In last Thursday’s GOP debate, Marco Rubio, Ted Cruz, Jeb Bush and Chris Christie managed to avoid mentioning their common proposal to “reform entitlements” by raising the Social Security retirement age from 67 to 70. That was probably a good idea. Their proposal only demonstrates their lack of understanding about the demographics of older Americans, especially the dramatic disparities in their life expectancy associated with education and race. Recent research on life expectancy indicates that their proposed change would effectively nullify Social Security for millions of Americans and sharply limit benefits for many millions more.. While many people in their 30s and 40s today can look forward to living into their 80s, the average life expectancy for the majority of Americans who do not hold a college degree hovers closer to 70, or the average life expectancy for all Americans in 1950.