Give a comprehensive response (minimum of 300 words) to the following questions:
1) Where do health differences among social groups originate, if we trace them back to their deepest roots;
2) What pathways lead from root causes to the stark differences in health status observed at the population level;
3) In light of the answers to the first two questions, where and how should we intervene to reduce health inequalities?
Formatting: Cite references where appropriate and provide a reference list for all references cited.