Dr. Michael Egnor, of SUNY Stony Brook and the Discovery Institute, doesn’t think that evolution is relevant to trying to figure out how to combat the spread of antibiotic resistance. The interesting areas of research, he believes, lie in other areas of biology:
The important medical research on antibiotic resistance in bacteria deals with how the mutations that give rise to resistance arise, exactly what those mutations are and how they work, and what can be done to counteract them. The important medical research involves genetics, molecular biology, and pharmacology. Darwin’s theory is of no substantive value to the research because, as Mr. Dunford admits, there is no difference between antibiotic resistant bacteria that emerge through artificial intelligent selection and antibiotic resistant bacteria that emerge through natural selection. Antibiotic resistance is a phenomenon that occurs because there are often a few bacteria in a large population of bacteria that have a mutation that renders them less sensitive to the antibiotic. These bacteria that aren’t killed by the antibiotic eventually outnumber bacteria that are killed by the antibiotic. Survivors survive. Does this mundane observation really help Mr. Dunford understand things he may not have otherwise understood? It certainly doesn’t advance medical research in any meaningful way. New insights into genetics, molecular biology, and pharmacology do advance medical research.
I realize that I’m just begging for Dr. Egnor to take what I say out of context again, but he is not entirely wrong. If I was working on ways to fight antibiotic resistance, I would certainly want to focus more on the molecular mechanisms that are involved in the development of resistance than on the question of how resistance spreads through a population of bacteria after it appears.
The fact of the matter is that we already have a very good idea of how antibiotic resistance spreads through a population of bacteria.
Bacteria reproduce at a very high rate. In bacteria, as in all other living organisms on this planet, the process of reproduction is not perfect. The new copy of the bacterial DNA is not always exactly the same as the old one. Sometimes, the errors in reproduction have no effect on the bacteria. Sometimes, the errors in reproduction kill the bacteria. Sometimes, the errors in reproduction result in the bacteria gaining or losing the ability to do certain things. Because these errors take place in the DNA, they will be passed on (imperfectly) as the bacteria continue to reproduce.
If the environment that the bacteria live in changes, and bacteria that have an “error” that allows them to do something new become much more likely to reproduce than bacteria without the “error”, the entire population is going to change very quickly. The bacteria that have the “error” will produce more bacteria that have the “error”. The bacteria that lack the “error” will produce fewer bacteria without it. Soon, the vast majority of the bacteria in the population will have the “error”.
Antibiotics change the environment that bacteria live in. Bacteria that have DNA copying mistakes that result in them being better able to survive and reproduce in the presence of the antibiotic will produce more bacteria like themselves. After a relatively small number of generations, the vast majority of bacteria in the population will be resistant to the
That’s a relatively simple version of the explanation, of course. I’ve left out quite a few details. Still, it’s a pretty reasonable summary of our understanding of how a new trait (in this case, antibiotic resistance) can spread through a population (in this case, bacteria).
It’s also a reasonable summary of the process of evolution through the mechanism of natural selection. This is the mechanism that was first outlined in the Darwin and Wallace papers in 1858, and it’s the process that Darwin discussed in depth in The Origin of Species.
If researchers are focusing more of their attention on the question of how resistance arises in the first place than they are on how resistance spreads through a population after it arises, it’s because we have a reasonably good understanding of how resistance spreads. In science, the interesting questions are the ones that still need to be answered.
The fact that a question has been answered does not mean that either the question or the answer are unimportant. In the case of antibiotic resistance, both remain extremely important. It’s our understanding of evolution that informs the measures that doctors need to take to reduce the risk of developing new strains of multiple drug-resistant bacteria. It’s our understanding of evolution that leads us to restrict the veterinary use of certain antibiotics in order to better preserve their effectiveness when used by people. The importance of evolution in this case is not in any way reduced simply because we understand how it works.
In fact, we understand how evolution works so well that we can actually use evolution as a tool to aid in researching other questions about antibiotic resistance. In the research project that kicked off this latest burst of Egnorian rhetoric, scientists used natural selection to obtain a population of antibiotic-resistant bacteria. They then studied those bacteria to figure out what made them resist the antibiotic. The importance of evolution in this case in not reduced simply because we understand it well enough to make it work for us.
Dr. Egnor apparently wants to object to all of this because it’s not one of the areas of evolutionary biology that he finds objectionable:
Antibiotic resistance is irrelevant to the inference to design or to chance in biology, and therefore it is irrelevant to the debate over Darwin’s theory.
That assertion is very difficult to justify. “Darwin’s theory” is just what I outlined above: if a heritable trait makes it more likely that those who possess it will successfully reproduce, the trait will spread through the population. That process drives the spread of antibiotic resistance. That may not be something that Egnor objects to, but it’s still part and parcel of “Darwin’s theory”.