It could be an unintended consequence of the rise of sex selection, according to Mara Hvistendahl:
Several Indian sociologists I interviewed mentioned that perhaps the one silver lining in this disaster is the fact that dowries are decreasing in the northwestern Indian states where sex selection has left many more men than women. But what has replaced dowry is bride-buying, which is hardly ideal, either. … And dowry still persists symbolically in northwest India. One sociologist told me locals have simply adapted it to the times. A man might slip the parents of the woman he’s buying a little extra money—and then the parents hand the money back to him as dowry.
The Dish 