Larry Harrison watches with alarm as noisy Brazilians invade his peaceful island community of Martha's Vineyard in Massachusetts, creating mistrust between old and new residents.
"We are in the United States, not Brazil," the college professor recently shouted at a group of immigrants who he said were among a new crowd who blasted loud music "whenever and wherever."
"They come from a culture that is inconsiderate of others — captured in the Spanish expression Que viva yo or 'Long live I,'" said Harrison, director of the Cultural Change Institute at the Fletcher School at Tufts University.
"It's a human nature problem," he said. "We are not comfortable with people who look, act and speak differently. It contributes to loss of social capital."
The term "social capital" was popularized in 2000 by Harvard University sociologist Robert Putnam, whose best-selling book "Bowling Alone: The Collapse and Revival of American Community" noted a drop in the social networks that allow civic engagement to thrive.
But in another study, Putnam found that as the diversity within a community rises, the number of people in that community who vote, volunteer or give to charity falls.
The politically incorrect findings have been used as ammunition in the ratcheted-up immigration debate.
Several conservative groups have taken a "told-you-so" stance and jumped on his research to seal their own arguments against diversity.
The notion that immigration strengthens society has been the backbone of the American psyche since the term "melting pot" was coined at the turn of the 19th century.
After civil rights legislation in the 1960s, racial diversity was considered irrefutably good for America.
On the face of it, Putnam's study turns that notion on its head.
"There are big payoffs with immigration, but in the short run our research does show none of us is comfortable with diversity, and we all hunker down like a turtle," Putnam told ABCNEWS.com.
In 2000, Putnam interviewed 30,000 people from 41 communities — small and large, rich and poor. Residents were sorted among black, white, Hispanic and Asian. They were asked how much they trusted their neighbors and questioned about civic attitudes, practices and friendships.
The anti-immigration commotion began in June, when it was published by the Scandinavian Public Studies journal after Putnam received a prize for his work.
"Putnam's implications are ominous," wrote conservative blogger Pat Buchanan. "We are talking here about nothing less than the survival of our country."
"If he's right, heavy immigration will inflict social deterioration for decades to come, harming immigrants as well as the native-born," wrote John Leo, editor of the conservative Manhattan Institute's online magazine.
Even David Duke, the self-described "white nationalist" and former grand wizard of the Ku Klux Klan, cites Putnam's research on his Web site.
"I've taken a ton of flak," said Putnam, who even received a letter addressed, "Dear intellectual turd."
Putnam was accused of suppressing the study because it contradicted his liberal leanings, even though Harvard released his findings in 2001, and raw data was made publicly available.
"It's wrong to say we hid the data," said Putnam. "We shouted it from the rooftops."