studies, involving several hundred patients, that had sought to determine whether antidepressants (including Paxil) were more effective than placebos at treating the subjects’ symptoms. They found that the benefit of the drugs rose with the degree of depression: The most severely depressed patients saw their conditions improve, but the rest saw no improvement compared with patients who simply took a placebo. In other words, study co-author Robert DeRubeis tells The New York Times, many of these patients felt somewhat better, but that may have been a function of believing the pills would help them, or of the attention they received from doctors prescribing the medication. “The message for patients with mild to moderate depression,” he says, “is, ‘Look, medications are always an option, but there’s little evidence that they add to other efforts to shake the depression—whether it’s exercise, seeing the doctor, reading about the disorder, or going for psychotherapy.’” The study does affirm the value of medication for people with acute depression, says psychiatrist Erick Turner, but it “could dampen enthusiasm for antidepressant medications a bit, and that may be a good thing.” One out of 10 Americans is taking antidepressants.