Epigenetics: Are Genes The New Brains?

By Neuroskeptic | September 26, 2013 7:13 am

Over at the Pacific Standard, David Dobbs writes on: The Social Life of Genes

It’s an excellent piece about epigenetics and gene expression – the process by which particular parts of our DNA are ‘switched on’, or off, within cells:

Genes can vary their level of activity, as if controlled by dimmer switches. Most cells in your body contain every one of your 22,000 or so genes. But in any given cell at any given time, only a tiny percentage of those genes is active.

This is well-established biology; what’s new is the idea that:

The environment could spin the dials on “big sectors of genes, right across the genome” – and that an individual’s social environment might exert a particularly powerful effect. Who you hung out with and how they behaved, in short, could dramatically affect which of your genes spoke up and which stayed quiet – and thus change who you were.

For instance, comparing socially isolated people to others, researchers Cacioppo and Cole found that:

Of roughly 22000 genes in the human genome, the lonely and not-lonely groups showed sharply different gene-expression responses (in leukocytes) in 209 genes. That meant that about one percent of the genome – a considerable portion – was responding differently depending on whether a person felt alone or connected…

Whole sectors of genes looked markedly different in the lonely and the socially secure. And many of these genes played roles in inflammatory immune responses…

Good stuff, and there’s plenty more detail (including some remarkable studies of bees) in Dobbs’ piece.

But while reading the article I felt an odd sense of deja vu. Why? I don’t know much about genes. I’m a brains guy. But then I realized, that was it – I’d heard this kind of thing before about brains.

Here’s a bit from near the end of the article, where Dobbs is in conversation with epigeneticist Steven W. Cole. I’ve just made a little adjustment:

We were in fact skirting the rabbit hole that is the free-will debate. Yet he wanted to make it clear he does not see us as slaves to either environment or brains.

“You can’t change your brain. But if we’re even half right about all this, you can change the way your brain behaves – which is almost the same thing. By adjusting your environment you can adjust your brain activity. That’s what we’re doing as we move through life. We’re constantly trying to hunt down that sweet spot between too much challenge and too little.

“That’s a really important part of this: To an extent that immunologists and psychologists rarely appreciate, we are architects of our own experience…”

Cole was talking about genes, but couldn’t he almost have been discussing brains? I’m thinking here of the recent discussions about neuroplasticity, the idea that the environment can alter brain structure and function. The story is the same: “We used to think that biology determined our lives, but now we know that life can influence biology.”

There’s a lot of truth in that, in both cases.

However, if genes are the new brains, then epigeneticists will need to be careful not to fall into the same traps that neuroscientists are only just learning to avoid.

One thing we’ve learned that it’s easier to measure brain activity than to interpret it. Brain activity-behaviour correlations are ten a penny, but the mere fact that the brain is activated by something, or activated differently in two groups of people, tells us nothing. Working out what causes what, what’s important and what’s trivial, is the goal, and it’s not an easy one to achieve.

There are 22,000 genes; there are some 20,000 voxels in the average fMRI scan of the brain, so even the statistics of analyzing their activations are quite similar.

Finally, it seems I’m not the first to spot the parallels here, because three years ago Greg Miller wrote a piece called The Seductive Allure of Behavioral Epigenetics. This was surely an allusion to The Seductive Allure of Neuroscience Explanations, the famous 2008 paper about fMRI.

  • http://jayarava.blogspot.com Jayarava

    Goodbye selfish genes.

    Hello social genes.

    • bobgeezer

      Hello selfish genes.
      Goodbye social genes.

      • cgosling

        Social genes are selfish genes, are they not?

        • bobgeezer

          I don’t know. As far as I know, there’s no such thing as social genes. Selfish genes have been known for about 30 years.

  • http://daviddobbs.net/ David Dobbs

    You’re spot on: Both scientists and those who write of their work need to tend to both the potential and the pitfalls of exploring how gene activity shapes behavior. I think it vital too to distinguish between what’s reasonably buttressed with evidence and what is speculation about what we might find digging further: thus my care to note, in my account of my conversation with Cole, the point at which we had moved from one to the other.

    The other thing that scientists, writers, and readers need bear in mind: The other parallel between neuroscience and genetics is the extreme youth of the two fields: How incredibly early we are in understanding the brain or the genome. The potential of genetics to help explain things is tremendous; but as many a geneticist knows from the disappointments of the human genome project, it’ll likely be rare when we find straight-line mechanical explanations for things so complicated as behavior. What to make of a correlation between activity in 200+ genes and a state of mind? That’s a slippery, difficult question; watching someone pursue it has its own value. If we’re to accept that science is not a set of answers but a way of looking for them, we have to be willing to observe that search without demanding final answers.

  • Pingback: Post Of The Week – Thursday 26th September | DHSG Psychology Research Digest()

  • http://petrossa.me/ petrossa

    good piece. I love “Brain activity-behaviour correlations are ten a penny, but the mere fact that the brain is activated by something, or activated differently in two groups of people, tells us nothing” wish more people could accept that simple fact. The number of silly publications would drop enormously, as my would my blood-pressure

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  • Wouter

    I do have some problems with the interpretation of genes that react immediately to the environment; real-time reaction, so to speak. Although I can see the (evolutionary) benefit of genes adapting to the environment, I can’t see the benefit of genes adapting to whom you spoke with. Furthermore, as Neuroskeptic points out, such interpretation shows great similarities to neural behaviour. For me, it seems unlikely that mammals would have two amazingly complex systems that would actually perform the same task. Seems awfully costly for such redundance. So, my best guess would be that either the brain or the genes do not adapt to the environment in real-time.

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Interesting point. Given that we have a flexible brain, why have flexible gene expression as well? Well, I suppose – because the brain can’t control what happens inside cells… except indirectly by regulating gene expression. The brain generates behaviour directly but it can only affect e.g. the level of immune cells, indirectly.

  • scienceisherenow

    Interesting piece of data: domestication, which probably has a high impact on brains, seems to associate (not known if cause or effect) with epigenetic alterations. The data comes from silkworms and was published online on the 23rd September in BMC Genomics (reviewed in
    scienceisherenow.scienceblog.com)

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Neuroskeptic

No brain. No gain.

About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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