It may win the prize for the strangest place to get a back massage. The womb provides the first opportunity for touchy-feely social bonding, according to new research published  in PLoS ONE. Scientists tracked the motion of five pairs of twin fetuses using ultrasonography, an imaging technique that visualizes internal body structures. By the 14 th week of gestation, the fetuses began reaching toward their partners, and just 4 weeks later, they spent more time touching their neighbors than themselves or the walls of the uterus. In all, almost 30% of their movements were directed toward their prenatal companions. These movements, such as stroking the head or back, last longer and are more accurate than self-directed movements, such as touching their own eyes or mouths. The findings suggest that twin fetuses are aware of their counterparts in the womb and prefer to interact with them. Or as the authors put it, they're "wired to be social."
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