Indonesian SODIS users (picture: SODIS Eawag)
SODIS is a cheap method of disinfecting water by putting it in the sun. Like many things, it works better in physics than society, where its effects were not significant, according to a study in PLoS medicine recently. The technical barrier is that people don’t do it much. About thirty two percent of participants in the study used the system on a given day. If you’re familiar with how little things work in reality, this is still surprising. Cheaply disinfecting water seems like it would be a hit with poor people whose children get diarrhea all the time and regularly die. Rural Bolivia, where the study was done, is a good candidate. The children studied usually get diarrhoea four times a year, which causes about fifteen percent of deaths of children under five. For the poorest quintile in Bolivia the under five death rate is about one in ten of those born alive.
The leader of the study, Daniel Mausezahl, suspects a big reason for this is that lining up water bottles on your roof shows your neighbors that you aren’t rich enough to have more expensive methods of disinfecting water. It’s hard to see from a distance the difference between chlorination and coliform-infested jerry cans, so drinking excrement can make you look better than drinking cheap clean water.
Fascinating as signaling explanations are, this seems incredible. Having live descendents is even more evolutionarily handy than impressing associates. What other explanations could there be? Perhaps adults are skeptical about effectiveness? There is apparently good evidence it works though, and there were intensive promotional campaigns during the study. What’s more, lack of evidence doesn’t usually stop humans investing in just about anything that isn’t obviously lethal in the absence of effective means to control their wellbeing. And parents are known for obsessive interest in their children’s safety. What’s going on?
Meteuphoric 
My guess is: social stigma is now and real, while harm to the children is not a concern because it’s in the future and might not even happen.
Loss of status is certain – loss of life is less likely.
Perhaps certainty bias: http://www.scientificamerican.com/article.cfm?id=the-certainty-bias
People not admitting the risk of death due to fear? (As in feardie.pdf)
http://hanson.gmu.edu/feardie.pdf for those who aren’t working under the assumption that the default location for interesting things is Robin Hanson’s home page.
Fascinating! It seems we just do not move into a calculating mode when health is concerned.
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There’s a distribution of meticulousness in the human population. One third are fastidious (and have sufficient resources): they use chlorination. One third are laid back: they do nothing. The remainder use this system.
It seems to me that participating in this scheme requires a certain temperament.
agree it’s temperament — there’s all sorts of things people can do all the time that would greatly increase survival rates. most people aren’t great at paying attention to detail, or caring, or believing things like this work, and the poor people who might benefit from this also likely have a large number of other things to deal with that seem equally if not more important. put simply, no mystery at all.
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If humans have always had healers/magic men telling them to do apparently nonsensical things then they might be evolved to agree and ignore those recommendations. Much more likely, they simply haven’t evolved a tendency to consider abstract probabilistic and long-term consequences, either memetically or genetically.
What were the explanations offered by the people being studied? It seems far too convenient to assume they’re merely stupid.
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I have to admit that I subjectively feel there’s something implausible about the effectiveness of ‘disinfect water by leaving it in bottles in the sunlight!’ Maybe one problem with the study is that these Peruvians don’t ‘know to be true’ what someone told them about the treatment method.
” The leader of the study, Daniel Mausezahl, suspects a big reason for this is that lining up water bottles on your roof shows your neighbors that you aren’t rich enough to have more expensive methods of disinfecting water. ”
He’s there and I’m not, so maybe. BUT I would say, based on my experience in the third world, that an astonishingly large fraction of society seems pretty uninterested in anything that represents a change, regardless of the value of that change.
In Myanmar, driving without a seatbelt is not illegal. And so, not only does everyone drive without a seatbelt but they actively work against seatbelts. Most modern cars beep or otherwise complain if the seatbelts are not buckled — so the car owners deliberately buy meath “sheaths” to buckle onto the seatbelt to make it shut up.
I saw similar horrific things everywhere I looked — for example welders operating without a helmet, even though the helmet was sitting next to them. Or people clambering around scaffolding without hard hats or safety harnesses.
Outsiders like to claim this is because awful Capitalist Management doesn’t care if the workers live or die. I saw no evidence of this; the impression I get is that management damn well wishes workers would use the safety equipment provided, and that it’s workers who refuse to do so when they can get away with it. (Again I refer you to the seatbelts.)
And it’s not just the third world. Look at how bikers have fought tooth and nail against helmets in the US. (And, of course, American Football…)
In other words, I think the rational or economic model of how society improves (insofar as it improves safety), is utterly decoupled from reality. The REAL model seems to be that a small do-gooder fraction of society manages to get a law passed, enforcement of that law creates a new norm, and eventually that new norm becomes the default that’s followed by the 95% lazy who just do whatever is some combination of “easiest” and “the way we’ve always done things”. For this process to work you need
– do-gooders able to get the law on the books
– enforcement of the law
Both of these don’t exist in poorer countries, and even getting the first has little effect on the second.
Meaning that, getting back to disinfected water, giving people the option of “do the smart thing” vs “do the traditional thing”, you’re never going to get much progress.
Compare to the situation in the US wrt say binge drinking on campus. This is clearly problematic along multiple dimensions, yet “it’s the way things are done” and so it continues, even among those many participants who say that they wish it would stop. Simply knowing the smart thing is not enough, some combination of inertia (doing what you have always done) and social pressure (doing what everyone else is doing) keeps things going. The only way to stop it would appear to be criminalization followed by aggressive persistent law enforcement, so as to establish a new norm.