Science

On horizontal transfer of code in biology, and on complexity in general

Tuesday, 27th February 2018

https://www.nature.com/articles/s41598-018-21973-y

So, I’m looking at this paper (above), and what it looks like to me is that it is another way of thinking about the idea of the horizontal in the construction and expression of the genetic code. We have already seen that bacteria and viruses (and maybe other genetic structures?) have transferred elements of their DNA into ours. The microbiome is a major part of who we are, not just as cohabitants of our bodies, but as constitutive of our genome.

We’ve already seen that, while Lamarckian genetics in its pure form might not be true, there is some sense that gene expression and environment can have an influence on genetic code. It’s not that giraffe babies have long necks because their parents stretched their necks to get the high leaves, but it is some form of feedback loop. Biological reductionism, when it comes to the constitution of the genome, is seriously questioned by all this.

Now this looks like another way of at least making the standard story about vertical inheritance more complicated. This is interesting. The idea that the complex system of biological life happens as it does not because of some idealized sense of vertical descent (and then the problem is that we just don’t know enough yet about the factors that influence that descent, but in principle we could), but because of accidents and other thing that mean that there’s no “in principle” knowledge possible.  Now, this paper is about proto-cells, in other words, long before complex organisms like humans came on the scene. Human cells, like all eukaryotes, are protected against this kind of transfer. And, obviously, vertical inheritance is still the predominant mechanism for all sorts of reasons. But even there, it is less about one gene = one expression, than about an environment of genes having a range of expressions. What Evelyn Fox Keller called the “steady state model”, as opposed to the “master molecule model” of genetics.

This is more than just a refutation of reductionism, though. If that was all it meant, we could just catalogue the various systems that might influence a complex space and still think that if we know enough about all of them, we could somehow still predict what is going to happen. But we can’t, and I think we won’t ever be able to predict at a very fine-grained level. We can speak to the success of particular kinds of species, but not what specific species will emerge in what way.

This has implications past the genome, to any complex system. The economy, large bureaucracies and states, the weather, consciousness, cultures, the creation of concepts – it all works like this. In all these cases, the idea of vertical descent of influence is only part of the story. And we know that, in some of these other complex systems. We can try to predict the weather, but there’s a reason why we can only go a few days out. If we could predict the markets, we’d be billionaires (and, those who are billionaires can’t necessarily do what the rest of us cannot do – there are many reasons for success in the market apart from prediction). We thought we could predict the 2016 election in the US, and now we treat those who did as if they have special powers. If we could predict the components of consciousness, we’d have already created it artificially. And, we are far better at identifying influences in the past for evolution than we are at predicting its outcomes.

This also means that those truisms about any of these systems are at best very rough. They work except when they don’t. Buy low, sell high. Two weather fronts meeting have a particular set of effects. Biological pressures lead to particular kinds of outcomes. Raising the interest rate has particular effects.We can say that tech stocks generally will go up, but not which specific ones will, and some of course will go down.

Does that mean that we throw up our hands and give up? No, but it means that there are limits in complex systems to the cause-and-effect logic we think is the hallmark of knowledge. And, it does suggest one reason why we have such turbulence in the political sphere. Everyone still wants that cause-and-effect logic, and will yell louder until they win the argument, that is, they have power in the government and in culture. Immigrants cause economic problems! Gays cause the breakdown of society! Guns protect people! Liberals are brainwashing our youth! Take your pick on the easy answer – every time, it is an attempt to reassert this reductionist cause-and-effect reasoning in a complex system. Even when there are regularities, it’s easy to mistake what they actually are, and easy to overplay them. It is very attractive to think that you’re the smartest one in the room.

The world doesn’t act like that. None of it does. But it is psychologically satisfying to think it does, and it builds groups to assert a series of oversimplified answers to a complex world. Those assertions are, in a sense, beside the point, though. There are always unexpected interventions in the story we think we know about how things work. A Trump comes along and wins an election. Some kids find a voice and challenge the NRA (will they be successful? Time will tell).

This is a reason for something like a phenomenological approach (which comes with a lot of humility towards these complex systems, as well as a recursive instinct that always includes the knower in the calculations of the known), and a Deleuzian approach, which thinks more in terms of material interactions than abstract rules of inference, and which is oriented toward the new rather than the predictable.

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