Why is India so low in the Pisa rankings?

Tyler Cowen:

That is a request from J. and here is one recent story, with much more at the link:

A global study of learning standards in 74 countries has ranked India all but at the bottom, sounding a wake-up call for the country’s education system. China came out on top.

On this question, you can read a short Steve Sailer post, with comments attached. Here are my (contrasting) observations:
1. A big chunk of India is still at the margin where malnutrition and malaria and other negatives matter for IQ. Indian poverty is the most brutal I have seen, anywhere, including my two trips to sub-Saharan Africa or in my five trips to Haiti. I don’t know if Pisa is testing those particular individuals, but it still doesn’t bode well for the broader distribution, if only through parental effects.