After my post last week about the pre-print paper calling the “Blue Zones” (aka areas with unusual longevity) in to question, an anonymous commenter stopped by to drop the link to the Blue Zones groups response. I thought their response was rather formidable, so I wanted to give it a whole post. They had three major points, all of which I was gratified to see I had raised in my initial read through:

1. Being designated as a Blue Zone is no small matter, and they have well published criteria. Some places that come to their attention are invalidated. There also are some pretty extensive papers published on how they validated each of the existing 5 regions, which they linked to. Sardinia here, here and here. Okinawa had a paper written on it literally called “They really are that old: a validation study of centenarian prevalence in Okinawa“. Dr Poulain (who did much of the age validation for Sardinia) wrote a paper 10 years ago called “On the age validation of supercentenarians” where he points out that the first concerns about validating supercentenarian ages were raised in 1873. This book has more information about their methods, but notably starts with mentioning 5 regions they were unable to certify. Basically they responded with one big link dump saying “yeah, we thought of that too”. From what I can tell there actually is some really fascinating work being done here, which was very cool to read about. In every place they not only looked at individuals records, crosschecking them with numerous sources, doing personal interviews with people and their families, and then calculating overall population metrics to looks for evidence of fraud. In Okinawa, they mention asking people about the animal for the year of their birth, something people would be unlikely to forget or want to change. It seems pretty thorough to my eye, but I was also struck that none of the papers above were included as references in the original paper. I have no idea if he knew about them or not, but given that he made statements like “these findings raise serious questions about the validity of an extensive body of research based on the remarkable reported ages of populations and individuals.”, it seems like a gap not to include work that had been done.
2. Supercentenarians are not the focus of the Blue Zones. Again, they publish their criteria, and this is not a focal point. They have focused much more heavily on reaching 90 or 100, particularly with limited chronic disease. As I was scanning through the papers they linked to, I noticed an interesting anecdote about an Okinawan man who for a time was thought to have lived to 120. After he got in the Guinness book of world records, it came out that he had likely been given the name of an older brother who died, and thus was actually “only” 105. This is interesting because it’s a case where his age is fraudulent, but the change wouldn’t impact the “Blue Zone” status.
3. Relative poverty could be correlated with old age. I raised this point in my initial post, and I was glad to see they echoed it here. Again, most of the way modernity raises life expectancy is by eliminating child mortality and decreasing accidents or repairing congenital defects. Those are the things that will kill you under 55. Over 55, it’s a whole new set of issues.

Now I want to be clear, no one has questioned the fundamental mathematical findings of the paper that in the US the supercentenarian records are probably shaky before birth registration. What’s being questioned is if that finding it’s generalizable to specific areas that have been heavily studied. This is important because in the US “old age” type benefits kick in at 65 and there is no level after that. So basically a random 94 year old claiming to be 111 might get a social bump out of the whole thing, but none of the type of benefits that might have caused people to really look in to it. Once we start getting to things like Blue Zones or international attention though, there’s actually whole groups dedicated to looking in to things. One person faking their age won’t cause much of an issue, but if your claim is that a dozen people in one town are faking their ages, that’s going to start to mess up population curves and show other anomalies. The poorness of the regions actually helps with this case as well. If you’re talking to people in relative poverty with high illiteracy, it’s hard to argue that they could have somehow been criminal masterminds in their forgeries. One or two people can get away with things, but a group deception can be much harder.

I’m still going to keep an eye on this paper, and my guess is it will be published somewhere with some of the suggestions of generalizability toned down, and more references to previous work at validating ages added.