Life expectancy grows when there are more primary care physicians in the field, yet their numbers are shrinking as medical students saddled with debt turn to more lucrative fields, according to a study led by researchers at Stanford and Harvard.

New research shows us just how important primary care physicians are in prolonging our lives. Every 10 additional primary care physicians per 100,000 people in the United States was associated with a 51.5-day increase in life expectancy during the decade from 2005 to 2015, according to a study led by researchers at the Stanford University School of Medicine and Harvard Medical School.