When my wife and I wrote about my old schoolmates who had died from “deaths of despair,” the reaction was sometimes ugly.

“They killed themselves,” scoffed Jonathan from St. Louis, Mo., in the reader comments. “It was self-inflicted.”

Ajax in Georgia was even harsher: “Natural selection weeding out those less fit for survival.”

Our essay, drawn from our new book, “Tightrope,” explored the disintegration of America’s working class through the kids on my old No. 6 school bus in Yamhill, Ore., particularly my neighbors the Knapps. The five Knapp kids were smart and talented, but Farlan died after years of drug and alcohol abuse, Zealan died in a house fire while passed out drunk, Nathan blew himself up cooking meth, Rogena died of hepatitis after drug use, and Keylan survived partly because he had spent 13 years in the Oregon State Penitentiary.

Working-class men and women like them, of every shade, increasingly are dying of “deaths of despair” — from drugs, alcohol and suicide. That’s why life expectancy in the United States, for the first time in a century, has declined for three years in a row.