The Gene: An Intimate History - Siddhartha Mukherjee Page 0,60

experiments putrefied twin research so effectively, pickling the entire field in such hatred, that it would take decades for the world to take it seriously.

The second contribution of the Nazis to genetics was never intended as a contribution. By the mid-1930s, as Hitler ascended to power in Germany, droves of scientists sensed the rising menace of the Nazi political agenda and left the country. Germany had dominated science in the early twentieth century: it had been the crucible of atomic physics, quantum mechanics, nuclear chemistry, physiology, and biochemistry. Of the one hundred Nobel Prizes awarded in physics, chemistry, and medicine between 1901 and 1932, thirty-three were awarded to German scientists (the British received eighteen; the Americans only six). When Hermann Muller arrived in Berlin in 1932, the city was home to the world’s preeminent scientific minds. Einstein was writing equations on the chalkboards of the Kaiser Wilhelm Institute of Physics. Otto Hahn, the chemist, was breaking apart atoms to understand their constituent subatomic particles. Hans Krebs, the biochemist, was breaking open cells to identify their constituent chemical components.

But the ascent of Nazism sent an immediate chill through the German scientific establishment. In April 1933, Jewish professors were abruptly evicted from their positions in state-funded universities. Sensing imminent danger, thousands of Jewish scientists migrated to foreign countries. Einstein left for a conference in 1933 and wisely declined to return. Krebs fled that same year, as did the biochemist Ernest Chain and physiologist Wilhelm Feldburg. Max Perutz, the physicist, moved to Cambridge University in 1937. For some non-Jews, such as Erwin Schrödinger and nuclear chemist Max Delbrück, the situation was morally untenable. Many resigned out of disgust and moved to foreign countries. Hermann Muller—disappointed by another false utopia—left Berlin for the Soviet Union, on yet another quest to unite science and socialism. (Lest we misconstrue the response of scientists to Nazi ascendency, let it be known that many German scientists maintained a deadly silence in response to Nazism. “Hitler may have ruined the long term prospects of German science,” George Orwell wrote in 1945, but there was no dearth of “gifted [German] men to do necessary research on such things as synthetic oil, jet planes, rocket projectiles and the atomic bomb.”)

Germany’s loss was genetics’ gain. The exodus from Germany allowed scientists to travel not just between nations, but also between disciplines. Finding themselves in new countries, they also found an opportunity to turn their attention to novel problems. Atomic physicists were particularly interested in biology; it was the unexplored frontier of scientific inquiry. Having reduced matter into its fundamental units, they sought to reduce life to similar material units. The ethos of atomic physics—the relentless drive to find irreducible particles, universal mechanisms, and systematic explanations—would soon permeate biology and drive the discipline toward new methods and new questions. The reverberations of this ethos would be felt for decades to come: as physicists and chemists drifted toward biology, they attempted to understand living beings in chemical and physical terms—through molecules, forces, structures, actions, and reactions. In time, these émigrés to the new continent would redraw its maps.

Genes drew the most attention. What were genes made of, and how did they function? Morgan’s work had pinpointed their location on chromosomes, where they were supposedly strung like beads on a wire. Griffith’s and Muller’s experiments had pointed to a material substance, a chemical that could move between organisms and was quite easily altered by X-rays.

Biologists might have blanched at trying to describe the “gene molecule” on purely hypothetical grounds—but what physicist could resist taking a ramble in weird, risky territory? In 1944, speaking in Dublin, the quantum theorist Erwin Schrödinger audaciously attempted to describe the molecular nature of the gene based on purely theoretical principles (a lecture later published as the book What Is Life?). The gene, Schrödinger posited, had to be made of a peculiar kind of chemical; it had to be a molecule of contradictions. It had to possess chemical regularity—otherwise, routine processes such a copying and transmission would not work—but it also had to be capable of extraordinary irregularity—or else, the enormous diversity of inheritance could not be explained. The molecule had to be able to carry vast amounts of information, yet be compact enough to be packaged into cells.

Schrödinger imagined a chemical with multiple chemical bonds stretching out along the length of the “chromosome fiber.” Perhaps the sequence of bonds encoded the code script—a “variety of contents compressed into [some] miniature code.” Perhaps the order of beads on the string carried