Lead in ancient human bones and its relevance to historical developments of social problems with lead.

Concentrations of metabolic lead in buried ancient bones are obscured by replacement of calcium in apatite by excessive amounts of soil moisture Pb. Concentrations of metabolic barium in bones are affected in a similar way. Added soil Pb and Ba, expressed as log(Pb/Ca) versus log(Ba/Ca) among various bones at a given burial site, are positively covariant, with about 5-fold more soil Pb added for each unit of added soil Ba. The typical natural metabolic Ba/Ca ratio in contemporary people can be measured unambiguously because it as unaffected by industrial pollution. It applies to ancient people because it has not changed historically. The intercept of the covariance curve for buried bones of a given ancient population at the known metabolic Ba/Ca ratio indexes the corresponding metabolic Pb/Ca ratio in bones of that population. Lead levels which prevailed in Romans appear to have been similar to those in contemporary people, which are approximately 1000-fold above natural levels in humans determined by this method in ancient Peruvians. This indicates that studies of natural biochemical reactions in cells free of industrial Pb should be made, because most present biochemical knowledge is founded on data obtained from systems polluted with Pb 1000 to 100000-fold above natural levels. The 5000 year history of smelting Pb by humans indicates that a system of education fostered by genetically common lower brain center functions operated on hundreds of successive generations in a context of cultural changes invoked by feedback from developments in engineering technologies to give rise to the difference between present typical and prehistoric natural levels of Pb in humans. Archaeological and anthropological studies of early developments in writing, music and metallurgy by ancient Peruvians and Persian peoples should be combined with PET-scan studies of their descendants to discover if, as preliminary archaeological data suggest, the two ancient populations differed on a genetic basis in higher brain functions, yet are indistinguishable as metallurgical engineers. This would demonstrate that higher centers of the human brain did not exercise guiding control, through hundreds of generations, over those developments of engineering technologies which resulted in the extreme pollution of the earth's biosphere with poisonous Pb.