means that, at most, about 1040 such opportunities to mutate a gene that might ultimately produce a new protein fold could have occurred. Yet 1040 represents only a tiny fraction of 1077—the number of non-functional sequences corresponding to each protein fold of modest length (Fig. 10.11). Indeed, the fraction 1040 divided by 1077 equals 1 part in 1037, or 1 part in ten trillion times a trillion times a trillion, to be exact.
