Hierarchical organization of modularity in metabolic networks

Hierarchical organization of modularity in metabolic networks
E. Ravasz, A. L. Somera, D. A. Mongru, Z. N. Oltvai, A.-L. Barabasi

I chose this paper as an example of complexity and community structure having an effect in another field other than social science. In this case we look at the network of different metabolic interactions in E. Coli. They found that while the degree distributions of these networks have a power-law distribution, the clustering coefficient is an order of magnitude larger than what would be expected in a scale-free network. This suggests a high degree of modularity in the network.

In order to look at the groups of nodes they use standard hierarchical clustering. I would suggest more sophisticated methods of finding community structure in networks, but this works for their point. They find that the clusters correspond to functional groups. Meaning that if a chain of interactions cascades into a cluster then it would initiate a complex function into action.

Given that cell biology is very distant from my own field, I probably couldn't fully grasp what was so amazing about this paper. To me, it was useful as another reference to hierarchical structures in networks other than social networks.