What makes one system more organized than another? More developed, more … civilized? How can we measure advancement? In Ecology, the Ascendent Perspective, Robert Ulanowicz has an answer. Along the way, he answers even bigger questions, like: how do we reconcile the inexorable increase in entropy with the constant growth, learning, and making going on around us?

Concept: total system throughput

Take an ecosystem, or an economy. We can measure the size (magnitude) of the system by counting its activity. In the economy, this is GDP: how much money changes hands throughout the year? The same dollar might be spent over and over, and it counts toward GDP every time. In an ecosystem, we count carbon exchanges between species and stocks (like detritus on the ground). Or we count nitrogen, or phosphorus, or calories — whichever is the limiting factor for that system. If plankton gets eaten by a minnow which is eaten by a catfish, the carbon transferred counts every time.

The system grows in magnitude when more money/carbon/nitrogen enters it, or when more exchanges happen. But does this mean it’s more developed?

Concept: average mutual information

We count the transfers, the exchanges, to measure total system throughput. But are all transfers created equal? What about the patterns of movement?

Take this imaginary ecosystem that I just made up. There are some plants and some fish. Imagine the nitrogen flows from dirt to plants to fish to fish and back to dirt. I am not an ecologist.

at the bottom, dirt. nitrogen goes into two plants. each of them go into some minnows, which go to a fish, which goes to a bigger fish. Everybody contributes nitrogen back to the soil.

There are some flows, and ecologists can measure them, with lots and lots of work.

Now imagine this same system, except all the flows are equally distributed. Every species is the same as any other, they all eat each other and poop equally.

The same components, but now each one is connected to each one by an arrow of the same thickness.

The first picture looks more organized, right? In the second picture, it is maximally random where the carbon goes. The first ecosystem is more ordered. Nitrogen is moving through these pathways for reasons, not willy-nilly everywhere. Ulanowicz came up with a formula for quantifying the difference, and he calls it average mutual information (AMI). Because, the part where the plants don’t eat the fish is informational, it says something about the system, about which pathway is more efficient.

Concept: ascendency

Both the total system throughput and the un-randomness in the system (AMI) contribute to its significance, its organization. So Ulanowicz multiplies these (or something similar, the math is in the book at a high level and in his other works at a detailed level) and that’s Ascendancy. How much does the system do, and how interestingly does it do it?

Concept: efficiency and overhead

For a given system throughput, a maximally ascendent system would have like one path in a circle. Only the most efficient path would be used. There wouldn’t even be two plants.

Thinking about it this way, you can divide the system throughput into the part that contributes to ascendency, and the rest. The rest is overhead. It’s all those extra pathways, which, what is even the point?

The point is flexibility. Resilience. A perfectly efficient system is maximally fragile. One disruption, one disease kills off the single plant, and the whole thing done, everybody’s dead. No more flows, no more fishes.

Overhead, unpredictability, extra pathways, these are what keeps the ecosystem alive and flourishing under changing conditions. They let it change without dying out.

Efficiency vs Resilience

This illustrates that there is a conflict between efficiency and resilience. Organization is important — it often leads to system growth — and also limiting.

The ascendency of the economy is higher if, for the same GDP, money flows toward fewer corporations. But is that the most resilient?

Our teams are more efficient if there is exactly one path of information flow. But human communication is always partial, and broad social pressures direct us more constructively than a single financial incentive.

The concept of ascendency is useful in many ways, as detailed in the book. It incorporates and raises broader philosophical points, which come up in my other post about this book. “The world as we perceive it is the outcome … of a balanced conflict — the opposition of propensities that build order arrayed against the inevitable tendency for structures to fall apart.”