The Lead Poisoning Thesis

Some research is startling, and some research confirms what we already guessed or assumed, but there’s some research which falls between these categories: research which reveals things that should have been obvious, if we’d been thinking about it clearly, or asked the right questions earlier. Siniawer’s argument about the consistency of violence in Imperial Japanese politics falls into that category, as does the new transnational migration scholarship that sees migration as a multi-directional, multi-generational process. I’m sure you have other examples

In the same vein, there’s new archaelogical research from Kitakyushu, announced on LiveScience with the headline “Lead Poisoning in Samurai Kids Linked to Mom’s Makeup.” A study of 70 sets of samurai class remains included several of children:

Children under age 3 were the worst off, with a median level of 1,241 micrograms of lead per gram of dry bone. That’s more than 120 times the level thought to cause neurological and behavioral problems today and as much as 50 times higher than levels the team found in samurai adults. Older kids’ levels were lower, but still very high.

What’s more, five of the children had unusual bone enlargements, and X-rays revealed banding that only turns up in children with at least 70 micrograms of lead per deciliter of blood.

The study also found, confirming earlier findings, that samurai women had higher levels of lead exposure than men by a very high degree, suggesting that the lead-based makeup of upper-class women was the primary environmental source, and that the women were exposing the children to lead both through contact and through breast milk. Obviously, there’s a slight sample bias in the study, as the highest levels of lead exposure seem to have resulted in the youngest deaths, and children who were not heavily exposed seem to have survived longer. Other studies of adult remains suggest “that samurai and merchants living in Kokura had much higher lead levels in their bones than did farmers and fishermen living nearby” which may be a result of childhood exposure or may be the result of continued contact.¹ This is interesting, no question, and I’ve never heard anyone actually suggest before that the use of lead — which we routinely point out is quite unhealthy for the women involved — would almost certainly have effects on children as well.

The article then does something which drives me a bit crazy, and illustrates how zombie ideas work, not to mention the journalistic tendency to escalate findings into “smoking gun” monocausal historical narratives. The very next sentence, after the quotation above, is “They also point to individual shoguns known to have suffered from intellectual and health problems associated with lead poisoning.”

In case you don’t get it, there’s a direct invocation of the Lead Poisoning Fall of Rome hypothesis:

It wouldn’t be the first time lead poisoning rang in the end of an era. Others have suggested that “plumbism” among the Roman elite — whose fancy food and wine was laced with lead leached from cooking equipment — contributed to the fall of the Roman Empire.

This is an old zombie chestnut, one that has been slain and risen again and been slain again many times.² I particularly like the “others have suggested” phrase, a journalistic standby for taking a position in a debate, especially a false position, without having to take responsibility for the error.

The assumption that shogunal intelligence and temperment — the aspects most affected by lead toxicity — were the cause of the end of the Tokugawa regime is clearly a gross misreading of the history. There are structural issues which are quite independent of personalities, issues which often have their origins in the earliest — and least likely to be lead-poisoned — policies of the bakuhan system. The archeologists seem to be arguing in this direction, though:

Nakashima and his team think a ruling class addled by lead poisoning may have contributed to political instability, and ultimately to the collapse of the seven-century-old shogun system in 1867, when power shifted cataclysmically from the shogun to the emperor, and life in Japan changed for good.

I don’t see how this can possibly stand up to serious scrutiny: the main problem of the Tokugawa regime wasn’t constant political instability, but excessive political stability in the face of a need for sustained reform. Instability in the bakumatsu comes from a clash of intelligent capable leaders with strong personalities and dramatically different ideas about core issues, differences that are largely ideological, and entirely comprehensible in the long-term context of Tokugawa ideologies. It doesn’t require an epidemic of induced cognitive dysfunction to explain the behavior of the samurai or merchant classes of late Tokugawa Japan.³ And “contributing factor” is such weak sauce, a phrase which is too-often used to describe plausible theories lacking evidentiary support, when it should really be limited to aspects that are documented but whose degree of influence are somehow indeterminate.⁴

I understand the desire to inflate findings, to make one’s own research the causal center of events, to see through one lens. And I understand how that’s exacerbated by journalistic writing, which wants to draw attention to itself. But perpetuating zombie errors and the stereotype of the monocausal smoking gun method of historical storytelling is inexcusable, no matter how interesting the actual findings.

1. as an aside, I don’t recall ever reading that adult males outside of the theater trades used makeup routinely, as this article seems to suggest.  ↩

2. Wikipedia currently hedges, but seems to come down on the side that the hypothesis is plausible. As I tell my students, “plausible” does not imply “true” in historical argumentation.  ↩

3. the ee ja nai ka religious movements, on the other hand, and the rising tide of peasant protests, are too episodic and entirely based in the wrong classes.  ↩

4. as they often are in historical hindsight, once we eschew monocausal simplicity  ↩