Earlier quoted context omitted.
This is a fairly terrible take for a number of reasons, but let's assume good faith and indulge this. * What makes you think that, at any point, lower caste people had an on-average lower IQ? The same has been said for plenty of minorities that have been historically discriminated against, such as people of color and women, because opressors are in control of the narrative and see themselves as superior * What does "…
It is possible that higher casts selected for intelligence over the years. Since in India arranged marriage is the norm, parents can select for intelligence if that is a trait they care about. If there is a genetic portion of intelligence that can be selected for. Note the above uses words like "possible" and "if". I find it unlikely this is what was done. More likely - like every other society - they selected for po…
There is preliminary evidence from genetic sequencing that Indian castes have been highly endogamous for at least 3000 years.
India is a vast place with an enormous population, and there's resistance to continuing this research, for fairly obvious reasons. But continue it will, you can't un-sequence a genome after all. So we may yet see a robust answer to this sort of question.