KISSING COUSINS HAVE MORE KIN
Icelandic women born between 1800 and 1824 who mated with a third cousin had more children and grandchildren (4.04 and 9.17, respectively) than women who mated with someone no closer than an eighth cousin (3.34 and 7.31). Those proportions held up a century later, when family size shrunk. Mating with a relative might reduce a woman’s chance of having a miscarriage caused by an immunological incompatibility with her child. There is a limit to family closeness, however: couples that were second cousins or more closely related did not have as many children, probably because the kids inherited mutations that cut their lives short.  —Nikhil Swaminathan

Running Dialogue
New languages spin off from older ones with an initial burst of alterations to vocabulary before settling down and gradually changing over time, British researchers report. The group focused on three major language families: Bantu (Swahili and Zulu, for example), Indo-European (English, Latin), and Austronesian (Tagalog, Seediq). Some 10 to 33 percent of divergence between languages stemmed from key vocabulary changes at the time of language splitting.

This discrete evolutionary pattern occurs when a social group tries to forge a separate identity, the researchers say, citing as examples the sudden emergence of American English when Noah Webster published his dictionary in 1828 and, more recently, the development of black American English.  —Nikhil Swaminathan

Not Going Out to Play
Americans are losing interest in going outdoors. Researchers analyzed trends in visits to parks and forests and in licenses for activities such as hunting and fishing. All peaked between 1981 and 1991 after 50 years of steady increase. But since then, they have been declining at roughly 1 percent each year, an overall drop of as much as 25 percent. Electronic diversions may be taking over; increasing school and work pressure and “stranger danger” fear absent in previous generations may also be contributing.  —David Biello

Knee-Jerk Power
A 1.6-kilogram knee brace worn while walking could power portable devices and prosthetic limbs. Developed by researchers at Simon Fraser University, the brace generated about five watts of electricity per person during a recent experiment, enough to run 10 cell phones concurrently. One subject generated 54 watts by running in place. To capture this energy, the brace relies on gears, a clutch, a generator and a computerized control system that monitors the knee’s angle to determine when to engage and disengage power generation. The researchers targeted a particular part of the stride: halfway through the swing of the lower leg after it has left the ground through the time the foot returns to the ground. By tapping into unconscious muscle movements, this and other electricity-from-motion devices are more likely to be used. The researchers describe the brace in the February 8 Science.  —Larry Greenemeier

Eye on the Illusion
Ambiguous images seem to flicker between two alternatives, as if the brain cannot quite make up its mind how to perceive them. The Necker cube, for instance, sometimes looks as if it is pointing into the page and sometimes appears to point out. In an experiment on six volunteers with different kinds of ambiguous visual and auditory stimuli, Christof Koch of the California Institute of Technology and his colleagues found that the pupils dilated around the time that perception shifted. The extent of the momentary dilation, which could be as much as one millimeter, also correlated with how long that particular perception lasted. (Pupils span about two millimeters under bright light.) Because the neurotransmitter norepinephrine controls the pupils, the compound may also play a role in rapid, unconscious decision making. Take a look at the study in the February 5 Proceedings of the National Academy of Sciences USA.  —Philip Yam

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