When I read the Wealth of Nations I was struck by one of the passages where Smith basically says everyone under the age of 24 is worthless. That it doesn't matt

When I read the Wealth of Nations I was struck by one of the passages where Smith basically says everyone under the age of 24 is worthless. That it doesn't matter what they do, send them to university, or send them to travel. But that they won't be useful in commerce until they're older. I'd assumed at the time that the lack of maturity was a modern problem problem due to coddling, but it's apparently at least a problem for 300 years (for at least the caste likely to read his book). What struck me again later was finding out that 24 is the tipping point for the brain. That's about when the majority of brain matter is "gray" instead of "pink" (aka the process of myelination), which seems to be a biological rather than an environmental process. So this has likely been the case for a very long time (like 40,000 years or more).