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sexta-feira, março 14, 2008

Food for Thought

Ainda sobre o paper noticiado na Nature News. Para quem ficou com preguiça de ir até o ArXiv Blog, reproduzo aqui o post com o comentário respondendo à crítica (ou dúvida) feita, que por sinal também nos foi feita por Mark Buchanan, autor de Ubiquity, um livro que eu recomendo para todos os meus orientados.

Food for thought

March 4th, 2008 by KFC

Food for thought

Evolution seems to crop up all over the place. In life, business, ideas. And now in recipes through the ages.

Yup, that’s recipes. For food. Osame Kinouchi from the Universidade de São Paulo in Brazil and buddies, have studied the way in which ingredients used in recipes vary around the world and through the ages. And they’ve found, they say, evidence of evolution.

The team studied the relationship betwen recipes and ingredients in four cookbooks: three editions of the Brazilian Dona Benta (1946, 1969 and 2004), the French Larousse Gastronomique, the British New Penguin Cookery Book, and the medieval Pleyn Delit.

They took the recipes from each book, counted the number of times each ingredient appeared in these recipes and ranked them according to frequency.

What’s remarkable is that the frequency-rank distribution they found is more or less the same for each cookbook. Kinouchi and co say this can be explained if recipes evolve in much the way that living organisms do–in a landscape in which some ingredients can be thought of as fitter than others, in which random mutations take place, and some ingredients die out while others prosper.

Very clever…unless they’ve missed something.

Perhaps it’s not ingredients that produce this distribution but words themselves. I’d be interested to see whether the results they get would be significantly diffierent were they to examine the frequency of adjectives or colours or numbers in these books rather than ingredients. If not, then recipes have nothing to do with the results they are presenting.

Of course, it’s possible that recipes have evolved in the way the group suggests. But the evidence they present here doesn’t look convicing to me.

Ref: arxiv.org/abs/0802.4393: The Nonequilibrium Nature of Culinary Evolution

One Response to “Food for thought”
  1. By Osame Kinouchi on Mar 14, 2008 Reply

    Hi, it is interesting that Mark Buchanan asked us with the same question this week. Here is our reply to him (and thanks for the comment about our work, anyway…):

    Dear Mark,

    We thank you for your interest in our paper and are available to give you any needed information for you to write your article.

    Answering your question, we are aware of the “ubiquity” of power laws (we have enjoyed very much reading your book). However, we think that our finding is not directly related with Zipf’s law as you seem to be suggesting.

    This is because there is a clear “physical” interpretation of f(r): it is the percentage of recipes where ingredient with rank r occurs, for example, thyme has rank 13 in the New Penguin Cookery Book not because it is a common word in English or in cookery books but because it is well used in the recipes of this particular book.

    We also would like to emphasize that we did not count how many times an ingredient name appears in a book but how many recipes use that ingredient.

    Of course, perhaps, there is a lexical Zipf’s law for ingredient names — as well as for adjectives, nouns, etc –, probably with a different exponent (the classic lexical exponent is about 1 and our exponent is about 1.4).

    We think that our law is not lexical but reflects the relative popularity of ingredients in each culture. As another example, the frequency of given names in the population probably follows a power law, which is not a Zipfian lexical law but reflects the copy-mutation mechanisms underlying name transmission within society.

    Best regards,
    Osame and Antonio





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