Macroepigenetics for beginners

Clearing out the stable manure this morning my heart was lifted by the sight of a large flock of ravens interacting with a large flock of carrion crows in quite a complex way. It seemed to be one of those “close to nature” moments that is a bit more subtle than sunsets¬† and so on. Consulting my limited library on British birds I couldn’t find anything about such conjoined flocks (strictly it was a congress of ravens with a murder of crows), until it occurred to me that there was probably just a dead deer or badger in the wood nearby. Nevertheless it got me to thinking about the origin – and the evolution – of complex behaviour.

An old 2001 article about Paul Ehrlich¬† (the living American, not the dead German) showed his dismissal of the whole field of evolutionary psychology on the very reasonable grounds that the human genome doesn’t contain anything like enough genes to determine the state of the billions of cells in the nervous system, even if they were all dedicated to the task.

“But genes must also contribute to the assembly of all our other complex organs. Even if we had a million genes that could be dedicated to our brains, they couldn’t begin to determine how those nerve cells interact,” he stated. “Our genes have more than enough to do just making us extraordinarily smart, giving us the physical talents required for speech and tool making, and influencing a few key behavioral features such as our interest in sex and our penchant for keeping track of who’s related to whom.”

He also muses on how little we know of the generation of ideas and how knowledge about their spread is greatest in unlikely fields such as marketing, as well as making some interestingly non-self-aware references about changing society for the better:

According to Ehrlich, “We must strive to evolve a new ethic that would have almost everyone put preserving humanity’s vital store of natural capital — the microorganisms, plants and other animals of Earth — near the top of their ethical priorities. Scientists need to direct that evolution by ‘marketing’ such a set of ethics, doing the necessary market research, selecting appropriate goals, creating appropriate images and emotional associations, and carefully monitoring the performance of the ‘product.'”

Two observations, as an aside, here: firstly, note his subtle shift from professing ignorance about the origin of human culture, to the assumption that scientists know what is best for that culture and should impose it by successful marketing. And secondly, the call to “strive to evolve a new ethic”, and to “direct the evolution” of society, which rather cuts across the allegedly fundamental basis of evolution as an intrinsically unsupervised, non-teleological and undirected process. Either Ehrlich’s a closet ID supporter, or the word “evolution” is being misapplied – Gregory will no doubt wish to comment!

But my main point here is simply that Ehrlich is clearly right in saying that complex human behaviour cannot possibly be the result of genetics, and so it cannot possibly be the result of Darwinian evolution. Certainly there is a shortage of any plausible evolutionary mechanisms for it, despite the banale Darwinian rationales for the selective advantage of certain behaviours. In the case of humans, many other mechanisms must be considered, from the use of reason to the spread of ideas and even to the revelation of God.

But if the case against genetics as the explanation of behaviour applies to humans, then it also applies to animals like my corvids. If I do not have not enough genes to determine my taste in music or natural phenomena, I doubt ravens have enough to program their wonderful aerobatic antics. Nor, even, does it seem that likely that genetics alone can explain how the large blue butterfly developed its astonishing lifestyle.

The most likely known factor (going back to my social psychology days) is, of course, learned behaviour – the social environment. Whether, and how, such influences are the whole explanation, the point is that a large part of the natural world around us is not the result of genes, and so is not the result of evolution.

There’s a parallel here with the cell, and the role of epigenetics. Once we realise that every organism inherits not only DNA, but a cell, from its parents there is a host of possible explanations for life’s variety apart from the genes. In the same way, no organism comes into the world apart from its environment. It learns, mimics, chemically imbibes or by whatever other means becomes far more than the product of its genetic inheritance. So one could view socially conditioned behaviour as the macroepigenome if the term hadn’t already been hi-jacked by people working way down the scale of magnitude. Hypermacroepigenetics, anyone?

This in turn, surely, must influence the direction of evolution. Take Darwin’s sexual selection, for example. If the peackock’s tail or the dinosaur’s feathers followed the direction decreed by female preferences, then we owe the spectacle of the former to non-genetic complex behaviours more than to RM & NS. In the case of the latter, we could attribute the origin of bird flight ultimately to social fashion in the theropod clubbing world. If ravens have developed their aerobatics out of pure fun – and once you exclude genetics that’s as good a reason as any – then flying ability is selectable simply because the poor flyers crash from over-confidence. But if the best of the next generation raise the stakes because they can do more cool tricks for pleasure, there’s actually a very Lamarckian thing going on. “Fun” becomes the selective pressure, and the “behaviourome” (unless someone’s coined a better term) the distinctly non-random and teleological agent that drives it. You don’t often hear the phenomenon of flight explained by the combination of femine whim and childish play.

Or did I miss something?

Jon Garvey

About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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One Response to Macroepigenetics for beginners

  1. James Penman penman says:

    I’ve long thought that the complexity of social organization & behaviour in parts of the animal kingdom is one of the most difficult phenomena to accommodate within the now traditional “random mutation plus natural selection” model of evolution. Fortunately thinkers like Shapiro & Conway Morris seem to be opening up vistas onto other mechanisms that can account for these stunning complexities. Looks like the great Garvey is among their number too….

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