[M]ost treatments of evolution are written in a reductionist manner in which all evolutionary phenomena are reduced to the level of the gene. An attempt is then made to explain the higher-level evolutionary process by “upward” reasoning. This approach invariably fails. Evolution deals with phenotypes of individuals, with populations, with species; it is not “a change in gene frequencies.”
— Ernst Mayr , What Evolution Is

Archive for November, 2009

The Arrow of Time in Category Theory

Thursday, November 12th, 2009

The folks at the n-Category Café have been discussing the possible relationships between time and category structure. For example, these comments from John Baez on the post “Kan Lifts”:
Why is Set so different than Setop? It’s because the morphisms are functions: relations that can be many-to-one, but not one-to-many.
Why do many-to-one but not one-to-many relations […]

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