>Given the portion of people in the third world who live incredibly short lives

Third world countries have lower average life expectancies because infant mortality is higher; many more children die before age 5. But the life expectancy at age 5 in third world countries is not much different to the life expectancy at age 5 in America.

Maybe incredibly low is an overstatement, but Nigeria for example could easily add another 18 years of life expectancy (to match that of white Australians) at age 15 if their economic issues were resolved.