How does income inequality in a population translate into mechanisms that affect a population's health? These publications, looking at primate populations, begin to tackle this question. Considered simply, chronic stress is produced within those in a hierarchy, with those towards the bottom having more stress. This has been studied most in non-human primates, and mechanisms there most likely apply to humans as well. Studies in primate populations range from those conducted by observation in the field, with occasional sampling of blood and measurement of parameters on anesthetized animals, as well as studies in captivity where many aspects of the environment are controlled and manipulated in the experimental design. While the material here focuses on the postulated effects of hierarchy or stress on populations to affect health, the usual risk factors for disease may also apply. 

1.  Keating DP, Hertzman C, eds. Developmental Health and the Wealth of Nations:  Social, biological and educational dynamics. New York: Guildford Press, 1999.

2. Sapolsky RM. Endocrinology alfresco: psychoendocrine studies of wild baboons. Recent 
     Progress in Hormone Research 1993; 48: 437-68.

3. Sapolsky RM. Poverty's remains. The Sciences (NY) 1991; 31: 8-10 

4. Shively CA, Clarkson TB. Social status and coronary artery atherosclerosis in female monkeys.
     Arteriosclerosis and Thrombosis 1994; 14: 721-6

5. Sapolsky RM. Stress, the aging brain, and mechanisms of neuron death. MIT Press, Cambridge 1992

6. Shively CA, Laird KL, Anton RF. The behavior and physiology of social stress and depression 
      in female cynomolgus monkeys. Biological Psychiatry 1997; 41: 871-82

7. Sapolsky RM, Share LJ. Rank-related differences in cardiovascular function among wild 
     baboons: role of sensitivity to Glucocorticoids. American Journal of Primatology. 1994; 32:
     261-75

8.  Erdal D, Whiten A. Egalitarianism and Machiavellian Intelligence in Human Evolution. In: Mellars P,
     Gibson K, ed.  Modelling the Early Human Mind.  Cambridge, UK: McDonald Institute for
     Archaeological Research, 1996: 139-160. McDonald Institute Monograph

9.Kristenson, M., K. Orth-GomZr, et al. (1998). "Attenuated Cortisol Response to a Standardized 
     Stress Test in Lithuanian Versus Swedish Men:  The LiVicordia Study.   International Journal of 
     Behavioral Medicine 5(1): 17-30.