I See What You're Saying
Oh, to be young again! A new study published in the journal Science shows that four-month-old infants can discriminate between languages just by looking at the person who's talking, but by eight months, only bilingual children retain this skill. Researchers showed infants silent video clips of bilingual speakers who first spoke in either English or French and then switched to the other language. Four-month-old and six-month-old infants from monolingual homes paid closer attention to the video—they looked at it for a longer time—when the speaker switched languages. While there was no significant effect in monolingual eight-month-olds, children of this age from bilingual homes also looked longer when the speaker switched. The researchers suggest children in monolingual environments lose the need for this ability sometime between six and eight months into their lives, but children in bilingual situations can still benefit from visually discerning between the two languages.
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Lone Shark
Birds do it, bees do it, and now we know that sharks do it. No, I'm not talking about falling in love. For the first time, researchers have documented a case of parthenogenesis in sharks. After analyzing the DNA of a hammerhead shark born (and killed by a sting ray) in 2001, researchers found no evidence of chromosomal contribution from a male. In a paper published in the Royal Society journal Biology Letters, the researchers conclude that the mother was a virgin when she gave birth to her pup—the daughter was a product of her mom's DNA alone. While scientists had suspected the shark might be a product of parthenogenesis, as none of the females in her tank had had contact with a male in over three years, some chalked it up to hammerheads' ability to store sperm for remarkably long periods of time. But the new DNA tests confirm that sharks have the ability to reproduce all by themselves. While self-impregnation in the wild can be a very bad sign, as it signifies rapidly shrinking populations and limits genetic diversity, virgin births solely in captivity is just kind of cool. Fortunately for us humans, parthenogenesis has never been observed in mammals.
Age is Sexist, Not Homophobic
A new study of nearly 200,000 people aged 20 to 65 has called a winner in several sub-battles of the sexes, and the results are mixed: As expected, men performed better on tasks of mentally rotating objects than women did, while women did better on verbal dexterity tests and remembering object locations. Interestingly, sexual orientation played a role in how ably people performed the tasks: Homosexual people performed worse than heterosexuals, on average, on tests where their sex generally scored higher, and they performed better than heterosexuals on tests where their sex scored lower. On mental rotation tasks, for example, heterosexual men performed best, followed by bisexual men, then homosexual men, then homosexual women, then bisexual women, with heterosexual women at the bottom. The study, which was published in the Archives of Sexual Behavior, also found that men's cognitive abilities declined faster than women's, and sexual orientation played no role in the rate of decline.