As has by now been widely publicized in wine circles and elsewhere, Dr. David Mills and graduate student Nicholas Bokulich of UC Davis have just published a journal article (in the Early Edition of the Proceedings of the National Academy of Sciences here) demonstrating that populations of bacteria and yeast associated with wine grapes vary geographically in organized and predictable ways. Bokulich collected samples across California, isolated bacteria and yeast from those samples, sequenced bits of their DNA, and then looked for patterns.
This is a beautiful, extremely strong study with useful implications. Unfortunately but unsurprisingly, the news headlines are getting much of it wrong. The New York Times article on the subject* sets up the long-standing American skepticism about terroir, then proclaims that “American researchers may have penetrated the veil that hides the landscape of terroir from clear view, at least in part. They have seized on a plausible aspect of terroir that can be scientifically measured – the fungi and bacteria that grow on the surface of the wine grape.” This is the kind of unscientific media hogwash that contributes to people on the street having balderdash-worthy ideas about how science works. I can’t blame the article’s author for being one more journalist who doesn’t understand science (or who knows better but still needs the sexy story). I can blame the NY Times for not having the sense or taking the effort to get someone with enough research knowledge to cover the story well (Inside Scoop SF did, though they do have Jon Bonné). You’re the NY Times; you folks can do this.
Problem #1: Bokulich and Mills’ findings don’t actually say anything about terroir as we typically talk about it: in terms of sensory impact. The paper describes regional variations. The paper doesn’t connect those variations with any element of wine quality, perceptible or otherwise.
Problem #2: This is not the first time researchers have attempted to quantify some element of terroir. Not even close. Geologists and pedologists (soil scientists) have done a lot of good work looking at soil structure, depth, aspect, and so forth. Other microbiologists have looked at differences in bacteria and yeast across space. Bokulich’s study is exceptionally strong, but it’s not as earth-shatteringly unique as the media are making it out to be.
Problem #3: A technical point, but Bokulich and Mills didn’t actually look at microbes on the surface of grapes. They collected grape musts, which for them meant “destemmed, crushed grapes, representing a mixed, aggregate sample of all grapes from an individual vineyard block” collected after ordinary stemming and crushing operations at the winery. The strength of looking at musts is in having a sample that reflects averaging across a vineyard block and does away with potentially idiosyncratic variations between individual grapes. The main weakness is that we’re a lot less sure of where the microbes came from. What if some of the microbes came from the winery equipment or from handling operations instead of being present on the grapes in the vineyard? Significant regional patterns correlated with environmental factors – precipitation and temperature, for example – but we still can’t actually pinpoint where those microbes are originating.
The NY Times article does a pretty good job of summarizing the original PNAS paper. Kudos to it’s author for talking a bit about the methods behind the findings, for observing near the end of the piece that “the Davis scientists still need to prove that these microbes affect the quality of the wine,” and for calling up Dr. Thomas Henick-Kling at Washington State University for a second opinion. The problem is in the headline and the first few paragraphs which are, of course, what get picked up and misconstrued by everyone else.
This is a fine example of a frequent pattern in news science coverage. Researchers publish a paper on a sexy topic like wine or cancer, and – being like other humans – their conclusions about the implications of their findings might take a few steps over the bounds of reasonability. The university and/or the academic journal puts out some kind of press release, highlighting the sexy bits and the in-our-dreams implications. Journalists pick up on the sexy bits and elaborate even sexier hooks and headlines around them. The hooks and headlines get picked up by less reputable news replicators and on Facebook and Twitter. And by now we’re wandering around smack-dab in the middle of unreasonableness territory.
A chicken-and-egg problem: do we get headlines like this because national science literacy is bad, or does poor science literacy stem (in part) from the uncritical quality of our media? Either way, there’s improving to be done here.
- Wine-Searcher’s coverage has to get an honorable mention, not only for its especially unreasonable tag line – “New research suggests that bacteria and fungi could be as important in the expression of regionality as soil and climate” – but for referring to what we all know and love as Botrytis cinerea or Noble rot by the show-worthy name of its anamorph (another form of the same fungi), Botryotinia fuckeliana.