I'm guessing you are not an expert in human behavior. I'm not either. Your last sentence though is an example of the sort of sloppy thinking that kills your d

I'm guessing you are not an expert in human behavior. I'm not either. Your last sentence though is an example of the sort of sloppy thinking that kills your desire to read further. You say, "different populations may have evolved...". You don't present any evidence for this. You just state it as a possibility. It might be the case that god causes the delay in Tibetans. Is it the responsibility of the article to counter this possibility? The article gives a credible reason for the delay in Tibetans and if the reason is correct it reinforces the idea that it is cultural. I assume the researchers know a lot more about the topic than I do. In my experience if there is a possible objection to a conclusion researchers have made that I can think of when thinking about the topic for a few minutes then I'm the one who is almost certainly wrong.