Brains as “emergent systems”


One of the things that is perhaps relatively new (as a concept, 50 years is “relatively new”) in science is the idea that large groups of mutually interacting objects behave in unexpected ways.

The coolest example of this is, I think, the brain. Individual neurons are fairly well understood in terms of how the ion balance around the cell membrane changes in waves that let a bit of information travel the length of the neuron. And communication from one neuron to another via neurotransmitter chemicals is moderately well understood. And gross brain anatomy has been studied for centuries.

But putting all that together tells you very little about how a brain actually works. We know pretty thoroughly how most other organs function at all levels from macro to cellular. Kidneys, lungs, the heart, even the liver is fairly explainable. But the development of brain function is way less obvious. How is it that neurons link to each other to produce even the most basic of functions like sight processing? After all, nearly all animals have eyes that function to find food or mates, or avoid danger. The amount of processing power that, for example, is needed for a fly to detect an oncoming fly swatter and get out of the way is really pretty sophisticated. (And yeah, I know there’s also moving-air sensing that’s involved, but it doesn’t change the basic problem)

It’s been said that newborn human babies “instinctively” recognize and respond to a face. What kind of neuron interactions are needed to identify what’s a face, and then to look at it? Wow.

Evolution has had half a billion years of experimenting to get nerve communication figured out. And that communication has developed from basic motor coordination and sensing reflexes all the way to our own capacity for pondering the ability to ponder.

Well, that’s just one example of an emergent system. Culture, as interaction of many beings, is another. But that’s a topic for another day.

Makes me wonder, though. What are non-living examples of emergent systems? Would we say that the statistical mechanics of gas laws, going from classical mechanics to PV = nRT, counts?

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3 thoughts on “Brains as “emergent systems”

  1. I would include some of the classic laws of ecology – e.g. the oscillation of the snowshoe hare – lynx populations because it is a negative feedback loop with a built-in delay. Also, coevolution in general. How did cicadas work out the “clever” strategy of starving, then overwhelming, predators with the entire population hatching only every 17 years? And yes, even though the gas laws can be derived from the statistical mechanics of particles, the concept of “pressure” – a perfectly well-defined property – is “emergent” in that you don’t have to follow the trajectories of 10E23 particles to predict the results of a change in container volume.

  2. Oh, oops, you wanted nonliving examples. Um, surface tension? How about Kepler’s laws of planetary motion? Or major and minor scales? (I’m not sure the notion of “property” makes any sense without a living observer.)

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