This week's Science is focusing on the effects, causes, and future of inequality, and it's well worth the read if you have access (oh the irony...).
Specific articles that caught my eye:
The ancient roots of the 1%: Mankind's history of inequality, which extends pretty far back. While inequality was traditionally thought to arise with agriculture, evidence now also points to it existing amongst hunter-gatherers. Those with access to richer lands, hoard and protect those resources.
Can disparities be deadly?: The negative health effects of inequality may not be just due to income and access to health care. Even amongst those with equal access to care, those with a lower social status have poorer health. An obvious reason can be stress, although one interesting interpretation is that the relationship is reversed: those in poorer health end up with lower status.
The intergenerational transmission of inequality: Maternal disadvantage and health at birth: A review of studies on income inequality and effect on newborn health. Economically disadvantaged mothers give birth to lower weight newborns, and they cover various factors that can contribute to this such as access to health care, poor diet, and legal/illegal drug use. Inequality continues to breed inequality.