this is a true story but years ago, a group of scientists in India wanted to find out who in the world had the smallest brains as a population. Unfortunately, they came to the conclusion that the people of India on average, have the smallest brains of anyone in the world. I think it’s most likely because so many of them are vegetarian and they don’t get enough animal protein. Your brain is mostly made up of fat so it actually makes sense. There’s nothing genetically wrong with them, it’s just their nutrition is horrible. As soon as they started eating meat, I’m sure they would probably come up to the world average in a few generations. But I always thought that was interesting.
On average you could be correct. However. Their meat eating Pakistani cousins test LOWER on IQ than the Indians. So brain volume isnt IQ and isn’t solely dietary. It is IQ that drives socioeconomic outcomes, not brain size.
Also correct for the Indians’ lower body weight. I do believe though that the average Indian is so poor and his diet so lacking in animal products that health and brain size are absolutely affected