The Worm & Fly & Science Problem

by Nina

Just a part of NY Times Diagram

As some of you may know by now, my husband, Dr. Brad Gibson, is a medical researcher who works at a research institute where the focus is on aging and age-related diseases. So I hear about a lot of studies that claim to have discovered this or that supplement or food that will slow aging or lengthen our life spans. We are often quite skeptical, especially when we learn about how the studies were done. Because it is expensive and time-consuming to test human beings (and sometimes unethical), these studies are often done on worms and flies. And concluding that the effects are going to be the same on human beings is rather a stretch. 

I was motivated to write about this today after seeing a wonderful graphic in the Sunday New York Times in the article A Handy Guide to Longer Living Through Science! (I'm pretty sure the title is ironic.) I actually started to laugh when I read that the study that proved green tea extends life was done on flies (and the one that proved that it won’t was done on mice). A lot of the other studies on supplements were done on worms.

There’s a reason for this. Worms and flies have very short life spans and also visible signs of aging. Yes, older worms get quite wrinkly, for example. So it’s easy to change something about their diet and then see an obvious result, either in a longer-than expected life span or some other physical change. But does that mean the same thing would happen in a human? 

Brad says:

"I suppose its no accident that the artist who created the graphic used a "mouse maze" of conflicting, supporting or just plain absurd experimental results that have been published in the last three years alone to illustrate the disarray of lifespan research. While we all would have our favorites, for example, "worms live longer in outer space" or "men decrease women's life spans" (sorry, dear), these studies point to several underlying assumptions (or misassumptions) about how scientists go about studying longevity or health span. For one, we use a number of model organisms, with worms, flies and mice being the favorites. This is obvious to anyone thinking about conducting such a study, as these animals live anywhere from a couple of weeks to 2-3 years at most. Two, as we compare results of similar regimens across these organisms, we get a lot of contradictory results—maybe not a huge surprise. However, the more troubling truth is that even when we use the same model organism, the results can be very different (Rapamycin slows aging in mice, Rapamycin doesn't slow mice aging). The reasons behind this are complex, but could be due to differences in mouse strain, or the lab they are raised in (different gut microbiome!). My read on this? Here goes: avoid gimmicky lifespan-increasing supplements and drugs and, of course, get plenty of exercise like yoga, as all studies seem to indicate a big beneficial effect in daily exercise." 

So have fun looking at this graphic summary of recent studies on aging. I myself was thrilled to see that the study that showed coffee extends life was done on humans! But wait—there was another study done on humans that shows coffee decreases life spans. Sigh. 

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