Following the deregulation of the finance markets in the early 00s (whose bright idea was that?), finance people have discovered food commodities as a new toy to play with, and the prices have become unpredictable and decoupled from the real world parameters such as supply and demand. While the guilty parties deny that their gambling has any impact on the real world, experts increasingly believe that speculation does drive real people into real hunger.
For more info about this scandalous situation (and some of the science behind it, including, again, herding), read my feature in today's issue of Current Biology:
Don't play with food
Current Biology, Volume 21, Issue 19, pages R795-R798, 11 October 2011
summary and free access to pdf file
On the same issue, the World Development Movement (also mentioned in my feature) have today issued a press release:
450 economists call on G20 finance ministers to stop speculation fuelling hunger