Discovered: Some of our DNA is four-stranded, and that's not a good thing. the brain's selfishness center; men who can't smell don't have much sex; hearing loss foreshadows mental decline.

Quadruple-helix DNA discovered. Cambridge University researchers just made a discovery that upends one of our most fundamental understandings about genetics. In grade school, everyone learns about the ladder-like double-helix structure of DNA—well as it turns out, some of the DNA in our bodies is built from four strands, and it could play a role in cancer. These quadruple-helix strands have been artificially created in labs, but Cambridge chemistry professor Shankar Balasubramanian and his colleagues have located them for the first time in human bodies, inside cancer cells. The G-quadruplex molecule they've isolated have an abundance of guanine. These square-like strands of DNA replicate much more quickly than double-helix formations, making the quadruple-helix discovery particularly notable for cancer researchers. "This research further highlights the potential for exploiting these unusual DNA structures to beat cancer, and the next part of this is to figure out how to target them in tumor cells," says Julie Sharp from Cancer Research UK, a group that funded the research. [BBC News]

A strategic bump on the head can cure overly selfish people. A new paper in the Proceedings of the National Academy of Sciences purports to have pinpointed a region of the human brain associated with selfishness. How did the scientists come to that conclusion? By studying people who'd received damage to the basolateral amygdala. When this area was compromised, subjects were likely to trust complete strangers with large amounts of money. They generously entrusted strangers with twice the amount of money as the control group, who had no damage to the basolateral amygdala. [Science News]

Without smell, men become more celibate. Men who can't smell tend to be more chaste than men able to pick up on odors. A paper titled "Men without a sense of smell exhibit a strongly reduced number of sexual relationships, women exhibit reduced partnership security – A reanalysis of previously published data" reports this intriguing finding: 

Olfaction seems to play a key role in mate choice and helps detecting emotions in other people. In a previous study, we showed that people who were born without a sense of smell exhibit enhanced social insecurity. Based on the comments to this article we decided to have a closer look to whether the absence of the sense of smell affects men and women differently. Under this focus questionnaire data of 32 patients, diagnosed with isolated congenital anosmia (10 men, 22 women) and 36 age-matched healthy controls (15 men, 21 women) was reanalyzed. In result, men and women without a sense of smell reported enhanced social insecurity, but with different consequences: Men who were born without a sense of smell exhibit a strongly reduced number of sexual relationships and women are affected such that they feel less secure about their partner.

[Discover]

Hearing loss doesn't bode well for mental functions. In aging, the decline of auditory perception is often a canary in the coal mine of mental decline. Johns Hopkins researchers have found that hearing loss often foreshadows memory and other cognitive problems. In elderly patients undergoing hearing loss, the researchers noticed overall mental function declining 30 percent to 40 percent faster than in comparable peers who maintained hearing. "Our results show that hearing loss should not be considered an inconsequential part of aging, because it may come with some serious long-term consequences to healthy brain functioning," says researcher Frank Lin, assistant professor at Johns Hopkins' School of Medicine. "Our findings emphasize just how important it is for physicians to discuss hearing with their patients and to be proactive in addressing any hearing declines over time." [Johns Hopkins]