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.

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.

Popularity Mechanics
Repeating the same argument over and over won’t make you right, but it might give your opponent the impression that your opinion is commonly held.  According to a study recently published in the Journal of Personality and Social Psychology, when people hear one opinion repeated several times, even if it was from the same person every time, they are more likely to believe it is a popular opinion. Researchers divided over 1,000 subjects into three groups: One group read three opinion statements from three different people, one group read (the same) three statements all attributed to one person, and one group read only one statement with a single author. Subjects were more likely to assume that the opinion was the majority opinion when one person repeated himself than when there was only one statement, and hearing one person several times carried almost as much weight as hearing opinions from three different people. The authors say their study could have implications for understanding how influential people gather information about group opinion. “For example, a congressman may get multiple phone calls from a small number of constituents requesting a certain policy be implemented or changed, and from those requests must decide how voters in their state feel about the issue,” said Virginia Tech psychologist Kimberlee Weaver, the lead author. “This study sheds light on the cognitive processes that take place that may influence such a decision.”

Who’s Your Daddy?
When Missouri passed the law saying a paternity test must come back with at least a 98 percent probability of a match for a man to be named the legal father, perhaps some enterprising young litigator said, “But what if two identical twins have sex with the same woman on the same day, and they both have strong paternity test results? What do we do then?” A recent court case has shown the worry to be legitimate. Paternity test results showed that identical twins Raymon and Richard Miller each have over a 99.9 percent probability of being a three-year-old girl’s father. As the two have exactly the same DNA, the test cannot distinguish between the two men. Since the mother tagged Raymon as the father, and the test results are good enough, courts have asked Raymon to pay child support as the little girl’s legal father. But Raymon is contesting the decision, saying that because both he and his brother had sex with the mother on the same day, he really has only a 50 percent chance of being the girl’s father, and the law should not compel him to pay for the child. The judge insists he does not have to rely solely on DNA evidence when assigning parenthood.

Originally published May 29, 2007

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