We are all, I think, aware of arsenic exposure upon early Americans from Albuquerque to Chile. This led to the survival of the AS3MT mutation, expressed in the liver. It turns out that the Old World had toxic mineral exposure too. In our case: lead (plumbum; -208 mostly).
These early hominins had to have ingested the lead somehow, because it's right there in the remains. And we can't blame modern contamination. The bones are dead, dude; if there was ambient lead it should coat only the outside.
The claim is that lead salts had dissolved into cave water. I'd have thought that sedimentary caves like limestones and sandstones go more to calcium and silicon. But some caves are volcanic, or are simply ... downstream of the mountains. It gets worse: lead acetates hit the "sweet" tastebuds. So people - meaning, anthropithecenes - would actively seek out the lead-infused "mineral" water against pure tasteless water.
Eventually, back in Africa, our shared ancestors evolved brain defences against lead. Which, in Roman times, evolved brains as could tell that lead should not be ingested; and in modern times, that could tell the rich not to blow it into our environment.
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