The old saying that every society is only three meals away from revolution is as true now as ever.
Soaring food prices are among a range of issues that have brought long-standing grievances onto the streets, threatening regimes in Tunisia, Egypt and beyond. In February, prices hit an all-time high, spelling bad news for dictators everywhere.
But it could be a massive investment opportunity as the global agricultural industry reverses years of slack investment to supply growing demand. So should you be putting your money where your mouth is?
After two decades of fairly stable prices, food stockpiles have plunged in recent years, says Hugo Rogers, the manager of the UK-based Thames River Water & Agriculture Absolute Return Fund, which invests in food and water companies.
The first food shock came in February 2008, when world grain inventories dipped below 70 days of supply. Prices soared and people rioted as far apart as Bangladesh, Cameroon, India and Yemen.
But it was followed by two good harvests and food prices stabilised again, Mr Rogers says.
"Despite a respectable harvest in 2010, grain inventories have once again dipped below 70 days, as producers struggle to keep up with rising global demand. Unless we have a massive harvest this year, inventories will remain low."
The latest spike in the price of foods such as corn, cocoa, wheat and coffee is partly caused by poor harvests brought on by adverse weather.
But even an Englishman can't blame it all on the weather.
"People in emerging markets such as China and India are shifting to protein-based diets, which places more pressure on producers - it takes seven kilograms of grain to produce just one kilogram of beef," Mr Rogers says.
"Another problem is that more productive land is being set aside for biofuel. One quarter of the US grain crop is fed to cars, not people. This also forces up food prices."
The Green Revolution of the 1960s, which saw dramatic improvements in agricultural yields, has long since played itself out.
"At its peak, yields were increasing by 20 per cent a year. They are now as low as 1 per cent a year. Even with genetically modified [GM] foods, we're not getting much more output per hectare."
Some blame overpopulation, but don't panic, we're not going to starve. If Latin America, Europe, Asia and Africa lifted their crop yields to US levels, we could feed three planets, Mr Rogers says.
"In Brazil, 30 per cent of grain never makes it to market. In India, 40 per cent of vegetables rot. This is down to poor infrastructure, transportation and central logistics. As food prices increase, investors have a real incentive to reverse this."
So is now a ripe time to invest in the sector?
In the spring of 2008, when food was in short supply, "soft" commodity prices such as grain, corn and sugar grew at a record rate, only to wither and die in the summer as supply increased.
Agriculture has bloomed again since then and there is more to come, says Gert van de Geer, the manager of the Pictet Agriculture Fund. "The ideal time to invest was in early 2009, after commodity prices had crashed. That is always the best time to invest, when everything looks horrible. Shares in agricultural companies have rallied strongly since then, but the long-term outlook is still excellent."
The only way the world can supply enough food for itself over the next few decades is to pour money into agriculture. "We need more fertiliser, better transport, improved infrastructure, higher yields, fewer trade barriers and less waste. Agriculture has to become more technically sophisticated, with more mechanisation and better seeding, ploughing and spraying."
Investors can benefit right across the food chain, from investing in fertiliser producers, farming companies, palm-oil plantations, port operators, rail terminals and traders who store, handle and process food into other products, he says.
Agriculture is a growth area now, but be warned: it is highly cyclical. Two good harvests and supply could quickly outstrip demand again, forcing prices down.
"Nobody can say how long the cycle will last. It partly depends on weather shocks. But the long-term outlook remains extremely attractive because food production has to keep up with the growing global population," says Mr van de Geer.
Food has been a fertile sector for the clients of James Thomas, the regional director at Acuma Wealth Management in Dubai. "I have advised my clients to invest in this sector for the past couple of years," he says. "There is only a finite amount of arable land, but an increasing population. But this is a high-risk sector and I wouldn't recommend investing more than 10 per cent of your portfolio here."
Investing in food companies is different from the rather more controversial practice of speculating on prices.
Last year, a campaigning charity called the World Development Movement accused hedge funds, including Goldman Sachs, of gambling with the lives of the poorest by speculating on food prices.
Investment does the opposite by helping to feed the world, Mr Thomas says. "It leads to innovation and development that boosts total food production and investors deserve to be rewarded for the risks they take."
Most private investors should avoid speculative vehicles in any case, says Steve Gregory, the managing partner at Holborn Assets in Dubai. "You can invest in the world's futures markets through vehicles such as AMT Futures, from fund manager CFP Funds, but these are high risk and only for experienced investors. They trade currencies, bonds, precious metals and crops, but this is effectively speculating with future prices and not for everybody."
Investing in agriculture is a great way to diversify your portfolio and you can do it via a mutual fund that invests in the shares of food production, processing and distribution companies.
Mr Gregory recommends DWS Global Agribusiness, from Deutsche Bank, which invests across the food-supply chain.
"This claims to be the first fund that invests along all parts of the agribusiness chain, from farm to fork. It has returned 22 per cent in the last six months, but be aware, future returns may be volatile."
He is also in favour of the Thames River Water & Agriculture Absolute Return Fund.
This fund aims to compensate for the cyclical nature of this sector by shorting markets where necessary and seeks to deliver a consistent return of about 15 per cent a year.
After years of underinvestment in farming and a fall in the amount of arable land, agriculture is blossoming, with a fresh focus on using fertilisers to boost yields, according to a new report from fund manager Fidelity International.
Food producers in countries with relatively low costs should reap the benefit, says Nick Price, the manager of Fidelity International's Europe, Middle East and Africa fund. "Clover Industries, for example, is the largest dairy company in South Africa and well placed to benefit from growing demand for dairy products."
Another way to invest in agriculture is through a specialist exchange traded fund (ETF) that tracks specific soft commodity prices. ETF Securities offers a range of specialist agriculture funds, including ETFS Cocoa, ETFS Coffee, ETFS Grains and ETFS Wheat.
The recent performance of ETFS Wheat shows just how volatile this sector is. It has thrived lately, growing 11 per cent in the past month and 47 per cent over the past 12 months, according to figures from trustnet.com.
But over three years, it would have been a blight on your portfolio, falling a rotten 53 per cent. Are you prepared for this level of risk?
Food prices will probably stay high for the next few months, says Mr Rogers at Thames River. "El Niño has hit soya-bean production in Latin America," he says. "Heavy rainfall in South East Asia and Australia has pushed up the price of crude palm oil, rice and wheat. We can expect further price peaks throughout the year. Things are going to get worse before they get better."
At some point, this will reverse. "With prices high, farmers are planting as much as they can," Mr Rogers says. "There has been a wave of mechanisation. If this leads to an increase in supply, prices could fall. Yet we believe that in the long run, both supply and demand are favourable for positive returns."
Climate change has grafted another volatile element to this sector. "We have seen a massive increase in the frequency and strength of extreme weather patterns in recent years, hitting the wheat and sugar harvests. The current La Niña could be the strongest ever recorded and follows an extremely strong El Niño two years ago. This makes food production even more uncertain."
Social unrest in the Middle East could accelerate food price increases, as governments try to prevent contagion from Egypt by stockpiling food and restricting agricultural exports. Oil at US$100 (Dh367) a barrel may also force up prices by increasing the cost of producing and transporting food.
People have to eat and the food industry is the most important on the planet. The biggest danger you face is investing at the wrong point in the agricultural cycle.
Unfortunately, nobody knows when that is until it is too late. One bad harvest and prices can spring upwards. A good harvest and they can wither on the vine. This is one investment where your fortunes really do change with the seasons.