If a 10-year-old boy in Benin, in West Africa, wants to describe someone he doesn’t trust, he’s likely to use one of these two roughly translated phrases: “He will sell you and enjoy it” or “He can make you disappear.”

Such phrases are not uncommon in the languages of West Africa, which for four centuries was the epicenter of the continent’s slave trade, and their presence in contemporary speech poignantly suggests that slavery’s legacy lingers on in profound ways.

That’s the premise of a fascinating new study by economists Nathan Nunn and Leonard Wantchekon on the slave trade and the origins of social mistrust in Africa.

For decades, sociologists and economists have been homing in on the importance of trust in creating a properly functioning democracy and a stable economy. Simply put, societies in which trust is high have better governments, more open markets and less corruption. It makes sense really. All kinds of cooperation – be it political or financial – require mutual trust and predictability.

In commerce, the absence of trust can not only scare investors out of the market, it can raise the everyday costs of doing business. Businesspeople in high-trust societies spend much less time and money trying to protect their interests and are more likely to take risks that lead to innovation. Austrian economist Joseph Schumpeter once noted that the distinguishing feature of capitalism is the financing of innovation with borrowed money. If that’s true, then credit is the root not only of economic development but of all social progress. Also, in the words of British economist Walter Bagehot, it’s “the disposition of one man to trust another.”

Using both contemporary household surveys and historical data on slave shipments, Nunn’s and Wantchekon’s study found that people whose ancestors were heavily threatened by the slave trade a century or more ago still exhibit less trust in neighbors, family members and local authorities today. Combating this low level of trust, the authors argue, is key to the region’s economic development.

What’s intriguing about their findings is that the mistrust is directed not just at the outsiders who bought and exported slaves. That’s because, by the end of the slave trade, it was not uncommon for individuals to be sold into slavery by friends or family members. The authors suggest that the profound and insidious mistrust this engendered was passed on from generation to generation as a means of protection. Parents would incorporate a distrust of others into the set of values they sought to instill in their offspring. Over time, the response to the trauma of slavery became part of the local culture.

Most social-mistrust studies focus on how members of one group might view members of another. We tend to assume that familiarity breeds trust, and dissimilarity, the opposite. This study, however, focuses our attention on the equally important phenomenon of intra-group mistrust.

“I think this shows that the idea that people who know each other and share the same language and experiences automatically trust each other is not true,” said Wantchekon, who is from Benin but now teaches economics and political science at New York University. “When we talk of Africa, in particular, we talk of all these groups that can’t get along. But there are times when the level of mistrust for your own people can be just as bad if not worse than that for other people.”

Unlike other ethnic groups, say Jews or Armenians, who have built communal solidarity in the wake of oppression at the hands of others, many African ethnic groups remain fragmented to this day because of the insidious nature of slavery.

I asked Wantchekon whether his approach to West African culture wasn’t a bit like psychoanalysis, and he didn’t deny it. He and his colleague are trying to figure out how collective historical trauma has created patterns of cultural behavior – neuroses, if you will – that hinder the economic and social well-being of contemporary West Africans.

Unlike so many similar conversations of slavery in the United States, these scholars’ interest isn’t in blame, retribution or reparations but in “correcting” cultural behaviors that are harming societies.

So what’s the first stage in healing? The media and early childhood education, Wantchekon suggests, could help eradicate mistrustful preconceptions.

“We need to talk,” he said, like a good shrink. “Talk shows could play a big role. We need to understand that our reasons to distrust no longer have a basis in reality. We need to show people that all this distrust is nonsense.”