I am not an evolutionary biologist so please excuse and correct any mistakes if you can. Lets assume there are some physical differences between the castes. These differences would have been brought into existence because at some point the respective populations were isolated and living under different sets of evolutionary pressures. If, over time, you remove physical isolation but replace it with cultural taboos against inter-breeding then the effect of these ancestral pressures can be preserved. Does that make sense?

It seems to me the real issue here is our inability to reckon with the fact that IQ is just another adaptation. If we were talking about a less central trait, say hair color, the down votes, insults and the flagging of the post would seem ridiculous, even though the exact same reasoning would apply,

It could work if smart people from lower casts were moved to higher casts and stupid people from higher casts were moved to lower casts. Ideally children would have to be cast-less and then at some age (before reproductive age) were promoted to one of the casts according to some intellectual test. And breeding would be allowed only between species of the same cast.

If I'm not mistaken, Indian casts do not work this way, so I don't think that it's possible to select anything.

I'm not even sure that intellect is affected by genes.

Of course this is all eugenics and considered inappropriate even to discuss in west.

It might work if intelligence wasn't important for members of lower castes but was for higher castes, perhaps due to the nature of their culture or work. Then low castes wouldn't select for intelligence but high castes would. Not saying that's what actually happened but it shows that selective pressure could still exist without inter-caste mobility.

Stop this nonsense about topics being inappropriate to discuss unless you're a nun. Nobody has a cultural taboo about discussing dog breeding or evolution of other traits. Just race and intelligence is taboo because people have been indoctrinated to believe that low intelligence marks you as an inescapably undeserving or a "bad" person. If you broaden your mind and stop treating intelligence as such an important aspect of life, then it won't be so taboo.

>t might work if intelligence wasn't important for members of lower castes but was for higher castes, perhaps due to the nature of their culture or work. Then low castes wouldn't select for intelligence but high castes would. Not saying that's what actually happened but it shows that selective pressure could still exist without inter-caste mobility.

This makes absolutely no sense, unless the "not so smart" were not considered for reproduction or were eliminated. How are you selecting for IQ if the only thing you need to get married is to be in that cast? Arranged marriages don't help with natural selection; you just need to exist in the right family.

It really depends how things work over there. Castes are associated with jobs and I have seen some articles that some 'teacher' cast has higher intelligence, just like eg ashkenazi jews. It could be that being pretty unsuccesful at your caste-assigned job would have left you unemployed and thus not being able to support a family, thus not being able to marry. thats obviously speculation, of course.

It does not make any sense, no matter how you look at it.

Sure, you can see those "articles", but don't forget that those are going to be based on IQ tests, and those are correlated with intelligence and... wait for it... education.

If I was of the superior caste that's what I would try to make people believe: "we are superior, and we are here because we are smarter than you. Best of luck in your next life".

Someone with a high iq will be more capable of following a certain education path. So education and iq being correlated usually means the iq measure is working as intended. If however going to a great school improves your iq that proves the specific iq measure used is flawed (as its supposed to measure innate intelligence, not education). As for the other part, I agree my line of reasoning is rather unsympathetic.

Here's the problem you're not getting here.

Lets say tomorrow the society (lets presume all of them are WASPs) decides to divide themselves between people whose name start with a J (the most common letter for names in US, like James, John, Jennifer, Jessica, Jesse etc) and non-Js. And this J group declares themselves as the 'upper caste' with Js only marrying with Js and non-Js only among non-Js. Also they even live in physical isolation from each other.

Two thousand years later, which group will have higher IQ?

The answer is, you can't tell. Whatever is the starting group IQ of these two groups is, that's exactly what it would be for the latter.

Same goes with your theory about upper castes having higher IQ. Now the place where you might be right is (not that you realize that), if there is an IQ test available only to the J's, and they prefer to marry to the highest IQ person willing to marry them, but the other caste does not have this test available. Now, over generations, one group will be selecting for the IQ but the other won't be able to.

The 'IQ test' could be education (and jobs which require education like priesthood) which was generally only available or restricted to the Brahmins (so not 'all' higher castes). The more 'Vedas' you memorized (which weren't written down for a long period), the more esteemed scholar you were, this is why the have last names like Dvivedi or Dubey ('a scholar who memorized 2 vedas') or Trivedi (a scholar who memorized 3 vedas) or Chaturvedi or Chobey (a scholar who memorized all 4 vedas).

Here, you COULD see that if Brahmins are only allowed to be educated, and IFF they are choosing for those who show a 'higher score' in terms of IQ, then there can be an optimization for IQ.

A control group would be a higher caste which isn't optimizing for education or any other proxy for IQ (like being in successful business is a kind of IQ test, not as strong of an IQ test as being able to memorize vedas, but still, it is).

You're trying to compress a bunch of dimensions all into one explanation of "IQ", and you're assuming a lot of things here, such as physical isolation would cause divergence in IQ; that divergence in IQ would also cause later societal hierarchical advantages (over natural resources, physical power, or other non-IQ circumstances or differences); and that later removal of the physical separation and original selection pressures would continue to select for IQ in the subgroup. Maybe once your elites get entrenched, they select for other attributes like physical ones instead. I don't see a lot of societies out there where marriages are formed based on pure intellect.

The assumption you're making that you haven't substantiated is that higher (as in socially-more-powerful) castes have higher IQs.

(There are a number of other unsubstantiated assumptions beyond that, including that the difference in IQ is enough to explain the observed effect, that the variance in the distribution of IQs in each population is pretty close to zero, that castes started out as physically-isolated populations with distinct IQs, etc., but let's start with that one.)

That doesn't even make sense. The artificial pressure of "is this person's family from a caste that is comparable enough to our own that we can arrange for our children to marry" is taking priority over any other selection criteria. Whether you're right or wrong about the genetics of IQ is irrelevant -- you're fighting way too hard without realizing you're not even in that arena.