"Almost everyone of the Civil War generation was plagued by life-sapping illnesses, suffering for decades. And these were not some unusual subset of American men — 65 percent of the male population ages 18 to 25 signed up to serve in the Union Army. "They presumably thought they were fit enough to serve," Dr. Fogel said.
Even teenagers were ill. Eighty percent of the male population ages 16 to 19 tried to sign up for the Union Army in 1861, but one out of six was rejected because he was deemed disabled.
And the Union Army was not very picky. "Incontinence of urine alone is not grounds for dismissal," said Dora Costa, an M.I.T. economist who works with Dr. Fogel, quoting from the regulations. A man who was blind in his right eye was disqualified from serving because that was his musket eye. But, Dr. Costa said, "blindness in the left eye was O.K."
...Men living in the Civil War era had an average height of 5-foot-7 and weighed an average of 147 pounds. That translates into a body mass index of 23, well within the range deemed "normal." Today, men average 5-foot-9½ and weigh an average of 191 pounds, giving them an average body mass index of 28.2, overweight and edging toward obesity.
Those changes, along with the great improvements in general health and life expectancy in recent years, intrigued Dr. Costa. Common chronic diseases — respiratory problems, valvular heart disease, arteriosclerosis, and joint and back problems — have been declining by about 0.7 percent a year since the turn of the 20th century. And when they do occur, they emerge at older ages and are less severe.
The reasons, she and others are finding, seem to have a lot to do with conditions early in life. Poor nutrition in early years is associated with short stature and lifelong ill health, and until recently, food was expensive in the United States and Europe.
Dr. Fogel and Dr. Costa looked at data on height and body mass index among Union Army veterans who were 65 and older in 1910 and veterans of World War II who were that age in the 1980’s. Their data relating size to health led them to a prediction: the World War II veterans should have had 35 percent less chronic disease than the Union Army veterans. That, they said, is exactly what happened.
They also found that diseases early in life left people predisposed to chronic illnesses when they grew older.
"Suppose you were a survivor of typhoid or tuberculosis," Dr. Fogel said. "What would that do to aging?" It turned out, he said, that the number of chronic illnesses at age 50 was much higher in that group. "Something is being undermined," he said. "Even the cancer rates were higher. Ye gods. We never would have suspected that."
Men who had respiratory infections or measles tended to develop chronic lung disease decades later. Malaria often led to arthritis. Men who survived rheumatic fever later developed diseased heart valves."
(So Big and Healthy Grandpa Wouldn’t Even Know You - New York Times)