John - Thank you for your comment. You have an excellent question and one that is subject to a lot of debate. The Research Foundation of CFA Institute published a literature review on emerging market investing. http://www.cfapubs.org/doi/abs/10.2470/rflr.v1.n1.4150
You can also visit our website (www.cfainstitute.org) or publications site (www.cfapubs.org) and do some searches.