Siddhartha Mukherjee's recent article on epigenetics has drawn heavy criticism—rightly?by Philip Ball / June 7, 2016 / Leave a comment
When I first saw the avalanche of anger and complaint from scientists directed at an article in the New Yorker written by Siddhartha Mukherjee, I couldn’t help wondering: what could it possibly be about this young, Pulitzer-prize winning Ivy League professor and one-time Rhodes scholar that has set people’s backs up so? But the truth is that the criticisms of Mukherjee’s article on epigenetics (a term that I will go on to explain more fully, but which means “above genetics”) can’t be dismissed as jealous carping. In fact, they have a great deal of validity. The article can easily be read as yet another contribution to the hype about epigenetics—which, some have misleadingly alleged, rewrites the standard picture of how genes affect biological development and evolution.
Mukherjee—who won the 2011 Pulitzer for his book on cancer, The Emperor of All Maladies: A Biography of Cancer (at Columbia he is a professor of medicine specializing in cancer)—laid out clearly enough the basic question to which his piece was addressed. What is it that distinguishes a neuron from a muscle cell from a white blood cell, given that all of them, in a single individual, share the same genome? Or as he put it, “Why doesn’t a liver cell wake up one morning and find itself transformed into a neuron?”
The answer has been long recognized. During development, some genes get turned off while others might be turned on or ramped up, so that the different cell types execute different functions. The cells of a very early-stage embryo, just a few days old, possess all of their genetic potential: these “embryonic stem cells” are pluripotent, meaning that they can potentially develop into any of the tissues of the body. As development proceeds, they “differentiate” into specific cell types by the activation and deactivation of genes.