… by Michael Graham Richard, Ottawa, Canada on 03. 3.10

Lemon leaf with interconnected loops. Photo: RU

A team of biophysicists at Rockefeller University recently published a paper in Physical Review Letters about a new way to design distribution networks based on the veins that carry water and nutrients in most tree leaves. This is a great example of biomimicry! Evolution by natural selection maybe be blind, but it has had billions of years of trial-and-error to figure out efficient and robust ways to do things. The interconnecting vein loops in leaves are a good example of that, and we can learn from them.

Ginko leaf, without interconnected loops. Photo: RU

“Operations researchers have long believed that the best distribution networks for many scenarios look like trees, with a succession of branches stemming from a central stalk and then branches from those branches and so on, to the desired destinations. But this kind of network is vulnerable: If it is severed at any place, the network is cut in two and cargo will fail to reach any point “downstream” of the break.”

A good example of that can be seen on the two pictures in this post. The big dots are damage in the network. In the pic on top, you can see that the flow isn’t stopped, and can go everywhere in the network. In the second pic, the flow is stopped everywhere downstream of the damage point.

“Operations researchers have appreciated that these redundancies are an effective hedge against damage. What’s most surprising in the new research, according to Marcelo O. Magnasco, head of the Laboratory of Mathematical Physics at Rockefeller University, is that the complex network also does a better job of handling fluctuating loads according to shifts in demand from different parts of the system — a common real-world need within dynamic distribution networks.”

This kind of network full of loops can also be found in the blood vessels of the retina, the architecture of some corals, and the structural veins of insect wings.

It remains to be seen if the benefits of more robust and easy to balance networks will outweigh the negatives (it would probably be more expensive), but I think resilience and robustness are worth a lot since our society is so dependent on these networks.

For something a bit similar, check out how slime mold can help design public transit networks.

Via Physical Review Letters, Rockefeller University