Mutation Stasis
Mutation Stasis
By Richard William Nelson
To prove that Darwin was not wrong, David Quammen, in the leading November 2004 National Geographic article entitled “Was Darwin Wrong?” used antibiotic resistance through mutation as proof. Quammen explains that the bacteria by natural selection “acquire resistance to drugs that should kill them. They evolve. There’s no better or more immediate evidence supporting the Darwinian theory than this process of forced transformation among our inimical germs.”
Underlying the role of mutations lies the question, are mutations just nature’s way of adapting to the environment and not evidence of evolution? In 1943, published in a paper entitled “Mutations of Bacteria from Virus Sensitivity to Virus Resistance,” microbiologist Salvador Luria, biophysicist Max Delbrück, and bacteriologist and geneticist Alfred Hershey discovered that mutations occur at a constant rate. In 1969, they were awarded the Nobel Prize in Physiology and Medicine “for their discoveries concerning the replication mechanism and genetic structure of virus.”
With constant mutations, comes the next question, is the resistance a product of new mutations? Experimenting with the antibiotic streptomycin at the University of Wisconsin-Madison in the early 1950s, Joshua Lederberg, along with his graduate student Norton Zinder, demonstrated that bacteria never previously exposed to streptomycin was already resistant to the antibiotic.
Later in the twentieth century, scientists at the University of Alberta revived bacteria from members of the historic “Franklin Expedition” who mysteriously perished in the Arctic nearly one-hundred and fifty years ago in 1845. The scientists were surprised to discover that the bacteria recovered from the intestines of the explorers had the same level of antibiotic resistance as modern bacteria. In a 1990 headline story in the Canadian Sunday Herald entitled “Ancient Bacteria Revived,” Ed Struzik reported that not “only are the six strains of bacteria almost certainly the oldest ever revived … three of them also happen to be resistant to antibiotics. In this case, the antibiotics clindamycin and cefoxitin, both of which were developed more than a century after the men died, were among those used.” The recovered bacteria had resistance even before encountering the antibiotics. Resistance in these organisms was not a product of new mutations in response to antibiotic exposure. Resistance was preexistent.
More recently, preexistent resistance in bacteria has also been observed in viruses and insects. After studying the AIDS virus in 2000, theoretical biologists Ruy M. Ribeiro and Sebastian Bonhoeffer, from the Wellcome Trust Centre for the Epidemiology of Infectious Diseases, published an article in the Proceedings of the National Academy of Sciences of the United States of America about their bservation of the same phenomena in viruses. Resistance was preexistent and was not acquired by mutations. Ribeiro and Bonhoeff er concluded, “the key to drug resistance lies in the diversity of the viral population at the start of therapy.”
In examining viral models to determine whether the antimicrobial resistance was acquired during treatment through mutation or was preexistent, Ribeiro and Bonhoeffer concluded that the resistance was “most likely caused by the preexistence of resistant mutants.” Resistance did not originate from environmental pressures. The resistance was not new, nor was resistance acquired through any novel mutation mechanism not previously inherent in the organism.
Even in insects, resistance existed prior to the introduction of insecticides. In 1978, in a Scientific American article entitled “The Mechanisms of Evolution,” evolutionary geneticist Francisco Ayala wrote: Insect resistance to a pesticide was fi rst reported in 1947 for the housefly [Musca domestica] with respect to DDT [synthetic pesticide]. Since then, resistance to one or more pesticides has been reported in at least 225 species of insects and other arthropods. Th e genetic variants required for resistance to the most diverse kinds of pesticides were apparently present in every one of the populations exposed to these man-made compounds. While bacterial resistance through the mutation model is a logical mechanism for evolution, the reality is the bacteria have remained bacteria, the virus has remained a virus, and the fly has remained a fly. Preexistent genetic variants determine the range of mutations. In 1977, Pierre-Paul Grassé, president of the French Academy of Sciences, observed, “bacteria, the study of which has formed a great part of the foundation of genetics and molecular biology … stabilized a billion years ago.”
The question is whether the mutations are the “raw material for evolution” or nature’s means for the microbes to adapt to the environment. Reflecting on the interpretation of mutations, Grassé wondered, “What is the use of their unceasing mutations if they do not change?” Grassé concludes, “the mutations of bacteria and viruses are merely hereditary fluctuations around a median position; a swing to the right, a swing to the left, but no final evolutionary effect.”
Acknowledging that while novel mutations do occur, molecular biologist Soren Lovtrup, of the University of Goterborg in Sweden, writes, “micromutations do occur, but the theory that these alone can account for evolutionary change is either falsified, or else it is an unfalsifiable, hence metaphysical theory.” Lovtrup continues by lamenting the core of evolution’s central dogma: I suppose that nobody will deny that it is a great misfortune if an entire branch of science becomes addicted to a false theory. But this is what has happened in biology.… I believe that one day the Darwinian myth will be ranked the greatest deceit in the history of science. When this happens many people will pose the question: How did this ever happen?”
Are the mutations directed or undirected? At the core of the central dogma is the accumulation of novel mutations. For Darwin, evolution was a directed process. In The Origin of Species, Darwin wrote, “I was so convinced that not even a stripe of colour appears from what is commonly called chance.” Acquiring directed variations is the kingpin in Darwin’s theory. Darwin envisioned that “all spontaneous variations in the right direction will thus be preserved.”
Since the origin of new variations is mutation dependent, does the evidence favor directed or undirected (random) mutations? In an article published in Nature in 1988, Harvard University molecular biologists John Cairns, Julie Overbaugh, and Stephan Miller reconfirmed the Luria–Delbrück experiment, demonstrating the undirected nature of bacterial mutations: “As the result of studies of bacterial variation, it is now widely believed that mutations arise continuously and without any consideration for their utility.”
To further investigate whether mutations are directed or random, the Cairns team suggested a series of experiments to detect directional mutations. In 2002, Susan Slechta of the University of Utah and Jing Liu of the Swedish Institute for Infectious Disease Control published a research paper using Cairn’s team’s suggestions and discovered no evidence for directional mutations.
Continuing the search for directional mutations, researchers Monica Sala and Simon Wain-Hobson from the Pasteur Institute in France examined eighty-five sets of proteins from viruses that are known to infect bacteria, plants, and mammals. The results, published in a 2000 paper entitled “Are RNA Viruses Adapting or Merely Changing?” revealed that even though viruses mutate rapidly, the mutations occur randomly and are not directed to adapting to the environment.
To the question, can microorganisms change over time? The answer is yes. To the next question, are they “purposefully evolving”? The answer is no. Genetic mutations responsible for antibiotic resistance in bacteria do not arise from the need of an organism to develop such resistance. As evolutionist, Douglas Futuyma explains, “the adaptive ‘needs’ of the species do not increase the likelihood that an adaptive mutation will occur; mutations are not directed toward the adaptive needs of the moment…. Mutations have causes, but the species’ need to adapt isn’t one of them.”
From the current scientific evidence, two key factors emerge in reference to mutations. First, a range of potential favorable mutations is an inherent characteristic of an organism, and second, these potential mutations occur in a random fashion unrelated to the environmental conditions. This current evidence contradicts Darwin’s theory of the directed and purposeful evolution of species—that forms the Tree of Life.
