Human intervention increases yeast biodiversity? Sort of.

A new article in PLOS ONE (which, being open-access, you can read for yourself) headlines with the promising title “Yeast Biodiversity in Vineyard Environments is Increased by Human Intervention.” Unfortunately, the paper probably doesn’t mean what you’re thinking it means.

The authors collected yeast from vineyards across the Azores, an archipelago off the shore of Portugal where, following the usual story, viticulture arrived with European settlers in the 15th century. The article says that more than 85% of vineyard acreage has recently been abandoned in the course of “social and economic change,” creating an array of cultivated and abandoned vineyards geographically isolated from each other and the rest of the world. This sounds like a fantastic research setting, even if you don’t take into account “doing fieldwork” meaning “walking around vineyards in the Azores.”*

As advertised, the authors took samples across these vineyards and found that the cultivated vineyards harbor higher numbers of individually distinct yeast strains than vineyards that have been abandoned for at least five years. What that means, however, is a little tricky.

The scientists picked bunches of grapes directly from vines into sterile plastic bags, crushed the grapes inside those bags, and then spread the juice onto what microbiologists call rich media** in Petri dishes, and then used DNA sequencing to identify (some of the) yeast colonies that grew on the surface of the media (jello, essentially) in the dishes. So:

  • We’re only looking at yeast on grapes, not in the soil or “in the environment” more generally. A different, maybe more interesting picture of “vineyard diversity” might have come from microbes in the soil.
  • We’re only looking at yeast willing to grow into visible colonies in two days under standard lab conditions (and the scientists also only sequenced some of those colonies). Most yeast will be happy to oblige, but not all yeast cells present in the environment will become visible colonies in dishes (and some will grow slowly. A lot of microbiology research these days side-steps that problem by sequencing all of the DNA present in a sample, but that option is, as one might expect, more expensive and more difficult. These techniques don’t mean that the older grow-in-a-dish options are completely not-useful or wholly obsolete, but they’re a good reminder that growth-in-a-dish always gives us a limited picture of a microbial world.
  • We’re not comparing cultivated vineyards with the untrammelled wilderness. We’re comparing cultivated vineyards with previously cultivated vineyards that are no longer being maintained as such. We don’t actually know anything about environments on this island where human cultivation hasn’t happened.

The authors are right: this study works against the idea that human activity always decreases ecosystem diversity. And it does say something interesting: that (at least in this setting), human maintenance increases the number of yeast species on grapes. This study continues to support the hypothesis that humans and/or their equipment are a source of vineyard yeast. It’s a good reminder, too, that “human intervention” (you could also say “humans living and working as part of the environment,” if you felt like being contrary) isn’t necessarily detrimental. Though it’s also worth remembering that increased biodiversity isn’t necessarily either “natural” or universally beneficial, either. If humans intervened to increase species diversity in the Arctic tundra, would that be a good thing? We might work on finding better ways of listening to environments telling us how they’re feeling. In the meantime, I suppose that this is a start. 


*Part of it is also a UNESCO World Heritage site.

**Rich media = lots of nutrients = easy for most yeast to grow.

The “quality” of heavy bottles and cross-modal sensory perception (Social construction of wine appreciation at ICCWS, part I)

When Dr. Charles Spence stood up to speak at the International Cool Climate Wine Symposium in Brighton a week ago, I was looking forward to the reaction of the audience as much as to his presentation. Spence is a professor of experimental psychology at Oxford, and I’ve read some of his published research. He documents examples of integrative multisensory experiences – connections amongst taste, smell, sight, sound, and touch – and experiments with ways to manipulate experiences in one sensory mode by messing about with what’s happening in our other sensory channels. The data he generates are important for marketers, who would obviously love to sell more X with an inexpensive trick like changing the music or the lighting or the colors surrounding a consumption experience.

Much of Spence’s research has involved wine quality, and most people in the wine industry are interested in marketing (not all winemakers are trying to sell more wine or sell the wine they have at higher prices, but many are); ergo, his conclusions might be useful for helping industry folk generate new marketing ideas, like harmonious wine and music pairings to sell new and different wine experiences that increase perceptions of wine quality. But more than that, crossmodal sensory perception is fun to think about, to play with the idea that how “crunchy” a chip is depends on the sound it makes and not just the physical way it feels in your mouth, or that music can “make” a wine more or less astringent. “Taste” or “smell” isn’t a fixed property of food or drink, and more environmental variables contribute to how we experience taste and smell than we usually consider. That’s good food for thinking about how attending to all of our senses in an experience can make for better living, too.

On the one hand, Spence’s observations are pretty darn mundane. Tasting with unpleasant, discordant music makes wine taste more sharp and angular. Duh? On the other, Spence’s work is unusual in this still-all-too-reductionist world, and he’s an eminent Oxford professor, and his conclusions are useful for the money-making types. So as a science communicator, I wondered, were session attendees going to be delighted? Bored? Surprised? I need to consider that a goodly proportion of ICCWS attendees were British, and as a culture the Brits aren’t exactly known for being expressive in public. But there was one moment at which I absolutely expected to hear a murmur in the crowd and didn’t.

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Fair trade and the complicated ethics of buying wine from elsewhere

My October article for Palate Press asks: “how fair is fair-trade wine?” Data exist to help answer that question, though the data are always partial, imperfect, and from a particular point of view. Other data could point to different conclusions. The data I looked at point to some of the structures of fair-trade wine and say that they’re not doing the things that ethically-minded consumers would hope or expect them to be doing.

It’s easy to think that the wine industry isn’t like growing sugarcane or coffee or rubber. I mean, most people at most wineries are pretty well off. Some are millionaires who live in mansions and sit in the front row during Paris fashion week. If you know any winemakers or vineyard managers, they’re probably comfortably middle-class people, better if you’re in a ritzy neighborhood. But the parallels are numerous once you start looking for them. Wine isn’t known for abusing child labor, but Mexican vineyard laborers working in California routinely faint from heat exhaustion, common vineyard chemicals threaten worker health (even in heavily regulated countries like France), and “employees” are often contract workers with inconsistent incomes and poor working conditions. Many operations take excellent care of their vineyard crews*, employ a year-round team, provide job security and treat their folk with dignity, but that sort of thing isn’t universal. Fair trade’s point is that enough vineyard workers in South Africa, Argentina, and Chile (where the program is active) are bad enough off to warrant an intervention in the name of social welfare. The point of the study I describe is that fair trade has a good point, but hasn’t created an intervention that does much good.

The obvious question at the end of that whole discussion is: if I’m a wine consumer who cares about what my money does in the world, if I buy free-range chicken and organic kale and go to the farmer’s market, what should I look for when I buy wine? One easy, obvious answer is to buy local. When you’ve been to the winery and know the people who work there, it’s easier to know what you’re supporting. But that solution begs the question: if all of the free-range chicken- and organic kale-eating people buy their chardonnay from their sustainability-minded regional wineries – and maybe if the people eating pasta and canned tomato sauce from the grocery store start doing the same thing – what happens to the Argentinian wine industry? Do all of those workers end up worse off because they end up out of a job?

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