As it appears to be a phenomenon almost exclusive to the very young, expansion to the general population seems unlikely as that implies biological constraints.

As it appears to be a phenomenon almost exclusive to the very young, expansion to the general population seems unlikely as that implies biological constraints. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2869.2012.01022.x https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2869... Note the study itself is limited to under 20s but shows a clear age-related decline. My own anecdotal experience (which I agree, was awesome) confirms that.