Almost 40 million Africans — almost 10 million more than the population of Canada — are short of food, left to rely on aid to stave off hunger and even starvation.

Perhaps as troubling, though rarely mentioned, is that almost all of these people live within 100 miles of well-fed towns. Farms just a few hundred miles away can have bumper crops.

Generous people around the globe reach into their pockets to help aid groups that care for malnourished children with bloated stomachs and dehydrated mothers nursing skinny babies.

Many people, however, wonder why African countries still suffer from famine. Other parts of the world experience droughts, crop failures and other calamities without anyone starving. Why can't Africa feed itself?

Hunger is nothing new in Africa. Ninth century religious documents in Ethiopia describe the slow death of hundreds of people on the rocky northern plains. In the early 20th century, draconian colonial policies to placate urban residents and civil servants during food shortages often left many in the majority rural population to die.

But starving Africans didn't really enter global consciousness until 1971, when tens of millions of people went hungry and more than a million died in Mali, Mauritania and Niger.

Heart-wrenching scenes from the 1984 famine in Ethiopia — the first such crisis to be widely televised — gave a new impetus to relief work. Bob Geldof formed Band Aid to raise money, and the following year, Michael Jackson and Lionel Ritchie provided a theme song, "We are the World."

Yet Africans still periodically suffer critical food shortages.

The World Food Program says poor harvests have left 4 percent of Africa's population — 23 million people in the south, 13 million in the Horn of Africa and 2 million in the west and center — without enough food.

The agency said Jan. 29 that only an emergency operation to ship in hundreds of thousands of tons of food had staved off starvation in six southern countries.

Most famines are blamed on droughts, but many experts say crop shortages are predictable, and famine is preventable.

At the Famine Early Warning Center in Nairobi, scientists study the climate, infrastructure, economics and politics that combine to bring hunger and death. For these experts, rainfall is only one of many enemies.

"I think people tend to overestimate the importance of climatic factors as causes of food insecurity," said Nic Maunder, the center's specialist for the greater Horn of Africa region.

Maunder says war, bad governance, disease and poor roads and other infrastructure play equally important roles, but the biggest factor is poverty.

"It's usually an access question, not an availability question," Maunder said, noting that famines can occur in countries that appear to have plenty of food.

Food security is not merely about the food supply but an individual's ability to buy it, he said. Famines almost never occur in cities or large towns, where incomes don't depend on agriculture.

Maunder said Ethiopia is a classic example. Farmers in western Ethiopia produce consistent bumper crops, while crop failures in the east bring food shortages every four to five years that usually leave 5 million to 10 million people hungry.

"Those people in the east are on the edge of destitution all the time, so if their crop fails they can't afford to buy the crop coming from the other side of the country," Maunder said.

Ethiopia, like most African countries, has a poor road system, which means sometimes it is cheaper to ship food from the United States than to truck it across the country.

But the injection of foreign food can harm local economies. An excess of free food can drive down the price of locally grown food, leaving local farmers without enough income to buy seeds for the next season. Improperly managed, temporary food aid can lead to permanent food dependence.

Corruption and mismanagement also are factors.

Aid workers widely blame Malawi's food shortage that began last year on the illegal sale of the national corn reserve and the embezzlement of the profits. Zimbabwe's food crisis is linked to President Robert Mugabe's seizure of white-owned commercial farms for redistribution to black subsistence farmers, resulting in a 60 percent drop in production.

In Angola, where civil war has destroyed the agricultural sector, officials and workers in the state oil industry skim off profits while the United Nations struggles to feed millions of rural poor living in refugee camps.

The contrast can be seen in Namibia and Botswana, two prosperous, well-governed nations in southern Africa. While caught in the same drought that has brought hunger to Angola, Zimbabwe and Zambia, those two nations require almost no outside aid to feed their people.

On a whiteboard hanging on the wall of his Nairobi office, Ron Senykoff has drawn a telling graph with a red marker. As regional director of the U.S. Agency for International Development's Food for Peace program, he keeps tabs on the continent's food supply.

Senykoff's graph has two horizontal lines. The top one is a series of waves. Along the bottom, a straight line slowly sinks. The top line is the rainfall cycle: a perpetual series of good and bad years. The bottom line shows the declining ratio of farm land per person as Africa's population has more than tripled since 1970.

With the amount of land per person dropping, the shock waves caused by the rain cycle are amplified, Senykoff said. There are no more natural disasters in Africa now than decades ago, only three times as many people to suffer from them, he said.

Senykoff's job is to give away the surplus food grown by American farmers and bought by the U.S. government. The World Food Program gets about 60 percent of its food from the United States.

He said his team works hard to meet the legal requirement that American food not disrupt local markets. They watch the price of grain closely and check to see if donated food is being sold in village markets. But he admits that if faced with letting people starve or hurting the local economy, he'll make sure people get food.

There are 53 countries in Africa, and agriculture remains the main economic driver for all but a handful. Experts say they need to modernize their economies and move away from subsistence farming, as China and India have.

African leaders should look at crops where they have an advantage, rather than strive for national self-sufficiency, Maunder said. For example, he said, because Kenya makes good money exporting green beans to Britain and France, Kenyans could buy their staple food — corn — from Uganda instead of trying to grow it themselves as they do now.

But most African countries are in an almost decade-long economic slump, beset with rising unemployment and political instability and have no money for modernizing.

The economic downturn began with the collapse of prices on global commodity markets, where most African countries made most of their money from tropical products like cocoa, coffee and tea.

African leaders argue that developed nations impede truly free trade in farm goods and prevent Africans from earning enough to diversify economies.

Speaking at the World Food Summit in Rome last June, Ugandan President Yoweri Museveni said Africa could feed the world — if trade barriers were removed.

"Let us stop beating around the bush, the most fundamental problems are not the weather (or) lack of improved seeds," said Museveni, whose country produces surplus food. "The main causes of food shortages in the world are really three: wars, protectionism in agricultural products in Europe, the U.S.A., China, India and Japan, and protectionism in value-added products on the part of the same countries."

Experts note, for instance, that Washington promotes international trade as the best way to reduce poverty, but it hurts Third World farming by subsidizing American farmers who put cheap food on the global market.

Maunder said Africa may not now be self-sufficient in food, but has potential. War-ravaged parts of southern Sudan and eastern Congo have millions of acres of good land that can't supply markets because of fighting.

A drive through parts of rebel-held Sudan finds thousands of mango trees producing more fruit than local people could ever consume. Some areas report a surplus of sorghum, the staple food. But the war prevents it from getting to drought-stricken regions where people must rely on handouts of American corn.

Near Bunia, Congo, farms that once produced wheat under Belgian colonial rule lie fallow. A few hundred miles away, people survive on corn and vegetable oil delivered by expensive U.N. cargo planes.

Although the prescriptions for fighting famine are widely known among professionals, they say it won't be easy persuading people in faraway lands to help pay for new roads and a modern market in Africa or simply give up their farm subsidies.

But without changes internationally, and more importantly in Africa itself, the experts say hungry children, desperate mothers and broken men will dominate the headlines every three to five years.