"Fusion" is an important concept in nearly all artistic fields -- music, cooking, painting, what have you. Each endeavor tends to feature multiple strongly-identified styles -- Mexican food, Japanese food, Ethiopian food...; Jazz, Classical, Rock...; Impressionism, Abstract Expressionism, Pop... -- and it is fun to mix and match to obtain exciting new combinations. Here in Chicago, you can visit SushiSamba for Latin/Japanese cuisine, then head over to the Empty Bottle to listen to some jazz/rock hybrid. Despite the excitement, however, genres do not just blend together to form one homogeneous goop. While styles evolve, they are typically held together by distinct aspects setting them apart from other approaches. (Latin/Japanese fusion will never grow in popularity to displace the authentic cuisines of either region.) This can be informally understood through the concept of a fitness landscape, a function of the underlying variables that describes how successful a certain approach ultimately is. A typical fitness landscape has peaks and valleys, indicating that particular combinations work well together, much better than a random mish-mash. Imagine setting aside our delicate sensibilities for a moment to contemplate a giant "food machine" (or "music machine" or whatever) that can create any dish we want, simply by adjusting the position of a large set of dials. (A thought experiment, okay?) There's a dial for the amount of jalapeno peppers, another dial for how long the food should be cooked, and so forth. There is a region of dial settings that corresponds roughly to "Japanese food" and another that corresponds to "Latin food." If we simply adjust the dial setting to be a linear combination of the Japanese and Latin settings, the likely outcome is -- some sort of horrifying mush. We would find ourselves in a valley of the fitness landscape where nobody would want to live. In other words, different approaches to cuisine (or other artistic endeavors) tend to cohere into sensible and distinct groupings, and random mixtures between them are unlikely to be an improvement; successful fusion is a delicate art. Interestingly, however, there is a well-known counterexample to the peaks-and-valleys structure of aesthetic fitness landscapes: human faces. It's been known for a while now that if you take a selection of randomly-chosen people, and construct a picture by averaging their features together, the result is typically a more attractive person. The phenomenon is extremely easy to notice in examples. Alex Tabarrok at Marginal Revolution writes about an experiment that tested this conclusion. He extracted this figure from Judith Rich Harris's book No Two Alike. From top to bottom, it shows some actual faces, then the average of two faces, four faces, and so on up to 32 faces.
For an even more striking demonstration, see The Face of Tomorrow, a photography project that takes portraits of random people in certain cities around the world and blends them together (city by city), with the idea that these composite portraits will resemble future citizens in an increasingly interconnected world. (Alas, real heredity doesn't work that way -- stupid discretized genetic code.) Go to The Faces and click on a city to see the composites decomposed into the individual people. The future, I have to say, looks pretty hot.
