She sat in one of the workstation booths provided for personal use, making notes from the latest transmissions from Charlie Hu and Pieter Naarmegen on Earth concerning their biological and geological findings, with comments contributed by Emil Farzhin’s group back on Dione. There seemed no escaping the conclusion that the genetic codes that enabled such rapid adaptation to occur had to be present already in the genome. And as already postulated, the most likely mechanism for getting them there, and propagating them quickly through a population, was infection. In itself, however, simply admitting foreign genetic information into cells somewhere in the body wasn’t enough. To become a fixed trait in a species, it would have to somehow find its way to the reproductive cells and there be incorporated into the germ DNA to be transmissible to subsequent generations. Farzhin had put forward the suggestion that in fact a mechanism of precisely this nature had been known for a long time, which Terran science had read as reactions to a new class of virus.
It sometimes happened that strong environmental pressures caused cells to begin manufacturing certain proteins on a modest scale, but not a high enough rate to disrupt the cell’s normal functioning—unlike “real” pathogenic viruses that caused sickness by killing cells. These packages then budded off through the cell membrane wrapped in a blanket of host protein—the ideal camouflage for navigating the hazards of a hostile immune system—and on arrival at the germ cells were written “backward” into the DNA there by the reverse transcriptase enzyme, tailor-made for the purpose, but whose reason for existence had been baffling researchers since the previous century. In short, Farzhin maintained, the messenger proteins that were the products of some sickness conditions that had been read instead as antibodies to nonexistent viruses. In other words, results were taken to be causes.
The suggestion that alterations to the genome could be triggered by forces in the environment rather than coming about purely through chance flew in the face of what had been unquestionable biological dogma—if not smacking of open Lamarckism, then running perilously close to it. But that was of little consequence to the Kronians, who had seen too many of Earth’s once-sacred doctrines come apart in any case.
One of Vicki’s favorite examples was the mutations in some strains of bacteria that confer a resistence to mycin antibiotics—at one time widely acclaimed as demonstrating “evolution in action.” Of course, the theory had never held that individuals evolve. A cat lives its life and dies with the same genetic endowment that it was born with. What was believed to evolve with the passage of time—either gradually, or in jumps, or however—and get passed down from generation to generation was the accumulating information that makes up the genome. The form exhibited by a species was seen as snapshot of that information expressing itself at the point reached at the time in question. On average, therefore, every meaningful step along the way added some finite amount of information to the growing genome. Or to put it another way, to be considered a meaningful contribution to the evolutionary process, a mutation would have to add genetic information that hadn’t been there previously.
But every point mutation that had been studied by generations of researchers turned out to have reduced genetic information, not increased it. In the case of antibiotic resistance, the mutations responsible acted in such a way as to lose the specific shape of the docking site on the bacterial ribosome that enabled a molecule of the drug to attach itself there and render the bacterium dysfunctional. The information was lost that was needed to make the fit a precise one. Hence, “evolution in action” turned out to be nothing that could be construed as contributing to the process at all. As in business, where you can’t accumulate money by losing it all the time.
Wherever it came from, adaptive genetic information seemed to be already there, in the genome, waiting for cues from the outside to activate it. In another example that Vicki had studied, experimenters had bred a deficient strain of bacteria that normally live on the milk sugar lactose, lacking in the enzymes necessary to metabolize it. But if two particular mutations happened to occur together, they would operate in conjunction to create a path by which an alternative sugar could be metabolized instead. According to calculation, it should have taken about a hundred thousand years for one of the double mutations to occur. In fact, over 40 instances were observed within a few days. But this happened only when the alternative sugar was present in the culture. Somehow, the presence of the needed nutrient was triggering the mutations necessary for it to be utilized. This and many other examples like it had been known long before the Athena catastrophe hit Earth, but they had provoked such outrage and controversy among defenders of the faith as to be denied or ignored.