Lower intelligence would likely surface as hedonistic behavior which is probably hard to distinguish from decadence. Decadence and hedonism were constantly being complained about long before the eventual fall.
You're going to have to explain your point to me, or perhaps you misunderstood my own.
My point is that while it may have been unclear to the Romans as to the cause of changes in behavior they did notice a change and did complain about it a lot. I accept the premise that lead poisoning leads to lower intelligence.
What we know now is that lead’s effects are more pronounced as developmental issues. A little lead exposure as a child can lead to a violent temper. So once children were not born into a low grade cloud of lead contamination, they were set up for fewer mood disturbances as teenagers and young adults. Feeling like violence is your best avenue for conflict resolution leads to crime. So the change wasn’t over night, it was over 20 years.
I expect that whatever effect was going on in Rome if there was one, which seems to be up for debate, counted on pregnant women exposed to lead via alcohol and acidic foods, neither of which young children would normally encounter. Meanwhile lead dust from exhaust got -everywhere-, and paint a lot of places.
I still think you are agreeing with the implied and later stated accepted premise that there is a correlation and it’s not always obvious, I’m still unsure as to what it is you are trying to add.
> Violence in the US declined as children born around and after leaded gas was banned reached the average age of first offense
My pet hypothesis for the generation born after in the mid postwar era having been a general scourge on America is that we had a population boom amidst lead.
