I don`t think you understand that article. 
a drop in infant mortality rated would not skew the average lifespan statistic by that much, especially considering how many children people were having back then. the average was something like 8 kids in the 1800's and today it's 1.4. even with the infant mortality rate lowered they would still be having more than enough kids to even out the numbers back then.
any idiot can tell you food quality, air quality, working conditions, medical treatments, etc have improved DRASTICALLY since the 1800-1900's. it's still not great but it's significantly better.
i understood your bullshit no-supporting-studies-or-facts-cited article just fine. i just don't buy it.