The Gene: An Intimate History - Siddhartha Mukherjee Page 0,191

a complicated recipe!”—and then rest assured that someone will not learn to understand or hack or manipulate that recipe in some deliberate manner.

When scientists underestimate complexity, they fall prey to the perils of unintended consequences. The parables of such scientific overreach are well-known: foreign animals, introduced to control pests, become pests in their own right; the raising of smokestacks, meant to alleviate urban pollution, releases particulate effluents higher in the air and exacerbates pollution; stimulating blood formation, meant to prevent heart attacks, thickens the blood and results in an increased risk of blood clots to the heart.

But when nonscientists overestimate complexity—“No one can possibly crack this code”—they fall into the trap of unanticipated consequences. In the early 1950s, a common trope among some biologists was that the genetic code would be so context dependent—so utterly determined by a particular cell in a particular organism and so horribly convoluted—that deciphering it would prove impossible. The truth turned out to be quite the opposite: just one molecule carries the code, and just one code pervades the biological world. If we know the code, we can intentionally alter it in organisms, and ultimately in humans. Similarly, in the 1960s, many doubted that gene-cloning technologies could so easily shuttle genes between species. By 1980, making a mammalian protein in a bacterial cell, or a bacterial protein in a mammalian cell, was not just feasible; it was, in Berg’s words, rather “ridiculously simple.” Species were specious. “Being natural” was “often just a pose.”

The genesis of a human from genetic instructions is indubitably complex, but nothing about it forbids or restricts manipulation or distortion. When a social scientist emphasizes that gene-environment interactions—not genes alone—determine form, function, and fate, he is underestimating the power of master-regulatory genes that act nonconditionally and autonomously to determine complex physiological and anatomical states. And when a human geneticist says, “Genetics cannot be used to manipulate complex states and behaviors because these are usually controlled by dozens of genes,” that geneticist is underestimating the capacity of one gene, such as a master regulator of genes, to “reset” entire states of being. If the activation of four genes can turn a skin cell into a pluripotent stem cell, if one drug can reverse the identity of a brain, and if a mutation in a single gene can switch sex and gender identity, then our genomes, and our selves, are much more pliable than we had imagined.

Technology, I said before, is most powerful when it enables transitions—between linear and circular motion (the wheel), or between real and virtual space (the Internet). Science, in contrast, is most powerful when it elucidates rules of organization—laws—that act as lenses through which to view and organize the world. Technologists seek to liberate us from the constraints of our current realities through those transitions. Science defines those constraints, drawing the outer limits of the boundaries of possibility. Our greatest technological innovations thus carry names that claim our prowess over the world: the engine (from ingenium, or “ingenuity”) or the computer (from computare, or “reckoning together”). Our deepest scientific laws, in contrast, are often named after the limits of human knowledge: uncertainty, relativity, incompleteness, impossibility.

Of all the sciences, biology is the most lawless; there are few rules to begin with, and even fewer rules that are universal. Living beings must, of course, obey the fundamental rules of physics and chemistry, but life often exists on the margins and interstices of these laws, bending them to their near-breaking limit. The universe seeks equilibriums; it prefers to disperse energy, disrupt organization, and maximize chaos. Life is designed to combat these forces. We slow down reactions, concentrate matter, and organize chemicals into compartments; we sort laundry on Wednesdays. “It sometimes seems as if curbing entropy is our quixotic purpose in the universe,” James Gleick wrote. We live in the loopholes of natural laws, seeking extensions, exceptions, and excuses. The laws of nature still mark the outer boundaries of permissibility—but life, in all its idiosyncratic, mad weirdness, flourishes by reading between the lines. Even the elephant cannot violate the law of thermodynamics—although its trunk, surely, must rank as one of the most peculiar means of moving matter using energy.

The circular flow of biological information—

—is, perhaps, one of the few organizing rules in biology. Certainly the directionality of this flow of information has exceptions (retroviruses can pedal “backward” from RNA to DNA). And there are yet-undiscovered mechanisms in the biological world that might change the order or the components of information flow in living systems