This is a weekly summary, published each Thursday, of topics and ideas we think will be useful to anyone who wants to practice Personal Science, using science for personal reasons rather than as a job.

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Links worth reading

NEO.LIFE published some of our personal science-related gift ideas
ISB microbiome researcher Sean Gibbons wrote a Twitter thread about “healthy aging” and why it’s more complicated than it looks.
There are 378 fact-checking groups, up from 168 in 2016. But who fact-checks them?
Tim Friede taught himself how to develop immunity to snake bites. (and a step- by-step guide for how to do it yourself)

Is Diversity Good or Bad?

Bristle Health (which we discussed in Personal Science Week - 29 Sep 2022) added a new metric, diversity, to their oral microbiome test. Interestingly, on my morning and evening tests from a single day, the report concludes that my diversity is highest right after waking up, and apparently falls much lower throughout the day. If anything, I would have expected diversity to rise after a day spent breathing, eating, and interacting with the much more diverse external world. Why would this be?

Results from two tests in a single day. (Bristle Health)

The diversity section in our ebook Personal Science Guide to the Microbiome describes how these metrics are calculated, and concludes that many of our intuitions about diversity are misplaced. In general, you’d expect that having a bigger variety of microbes makes for a greater supply of options when/if something goes wrong. But this depends on what goes wrong. Diversity is neither “good” nor “bad” on its own. Like everything else with the microbiome, it depends…

Learning from Zika

Long before COVID, for a brief period during 2015, the news was full of dire warnings about a new virus that was especially scary because of one awful side effect: microcephaly, deformed heads of babies born to women infected while pregnant. President Obama, consulting with his senior health experts, moved swiftly to warn the American public; the CDC recommended that pregnant women avoid travel to a dozen tropical countries. Untold numbers of vacations and business plans were cancelled. Though he was a much less well-known public figure at the time, even Dr. Anthony Fauci appeared on an ABC interview that warned women to stay away from Miami Beach.

I know nothing about Zika, nor do I have the time or energy to dive into the many research papers and peer reviewed literature generated since it first appeared. But a new commentary in the American Journal of Medicine argues that the entire scare was based on non-existent or shoddy science. It now appears that Zika is about as serious as dengue — a very nasty, but similarly dangerous virus that has long plagued tropical climates, and for which travelers should already know to exercise caution.

A key tenet of Personal Science, Nullius in verba (“take nobody’s word for it”) asks us to be critical of all claims that we can’t verify for ourselves. Following this heuristic back in 2016 could have let you enjoy sparse crowds and significant discounts on vacations to Miami and other tourist locations throughout Latin America. But it’s easy to be confident in hindsight. Only an irresponsible risk-taker would flaunt the guidance of experts — who have studied the situation far more than you ever will — just for… what? … a vacation discount?

In this case the experts were wrong. Well, not wrong — look at Dr. Fauci’s exact words: “it would not be surprising” … “take the threat seriously” but “not a likely happening”. In other words, he’s just laying out some of the scenarios, including some that turned out less dire than feared. Would you prefer that he say there’s no risk? that you should go ahead and do whatever you like, because “so far there’s no evidence”?

We have lives to live. We can’t ignore the risks, but we also can’t hide under the bed while waiting for clear answers. “Trust the experts” is not a solution — after all, how will you choose which experts to trust? Personal Science won’t give you all the answers either, but the Zika example reminds us of the importance of on-going skepticism.

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Seth Roberts

Although the term “Personal Science” has been in use since the 1990s, it was the late UC Berkeley professor Seth Roberts who introduced it to me and countless others through his popular blog, still maintained at Sethroberts.net. That site remains a treasure trove of great information about “Personal Science, Self-Experimentation, Scientific Method”, as its description notes. Even today, more than eight years after his untimely death, a search through Seth’s site will reveal prescient discussions of acne treatments, hormesis, and even inspirations from the inventor of Bitcoin. Highly recommended.

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Personal Science Week - 24 Nov 2022