Dec 9, 2009

Antibiotics and Immunity to Evolution

Chuck MisslerBy Chuck Missler

Creationists often argue against evolution by noting that we cannot observe evolution occurring on a grand scale today. In response, evolutionary scientists like to point to bacteria.

Many scientists argue that evolution is happening all the time in bacteria. Bacteria, with their brief life cycles and their ability to reproduce vast multitudes of generations within a nice, short, observable time frame, give scientists a chance to demonstrate "evolution in a Petri dish". The ability of bacteria to develop resistance to antibiotics has been trumpeted as evidence of the driving force of evolution and the ability of gene swapping and mutations to make these organisms better able to survive.

However, while bacterial resistance to antibiotics is a reality, it falls far short of demonstrating the theory that all things descended from single-celled organisms billions of years ago. In fact, bacteria that become resistant to antibiotics often do so at the cost of their "relative fitness" and can lose pre-existing cellular functions.

Bacteria develop resistance to antibiotics in several ways:

Natural Resistance: Bacteria already naturally have some degree of protection against antibiotics, which they need when they run into these enemies, like penicillin, out in the great big world. This resistance only goes so far, and most bacteria will be killed off when faced with large doses of antibiotics for a significant period of time. The bacteria with the greatest resistance ability sometimes survive, though, going on to reproduce and make a plethora of antibiotic-resistant offspring. This is why doctors warn patients to take their entire antibiotics prescription and not stop halfway after the symptoms go away. Failing to take the entire course can allow the strongest bacteria to stick around and reproduce, paving the way for the superbugs we see today.

Of course, the resistance is already present in the bacterial gene pool. While these super strong bacteria offer a basic survival-of-the-fittest demonstration, their resistance to antibiotics is not an essentially new development and therefore doesn't prove evolution in a grander sense.

Horizontal Gene Transfer: Bacteria have a tremendous ability to swap genes with each other. This is vital for the health of bacteria, since they reproduce by binary fission (dividing into two parts) and do not benefit from the recombination of genes found in sexual reproduction. Antibiotic-resistant bacteria can exchange their genes with other bacteria, and thus pass on the ability to thumb their bacterial noses at modern medicine. Once again, the resistance is already there in the bacterial gene pool and is not an essentially new development.

Mutations: Mutations occur in bacteria in a variety of ways, including copy errors in the bacterial DNA and exposure to mutagens (chemicals or ionizing radiation) that affect bacteria's genetic material. Mutations have also enabled bacteria to resist antibiotics or chemical cleansers in some interesting, but not necessarily truly beneficial, ways.

For instance, some bacteria naturally produce the enzyme penicillinase, which they use to inactivate penicillin when they run into it in nature. If a bacterium has a problem with the gene that codes for shutting off the production of penicillinase, that bacterium will just keep producing the enzyme. This is great for the bacterium in the presence of a penicillin-based antibiotic regimen; in a human body filled with penicillin, this bacterium can survive to reproduce while the normal bacteria around it die. In normal life, though, the bacterium has a problem. It's putting a lot of energy into producing penicillinase, and because it can't turn the valve off, so to speak, it will have trouble doing all the other things it needs to do and will eventually penicillinase-produce itself to death.

Many bacteria develop resistance to antibiotics because something has gone wrong and they simply are not functioning properly. The loss of regulatory proteins is a big one. Some bacteria also lose full functioning in transport proteins. Transport proteins are necessary for bringing certain items into the cell. Bacteria that are resistant to Kanamycin get that way because they aren't correctly producing a transport protein, and therefore the Kanamycin can't get through the cell membrane into the bacterial cell to destroy it. If a transport protein is not functioning right, that means something is wrong with the cell, even if that lack of function does protect the bacteria from Kanamycin.

In short, broken genes can help bacteria survive in some circumstances, but we always find they do so at the expense of the general health of the bacteria. In a normal environment, these bacteria die off much more quickly than their normal, healthy relatives.

Gaining an Ability? Citrate in E coli: In 2008, evolutionary biologist Richard Lenski of Michigan State University in East Lansing found that a population of E coli, after thousands of generations, had started having trouble metabolizing glucose and instead had started to metabolize citrate. This was a big deal, and was touted as an important evolutionary step for the E coli. As New Scientist put it,

"…But sometime around the 31,500th generation, something dramatic happened in just one of the populations - the bacteria suddenly acquired the ability to metabolise citrate, a second nutrient in their culture medium that E. coli normally cannot use."
To the common reader, that sounds as though E coli mutated a brand new trait out of thin air. Especially since New Scientist goes on to say, "Indeed the inability to use citrate is one of the traits by which bacteriologists distinguish E. Coli from other species."

It is true that regular old E coli doesn't normally metabolize citrate. However, it does have the ability to do so under specific conditions. In August 1998, the Journal of Bacteriology published an article on the ability of E coli to convert citrate to acetate and succinate under anoxic conditions (the absence of oxygen) when an oxidizable cosubstrate like glucose is present. In other words, if sugar is present and oxygen isn't, E coli does have the capacity to "eat" citrate.

Discovering exactly what happened to "up" this ability is up to Dr. Lenski's team. He has samples of E coli populations from thousands of generations over the years, and he can pinpoint the specific changes that led to make E coli's already existing citrate carrier expand its horizons.

We just find it interesting that these citrate-munching E coli have also lost a lot of their ability to eat glucose, their normal food.

Evolutionists argue that evolutionary change doesn't always have to be a drive upward. They say that evolutionary change can offer benefits at the same time as losing other useful functions. That's fine. Except that we never see any examples of truly upward "change." If there is a new or improved ability in an organism, we find that it was always tucked away there in the genetic code. Otherwise, "new" traits tend to come with a loss of information, a loss of function, a mistake, an error that might temporarily offer some benefit to the creature at hand, but in the long run harms it. The man with no esophagus will have a hard time getting sick from a foodborne illness, but few people will argue that living by feeding tube is a long-term beneficial "adaption." Evolutionists keep trying to argue that similar losses or defects offer beneficial adaption, but all we see in these mutations is net deterioration.

In all this, we find that bacteria are still bacteria. They are not developing new organelles that were not previously present. For good or bad, fully functioning or not, they just continue to behave like bacteria. We say, aside from thousands of years of genetic weakening, they are still doing what God designed them to do.

Related Links

Bacteria Make Major Evolutionary Shift In The Lab - New Scientist
The Escherichia coli Citrate Carrier CitT - Journal of Bacteriology
Is Bacterial Resistance to Antibiotics an Appropriate Example of Evolutionary Change? - Creation Research Society Quarterly
SuperBugs Not Super After All -
Learn the Bible in 24 Hours - Chuck Missler (Book)