The risks to health faced by Americans long ago are different from those we face today. Some of the things that once killed many people (like poor sanitation) now kill many fewer. On the other hand, we now face new risks (like death from auto accidents) that didn’t exist a century ago.
The causal pathways from social determinants of health to health outcomes can be numerous and complex. Though some factors (like smoking) are directly related to health, others (like education or income) relate to health in a variety of indirect ways.