Cold hard complexity: learning to talk in nature’s language

by Paul Curzon, Queen Mary University of London

A gentoo penguin slumps belly-first on a nest at Damoy, on the Antarctic Peninsula. Nearby some lichen grows across a rock, and schools of krill float through the Southern Ocean. Every one of these organisms is a part of life in the Antarctic, and scientitsts study each of them. But what happens to one species affects all the others too. To help make sure that they all survive, scientists have to understand how penguins, plants, krill and everything else in the Antarctic interact with one another. They need to figure out the rules of the ecosystem.

Working together

When you’re trying to understand a system that includes everything from plants to penguins, things get a bit complicated. Fortunately, ecology has a new tool to help, called complexity theory. Anje-Margriet Neutel is a Biosphere Complexity Analyst for the British Antarctic Survey. It’s her job to take a big puzzle like the Antarctic ecosystem, and work out where each plant and animal fits in. She explains that ‘complexity is sort of a new brand of science’. Lots of science is about isolating something – say, a particular chemical – from its surroundings so you can learn about it, but when you isolate all the parts of a system you miss how they work together. What complexity tries to do is build a model that can show all the important interactions in an ecosystem at the same time.

Energy hunt

So for a system as big as a continent full of species, where do you start? Anje’s got a sensible answer: you start with what you can measure. Energy’s a good candidate. After all, every organism needs energy to stay alive, and staying alive is pretty much the first thing any plant or animal needs to do. So if you can track energy and watch it move through the ecosystem, you’ll learn a lot about how things work. You’ll find out what comes into the system, what goes out and what gets recycled.

Playing with models

Once you’ve got an idea of how everything fits together you’ve got what scientists call a model. The really clever thing you can do with models is start to mess around with them. As an example Anje says, ‘What would happen if you took one group of organisms and put in twice as much of them?’ If you had a system with, say, twice as many penguins, the krill would have to be worried because more penguins are going to want to eat them. If they all run out what happens to the penguins? Or the seals that like eating krill too? It gets complicated pretty quickly, and those complicated reactions are just what scientists want to predict.

The language of nature

Figuring out how an ecosystem works is all about rules and structure. Ecosystems are huge complicated things, but they’re not random – whether they work or not depends on having the right organisms doing jobs in the right places, and on having the right connections between all the different parts. It’s like a computer program that way. Weirdly, it’s also a bit like language. In fact, Anje’s background is in studying linguistics, not ecology. Think of an ecosystem like a sentence – there are thousands of words in the English language but in order to make a sentence you have to put them together in the right way. If you don’t have the right grammar your sentence just won’t make sense, and if an ecosystem doesn’t have the right structure it’ll collapse. Anje says that’s what she wants to discover in the ecosystems she studies. ‘I’m interested in the grammar of it, in the grammar of nature.’

Surviving Antarctica

Since models can help you predict how an ecosystem reacts to strange conditions, Anje’s work could help Antarctica survive climate change. ‘The first thing is to understand how the models work, how the models behave, and then translate that back to the biology that it’s based on,’ she explains. ‘Then say OK, this means we expect there may be vulnerable areas or vulnerable climate regions where you can expect something to happen if you take the model seriously.’ If scientists like Anje can figure out how Antarctica’s ecosystems are set up to work, they’ll get clues about which areas of the continent are most at risk and what they can do to protect them.

Surviving on a continent where the temperature hardly ever gets above freezing is tough, and climate change is probably going to make it even tougher. If we can figure out how Antarctic ecosystems work, though, we’ll know what the essential elements for survival are, and we’ll have clues about how to make things better. Extracting the secret grammar of survival isn’t going to be a simple job, but that’s no surprise to the people working on it. After all, they’re not called complexity scientists for nothing.


This article was originally published on CS4FN and can also be found on pages 10-11 of CS4FN Issue 9, Programmed to Save the World, which you can download as a PDF. All of our free material can be downloaded here: https://cs4fndownloads.wordpress.com/


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This blog is funded through EPSRC grant EP/W033615/1.

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