The new study results were somewhat surprising, said Copeland. "We assumed more of the hominids would be from non-local areas since it is generally thought the evolution of bipedalism was due in part to allow individuals to range longer distances," she said. "Such small home ranges could imply that bipedalism evolved for other reasons."
First, the results would not have been at all surprising if the scientists understood chimpanzee ethology. Female migration to other troops is a well-established pattern. Why would it be surprising hominids behaved the same way? Also, how many human societies require the woman to leave her family and go live with the husband's family? And in the U.S., how many more male children live at home well into their 20's than female children? This should have been a mere confirmation of the continuity of chimpanzee to human behavior.
The second statement is even more obvious, though. To say that "bipedalism evolved for" anything is a demonstration of a lack of understanding of the nature of evolution. There is not a single trait that evolved "for" anything. A trait evolved, and it if benefited the organisms (or at least didn't harm the organism that much) that expressed the trait, the trait was passed on (assuming no chance loss having nothing to do with the trait per se). Seeing that it is likely that human bipedalism emerged from the upright stance useful in arboreal movements, it is likely to be a merely retained trait, refined by living in grasslands. There is good evidence that bipedalism in fact emerged in forested areas, so it is in fact a preadaptation to grassland living. It also turns out to be very energy-efficient, so retaining it, particularly as the grasslands spread, would have been beneficial as well. Chimpanzees, living in more wooded areas, evolved quadripedalism -- from what was likely a bipedal ancestor, or at least an ancestor that, like bonobos, was partially bipedal.
In short, bipedalism didn't evolve for anything. Those apes that evolved a more upright stance could move through the trees better. And retention of that trait was at least not harmful as the apes moved to the forest floor. Teleological language has no business in statements about evolution from scientists. It only spreads confusion about the nature of evolution.
It would also be nice if scientists knew a bit more about more things than their immediate research. Immediate relations of the studied species comes to mind.