Fourier Transforming Beer

Red Admiral Butterfly and Pink Cone Flower

Red Admiral Butterfly and Pink Cone Flower

Dan Chitwood, a member of the Danforth Plant Science Center, was the speaker this month for Science on Tap at the Schlafly Bottleworks. His talk was entitled, “What Beer Bottles and Violins Say about Evolutionary Forces that Shape Us and Our Culture”. Both his title and mine are a little disingenuous, since neither one really has much to do with beer. The software that he uses to perform his analysis does use beer bottle shapes as an illustrative example and I was drinking beer during his talk, which occurred at a brewery, but that’s about the extent of the connection with beer. Let’s just say that the smell of hops was in the air. He did talk about violin’s shapes, he plays the viola and used them as his example dataset to illustrate the concepts and theories that he applies to leaves in his work. On Tap is usually more pop science than his lecture was, but its elevated complexity seemed to hold the audience’s attention better than most of the other talks.

Stradivari violins and many of their contemporaries are some of the best and most expensive instruments in the world. The latter attribute makes them prime fodder for auction houses, which have created online catalogs, with high-definition photos of each item. Chitwood has digitized the outline of thousands of these instruments and then decomposed these irregular outlines into a sequence of ellipses that can be constructively summed to recreate the original violin outline. These sequences of ellipses are Fourier series and are a more conducive representation of the object’s shape for statistical analysis than the original pixellated outline. You knew that Fourier would be back. With these mathematical tools, Chitwood was able to describe how these instruments evolved over time and then used this example violin dataset to show how he does similar work, when he describes the shapes of leaves. Leaves are much more complex than even Stradivari violins. For one, their shapes change over time, an individual leaf’s shape changes as it grows and the shapes of leaves change, depending on where they grow on a branch or vine. All of the parts of a flower are just highly specialized leaves.

In the Q&A section, we learned that his specialty of research is the tomato. He is studying a Peruvian desert cousin to the tomato, which doesn’t taste very good and is mildly toxic, but it is highly drought resistant. He hopes to combine this last attribute into the better tasting varieties that we all know and love. With the looming specter of climate change, research into drought resistant plants is important work. One of his colleagues studies grapes. Tomatoes reproduce annually and are a good candidate for GMO techniques, but grape vines take many years to mature, making them a much more long-term project. Complicating the breeding process is the fact that all grapes are grown from grafted hybrids. Shortly after the New World was discovered, an aphid that causes root boils made it back to the Old World and started killing off all of the grapes in France. An expedient solution was soon discovered, graft Old World vines onto New World roots, a technique that is used today. However, at the time traditionalist in France forbade the use of this technique and soon all of the grapes in France died out. Chitwood threw out this story as a cautionary tale, concerning our current GMO debate.

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