All in the (network) family

Networks from very different systems fall into just a few superfamilies, say Ron Milo, Uri Alon, and colleagues (Weizmann Institute of Science, Rehovot, Israel). The superfamilies are based on the relative frequencies of certain local network motifs or recurring circuit elements that have defined information processing tasks.

Alon says he wants to “break the network down into elementary circuits and building blocks. We're very much inspired by engineering. If you want to understand the device…you break the problem up.”

He has previously found that networks have higher than expected frequencies of certain circuit elements; such elements have functions such as detecting persistence or imposing temporal order. The team now quantifies the relative occurrence of such elements in a wide variety of networks and finds that just a few...