In the early 1980s, long before he became an expert on HIV, Daniel Halperin took a part-time job as a cabbie in San Francisco.

The work happened to give him a clear view into the city’s lively—but newly suffering—gay culture. Many of his customers were men on their way to clubs and bathhouses, he says, and some were visibly sick with AIDS.

The disease was a terrifying mystery back then. No one knew how to treat it or where exactly it had come from.

Halperin chatted with the customers, listened to their stories, and waited with the meter running while they left to engage in the kind of casual sex that was helping to spread the virus.

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Halperin, now an epidemiologist and medical anthropologist at UNC, has been a student of human communities and the cultural aspects of diseases such as HIV for most of his career. What he learned during his cabbie days, and then later during his travels to Africa to study AIDS prevention, stuck with him.

The story we’re told about AIDS is incomplete, he says. While we know a lot more about the origins of the virus today than we did thirty years ago, there are still a lot of myths and misconceptions, not to mention many untold stories of how Africans have fought the epidemic.

To help fill in the gaps, Halperin and Washington Post editor Craig Timberg worked together to write Tinderbox: How the West Sparked the AIDS Epidemic and How the World Can Finally Overcome It.

Their new book tells the story of that critical moment in history when simian immunodeficiency virus was transmitted from a chimpanzee and reborn inside a human as HIV. Of how the brutal, lucrative business of colonialism inadvertently helped to fan the flames. And of how we could stamp out the epidemic by addressing its main (but taboo) driver: sexual behavior.

HIV’s origin story

HIV was born long before we managed to give it a name, Halperin says. And after years of genetic sleuthing, scientists have finally drawn its family tree.

The virus’s roots are in the dense, forbidding jungles of southeast Cameroon. For millennia, the resident chimps (known as the Central Chimpanzees) have been infected with the chimp version of HIV—simian immunodeficiency virus.

Their version of SIV is the one that most resembles the deadliest and most common version of HIV, called HIV-1 group M.

These chimps, researchers concluded, were most likely the source of the outbreak. At some point, the blood of one of the infected chimps must have mixed with that of a human.

The dominant theory, Halperin and Timberg explain, is that a hungry porter—most likely employed by some Western explorer—cut himself while butchering an infected chimp for bush meat.

After the virus passed to the human, it mutated, eventually turning into the human immunodeficiency virus.

To find out when this happened, scientists studied the oldest samples of HIV they could find. These happened to be taken in the late 1950s in a hospital in Kinshasa, a city down the river from that Cameroonian jungle. After calculating how many viral generations it would have taken to bring about the changes between those samples and samples from infected Central Chimpanzees, researchers narrowed the time frame to an astonishingly early date: around 1908.

It’s likely that SIV was transmitted to humans and became HIV hundreds of times throughout history before 1908, when it finally came into a world where it could become a pandemic, Halperin and Timberg say. There may have been occasional small outbreaks over the centuries, but they would have fizzled out before the virus could spread to the rest of the world.

For HIV to proliferate, Halperin and Timberg explain, it needs a lot of hosts, all moving around and having sex with multiple partners over a long period of time. But human beings have always been few and far between in that part of Africa.

That is, until the late nineteenth century.

The Scramble for Africa

To the rest of the world, Africa was the great unknown, said to be brimming with riches. Droves of Europeans and Americans began flocking there in search of rubber, ivory, and cheap labor. Western governments snatched up huge swaths of land, all struggling to claim control of people and resources.

Soon the newcomers built roads through the jungles and sent the first steamships chugging up the Sangha River, “opening a new era of fast, long-distance trade routes on which a fragile young virus could have hitched a ride,” Halperin and Timberg write.

Colonialists also established cities in Central Africa where people gathered in greater numbers than ever before. Smallpox and syphilis epidemics blossomed in their wake.

Along with all the adventurers and fortune-makers came another group that Halperin says incited huge changes in the way people lived, especially in their sex lives: religious missionaries.

The missionaries were horror-struck by the culture of polygamy they found, and worked tirelessly to eradicate it. They convinced their converts that polygamy was evil. Many men stopped marrying multiple women and instead married only one. People didn’t, however, stop having sex with multiple partners—they just became more secretive about it.

Central Africa’s sexual culture began to shift. Instead of a husband and several wives having sex within a closed relationship, many people looked outside their marriages for discrete sexual encounters with more casual partners. These happen to be ideal circumstances for HIV to flourish.

Without what historians call the Scramble for Africa, Halperin and Timberg argue, HIV could not have escaped the jungle. But with the help of unprecedented traffic, growing cities, and changing sexual behaviors, the virus managed to make its way into enough bodies to gain a foothold in the broader human population.

HIV simmered in Kinshasa for a few decades and then, when Belgium’s colonial rule ended and the Congolese were allowed to travel freely again, the virus exploded into the rest of the world.

“Colonialism had had the effect of transforming the region into a tinderbox capable of creating the AIDS epidemic,” Halperin and Timberg write. “Then it fanned the flames.”

Sexual pastures

Since 1981, when AIDS cases were first identified, more than 30 million people have died from AIDS-related causes. Today, an estimated 34 million people are infected with HIV.

Antiretroviral therapies and other medical advances have pulled us away from the horror of those early days of the AIDS epidemic, when a diagnosis was essentially a death sentence. But the real advances in stopping the spread of the virus, Halperin says, have come from changes in sexual behaviors.

He saw the changes firsthand in San Francisco. Casual sex fell out of favor in the gay community. Bathhouses closed. The government and nonprofits started aggressive campaigns to educate Americans about prevention.

Condoms played a significant role in slowing the spread in the United States and many other Western countries. Maybe that’s why the West became fixated on the idea that condoms were the main solution in Africa, too, Halperin and Timberg say.

Western countries shipped countless crates of condoms overseas and urged Africans—through posters, billboards, and doctors—to use them in every sexual encounter. But condoms are a relatively new phenomenon in Africa, and many people still see them as inherently foreign.

The condom crusade failed to take hold in most African countries, including Uganda, which saw one of the worst AIDS outbreaks on the planet. An inspired move by the Ugandan government, though, did lead to one of few successful efforts to control the spread of HIV in Africa.

Ugandan officials conducted a campaign of public awareness and education that was almost unheard of in Africa, where most countries were embarrassed by the reputation the virus had bestowed on their continent and preferred not to speak of it—or even to admit its existence.

The Ugandan campaign was called Zero Grazing. It encouraged people to be faithful to their spouses and not graze in sexual pastures beyond their polygamous marriages. Part of the reason it worked, Halperin and Timberg say, is that the government didn’t try to completely change the traditions and culture of the polygamous Ugandan people.

Traditional polygamy, when practiced strictly, is not especially risky, Halperin and Timberg say, because the husband and wives form a closed sexual circuit that keeps out new infections. “But the modern variant of polygamy that had become common during colonialism and its aftermath—when multiple wives were replaced by a succession of informal, often overlapping relationships—was portrayed as alien, decadent, and deadly,” they write.

Many Western experts dismissed the effort at the time. They thought it wasn’t effective because the number of new infections seemed to continue to rise. But they didn’t realize then that those “new” infections were actually people who had been infected as early as ten years before. (That’s how long it takes the virus to show itself in most cases.)

In hindsight, experts can see that Zero Grazing was unusually effective in stopping the spread of not only HIV but many other STDs as well. Over the course of the campaign, researchers found, casual sexual relationships in Uganda declined by roughly 60 percent.

Yet to come

The need to treat HIV patients is urgent, Halperin and Timberg say, and Western scientists have made great strides in that field. But prevention, which is somewhat less glamorous in the eyes of Western donors and gets far less funding, is the only way to stop the spread of the disease. And it begins with understanding sexual behaviors.

Since Tinderbox came out, Halperin says, a lot of people have asked him: If the West and colonialism are responsible for starting the epidemic in Africa, shouldn’t the West be responsible for fixing it?

Colonialism was driven by greed, and today’s Western altruism is, of course, not the same thing. But they share something of which many Africans are now mistrustful, Halperin says: foreign intercession.

It doesn’t work for Westerners to come in with buckets of cash and tell Africans that they need to change their sexual behaviors, he says. Africans must take control of the prevention efforts in their own countries, the way Ugandans and some others have done.

One of the best things the West can do to assist prevention efforts in Africa, Halperin says, is to understand and accept the differences in African sexual culture—and when homegrown prevention efforts spring up, to at least stay out of their way.

Daniel Halperin is an adjunct associate professor of health behavior and health education in Carolina’s Gillings School of Global Public Health. Craig Timberg is the deputy national security editor at the Washington Post. Find out more about Tinderbox at