Red King – listening to coevolution

Scientific models are used by researchers in order to understand interactions that are going on around us all the time. They are like microscopes – but rather than observing objects and structures, they focus on specific processes. Models are built from the ground up from mathematical rules that we infer from studying ecosystems, and they allow us to run and re-run experiments to gain understanding, in a way which is not possible using other methods.

I’ve managed to reproduce many of the patterns of co-evolution between the hosts and parasites in the red king model by tweaking the parameters, but the points at which certain patterns emerge is very difficult to pin down. I thought a good way to start building an understanding of this would be to pick random parameter settings (within viable limits) and ‘sweep’ paths between them – looking for any sudden points of change, for example:

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This is a row of simulations which are each run for 600 timesteps, with time running downwards. The parasite is red and the host is blue, and both organism types are overlayed so you can see them reacting to each other through time. Each run has a slightly different parameter setting, gradually changing between two settings as endpoints. Halfway through there is a sudden state change – from being unstable it suddenly locks into a stable situation on the right hand side.

I’ve actually mainly been exploring this through sound so far – I’ve built a setup where the trait values are fed into additive synthesis (adding sine waves together). It seems appropriate to keep the audio technique as direct as possible at this stage so any underlying signals are not lost. Here is another parameter sweep image (100 simulations) and the sonified version, which comprises 2500 simulations, overlapped to increase sound density.

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You can hear quite a few shifts and discontinuities between different branching patterns that emerge at different points – writing this I realise an animated version might be a good idea to try too.

Stereo is done by slightly changing one parameter (the host tradeoff curve) across the left and right channels – so it gives the changes a sense of direction, and you are actually hearing 5000 simulations being run in total, in both ears. All the code so far (very experimental at present) is here. The next thing to do is to take a step back and think about the best way to invite people in to experience this strange world.

Here are some more tests:

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