Sharply rising food prices have often meant trouble for governments, especially when people expect better and the cost of food is a big fraction of average household consumption. In the U.S., where grocery costs are a small fraction of the average budget, it is hard to imagine the effect of sharply rising prices for bread or rice, cooking oil, and other essential foods. It's seldom been enough for out-of-touch regimes to say, "let them eat paistries" (or brioche, as Marie Antoinette put it in the face of the French revolution).

In what countries is a big fraction of the average household budget gobbled by purchases at the produce market, bakery, and butcher? Based on data from Nomura, Business Insider claims that the highest percentage occurs in Nigeria (70%). and that every North African nation is among the top 25. (Disclosure: I once spent a year in Tunisia after it won independence from France and before it hosted the Palestinian leadership). The first of the recent headlines about riots against the regime came out of Tunisia (36% of household consumption spent for food) and Egypt (48%). Algeria has not been quiet (53%). All are in North Africa, along with Morocco and Libya.

Other countries where a large percentage of the average household consumption goes for food: former states in the USSR such as Ukraine and Azerbaijan (both around 60%), Bulgaria and Romania; Vietnam (all three around 50), African countries such as Sudan, Angola and Kenya; and our sort of ally, nuclear-armed Pakistan (all around the high 40s).

Of course, each country's situation is different. Other factors include: how much of the food produced passes through the cash economy, the degree of urbanization, drought caused by climate change, the rate of population increase, expectations, usefulness to global capitalism, degree of democratization (if any), the ruthlessness of the regime.

If governments are felt to have an overriding task, other than defending the borders, it's filling stomachs with at least a minimum of calories. So far, some regimes have depended on torture in private and tear gas in public to cow their malnourished people.

Meanwhile, the Food and Agriculture Organization (FAO) in Rome has published statistics showing a sharp rise in food prices.

It''s exhilarating to cheer on street demonstrations against dictators, but emotions here will be mixed if the agitation spreads to countries, such as Saudi Arabia, on which the U.S. and allies depend for oil. So far, we have supplied regimes with money for "humane" crowd control (water canons, tear gas, rubber bullets, truncheons), pretended to take seriously fake elections, and sent certain countries terror suspects who are secretly tortured; then we chastise the countries for not respecting human rights.

To what extent are we like the Vichy police chief in the movie Casablanca who is routinely allowed to win at the cafe's crooked routlette wheel, but who, seeking a reason for shutting down the establishment at the command of the visiting Nazis, announces that he's "shocked, shocked" to find there's gambling going on?

Lester Brown, to his credit, keeps bringing our attention to the shortage of affordable food, caused by paving over of crop land, the exhaustion of aquifers,climate change, the rising cost of fuel caused by peak oil and of fertilizer, financial speculation, and other factors. If people can't afford to eat, some may conclude they have little left to lose, and especially young men may take to the streets, thinking the government is not only cruel but also unfair and incompetent.

The usual answer of governments is repression under the guise of "keeping order." If the rulers have socked away fortunes outside the country, they may be forced to flee, and while unhappy to give up power, at least can live in luxury.

So if we seek an indicator of the potential for anti-regime riots, look at the rate of food price increases in countries where the fraction of the average household budget for food is high. Already, some observers are spreading the meme that poor people abroad just want "dignity." Surely they do, but that desire can be squashed for decades. What is harder to deflect, as the French elite discovered in the 18th century, is desperation over the lack of affordable food.

In Tunisia, I tutored a son of the ambassador of an Islamic country, a son who would drive me around the capitol in his father's yellow Mercedes convertible. His distinguished father had backed the losing side in a coup and been sent abroad to keep him out of politics. When the boy mentioned that his household included spies for the regime, I said naively, "that's horrible." Taking his eyes off the road, the lad replied, "but, sar, it is normal."

Secret services and police can keep control under many circumstances, but sharply rising food prices may challenge their stealthy dominance.