GALLONS of blood were spilled by the Aztecs to appease Centéotl, the god of maize. Now someone must have upset him: rising maize prices could force the price of tortillas up by 50%, the makers of the corn pancakes warned last month. That matters: maize remains central to Mexicans’ diet and culture. Each of them gets through 90 kilos of tortillas a year, in tacos, enchiladas or on their own. The price of tortillas worries economists as well, since they make up 1.2% of the consumer-price index.