The Epigenetics Revolution by Nessa Carey
June 26, 2000, may well go down as one of the most monumental days in human history. It was a day of huge scientific achievement, as the international team behind the Human Genome Project announced they’d successfully mapped the human genome, for the very first time. We finally had the code to unlock the secrets of human life.
But, of course, things didn’t end there. Science never stands still, and in these blinks, we follow the story of what’s been happening since June 2000. We’ll go beyond the human genome, zooming right in to focus on the new frontier of genomic research: the study of epigenetics.
We’ll learn how the genetic code inside your cells gets turned on and off, what causes the changes, and how they happen despite your DNA remaining unchanged.
Epigenetics isn’t important just because it’s at the forefront of biological research. It’s also significant because of the outsize role it plays in our lives more generally: from obesity to trauma and cardiovascular health to metabolism, epigenetics underlies some of the most important processes in our bodies.
Along the way, we’ll see what a discredited evolutionary theory actually got right, discover what famine teaches us about human development, and examine the biological basis of psychological harm.
If you want to move past the simple 2D picture of human health that standard genetics provides, then you’re in for a treat.
In these blinks, you’ll learn
• why your DNA only tells half the story;
• how your granddad’s diet might be affecting your health today; and
• what a few overstressed mice can teach us about childhood neglect.
Epigenetics explains what standard genetics can’t.
Mapping the human genome was a gargantuan task. Identifying and analyzing all of the genes that make up a human being is no small feat, even for a team of dedicated experts – so it's no surprise that the project’s completion led to wild fanfare and public enthusiasm.
Bill Clinton, who was president when the genome was first fully sequenced, went on record to say, “Today we are learning the language in which God created life.” The UK Science Minister, Lord Sainsbury, declared, “We now have the possibility of achieving all we ever hoped for from medicine.” Big statements, from powerful men – but in hindsight, were they all that accurate? Well, perhaps not entirely.
Part of the problem was that we overestimated the importance of DNA. We thought of it as a huge set of strict biological instructions, like a mold for making identical parts in a factory. But as it turns out, the reality is really quite different.
You see, we might be better off thinking of human DNA as a script rather than a mold. Let’s consider an actual theater script for a minute. Take Shakespeare’s Romeo and Juliet, for example – although every production takes Shakespeare’s words and stage directions as their starting point, each performance ends up different, because the script can be interpreted in so many different ways.
During rehearsals, the director and actors will scribble their own notes and instructions in the margins of their starting scripts – and in doing so, they turn the initial work into something new and idiosyncratic.
So, what does that have to do with biology? Well, if we think of living things as theatrical productions, then DNA is the first script we’re given to work with – our original masterpiece. Add in those all-important jottings in the margins that make each script unique? Well, that’s epigenetics.
Epigenetics controls the expression of our genes – directing the extent to which any one gene carries out its function. Epigenetic modifications are like the actor’s little notes saying, “Speak these words quietly,” or “Shout this bit,” or even “Skip this line entirely.”
In other words, they’re the unique instructions that tell the individual cells that make up your body how to behave in different circumstances. Epigenetic information is what stops a skin cell from turning into a neuron, or a liver cell from turning into skeletal muscle.
Just as Shakespeare’s play can give rise to both traditional performances in Renaissance style, and modern interpretations like Baz Luhrmann’s 1996 film, so too can a single “script” of DNA give rise to very different characteristics.
To understand this a bit more, let’s forget about Romeo and Juliet for a minute, and focus on a less appealing topic: mice – inbred lab mice, to be exact.
Now, these mice aren’t inbred through any fault of their own. Their human handlers have bred them selectively with their siblings generation after generation, to the point that they have become genetically identical. And yet, despite each mouse seeming identical to its siblings at birth, as the mice babies grow, they begin to show their differences – in things like their body weight and temperament, for example. And this is despite being kept in exactly the same environment.

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