Sunday, March 21, 2010

A Network Model of Biological Evolution?

Finishing Tim Ingold's piece and the book Linked by Albert-Laszlo Barabasi in the same day was more circumstance than anything, but the overlap was unavoidable.  Barabasi, a Hungarian physicist at the University of Notre Dame, has been forging a new line of research known as Applied Network Theory.  Seminal work in the field includes The Strength of Weak Ties, The Small World Problem, and more recently on power-laws: Power laws, Pareto distributions and Zipf's law

Inspired partly by computer networks, applied network theory takes the basic data structure of a network of interconnected nodes and applies it as a model to various naturally occurring phenomenon.  Some particularly good examples revealed in Barabasi's book include social networks, cell-biology and genetics, international financial markets, and everyone's favorite network, the world wide web*.  Interesting properties, of varying degrees of complexity, fall out of simple network structure like "hubs" of proportionally large inter-connectivity, "islands" of relatively segregated sub-networks, and of course weak links such as those found abundantly in social networks.

The connection to Tim Ingold's call for a organism-centric biology is not hard to see.  Network theory offers a simple and scalable model for organism-culture interaction.  A directed graph (one in which nodes' connectivity distribution is said to follow a power-law) could explain mimetic / culturgen heritability and expansion.  Networks have been used to show how companies rise to monopolies, how youtube videos go viral, and why child-naming patterns exhibit momentum.  Networks offer what could prove to be an elegant reconciliation of implicate organismal traits and their relationship to culture.

*One emergent feature of directed networks are sub-structures referred to as "tubes" which are segments in which elongated, one-directional flow occurs.  Thus, U.S. Alaskan Senator from, Ted Stevens, wasn't completely full of crap when he so elequently characterised the internet as a series of tubes.

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