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Publisher: Bluejack

May, 2009 : Feature:

Sneezing Your Way Through Selection

Or, Sex and the Single Bug

Concepts of "The Past" are so ubiquitous today that many take awareness of past living conditions for granted as if the way people think is the way they have always thought. But for most of human history historical change was basically an unknown phenomenon. Not that the people of Rome didn’t know there were civilizations before the Empire—they did. They were aware of their own beginning with celebrations on the 21st of April dating back to around 753 BC, aka 1 ab Urbe condita. Some say they even had predictions for when the Empire would fall, recognizing their own essentially ephemeral position in the firmament.

But the level of technology for all civilizations post and prior was, for them, static. Roman citizens could not conceive of a time different in the basics from their own. Past, present and future stretched to eternity in understandable sameness. If you were transported to Rome in 15 March 44 BC you would understand most of what surrounded you, but Caesar could certainly not conceive of your world–if he could have found the time on that particular day to ponder it.

When we are judged by future generations or by alien diplomats (or alien archeologists), having discovered and acted upon our origins will almost certainly be a benchmark of our journey to maturity. So it is so surprising to me that here in the technologically savvy West many in positions of power do not accept the basic tenets of biology and origins. And by power-wielders I do not mean the one sitting at 1600 Pennsylvania Avenue (or 24 Sussex Drive or the Élysée Palace or Number 10 Downing Street). I mean instead the ones closer to home, the ones with direct effects on your personal needs: people as different and disparate as farmers and doctors.

Think of yourself sitting on a vast plain, lost within a forest of menhirs standing about like enigmatic dominos of effect and consequence ready to tumble to cause. One falls, and many others may fall as well, sometimes with outcomes of no real importance and other times with profound and even dire result. Unfortunately we are not responsible for the all the choices made affecting the stability of the menhirs around us. But we are certainly positioned to feel the direct effect of their fall as well as butterfly effect emanations from each. One of those choices is all about evolution and origins.

Details of human origin may be obfuscated by the barriers of deep time, but we are aware that the road was an evolutionary one. Like our Roman forbears, we have a long enough generation span that we cannot directly perceive our own evolutionary changes. But once having understood the kinship all organisms share through the Biological Imperative (i.e. Reproduce!) we now know what to look for in our many taxonomic cousins.

As we turn our gaze to the microbial world, we find ourselves in an evolutionary dance with bacteria. Both benevolent and malevolent, bacterial populations profoundly influence our daily lives. Some we need to stay healthy, and some attack us. When they do, and attempt to abscond with our hard-gained resources, we see doctors.

Bacteria are single-celled prokaryotic organisms. They do not have male and female members, nor do they have a nucleus to hide and protect their DNA. We, on the other hand, have both. Asexual organisms such as bacteria do not reap the benefits of sexual reproduction as far as recombination of their DNA is concerned. Eukaryotic organisms such as ourselves, truffles, or turbots, undergo sexual reproduction and thus a mixing of genetic material between two members of the same species. The newly minted genotypes are then tossed into the world and undergo selective pressure against others competing for the same resources and environment. Evolution can be directly measured as changes in gene frequency from one generation to the next.

Bacteria are asexual and undergo fission, splitting a parent cell into two daughter cells. At first glance you would think that these daughter cells would be genetically identical to the parent, generation upon fifteen-minute generation. Evolution would be slow at best in organisms without recombination, relying on point mutation and a slow dissemination of those with desirable new traits to increase through the population. But evolution has provided bacteria with tricks, to wit: conjugation, transduction and transformation—tricks of which the decision makers among us are often abysmally unaware.

That was of course a thinly veiled dig at those that still do not accept the fact of evolution. It’s really not a harmless quirk to sideline evolutionary processes when decisions dependa on it. If your Great Aunt Daisy wants to tell you how distasteful it is to imagine apes in your distance past smile, nod, and chew another sugar cookie. If your doctor tells you evolution has no place in medical considerations, run.

Bacteria are bathed in antibiotics. Why this is so, I will come back to shortly. Suffice it to say here that since they are, and since an antibiotic wash is detrimental to bacterial health, populations of bacteria are under a constant selective pressure. Since we define evolution as changes in gene frequency from one generation to the next, the gene frequencies pertaining to antibiotic resistance are logically on the increase.

If bacteria conducted their private affairs associated with reproduction on a strictly parent/daughter cell line of descent, the spread of antibiotic resistance in the populations around us would be slow. As it is, bacteria’s tricks of conjugation, transduction and transformation not only mimic our ability as eukaryotes to reshuffle our DNA, but give them access to a DNA library of a kind to which we higher organisms have no counterpart.

Bacteria are unconcerned with anything so parochial as species barriers. Genetic information may be liberally shared between different bacterial species in a free-wheeling orgy of DNA exchange. Without invoking tedious and word-gobbling definitions for conjugation, transduction and transformation, let me simply say that with these mechanisms bacterial DNA, and the encoded traits encoded therein, can be shared and incorporated. So the higher the frequency of antibiotic resistance genes in a population, the faster the rate of dissemination of the trait to new bacterial cell lines.

Not only are the little critters fast enough to beat our efforts at discovering new antibiotics, they are also adept at using us to spread them around. Infected, we become transportation machines for new bacteria that have been vetted by the conditions inside our bodies. Take your antibiotics, and you subject your population of infective bacteria to selective pressure where the most resistant individuals survive an environment of increasing toxicity. Don’t finish your antibiotic prescriptions and you tweak them into stronger positions of battle because just enough antibiotics to make you feel better is just enough to leave them resistant instead of dead. Then every time you sneeze, out they go, carrying along in their DNA the ability to thwart our best efforts at medical defense.

But it’s not just you who needs to carefully consider your antibiotic use. Doctors who prescribe antibiotics for viral infections “just in case” are adding to the rapidity with which bacteria can develop resistance by exposing them unnecessarily. And if a doctor that tells you that natural selection is a myth and not the mechanism for the development of antibiotic resistance . . . well, run and find a new doctor. Likewise, farmers who flood the environment by feeding, spraying, and injecting their livestock with an indiscriminate plethora of antibiotics for “health and production” reasons are really helping no one but the hordes of E. coli and others swarming around (and in) all of us.

The face of antibiotic resistance is an ugly one. Flesh eating bacteria are resistant to broad ranges of antibiotics and some are so difficult to address with drugs that amputation is the only treatment. There are a small number of bacteria that can be culprits for this disease, and all of them have developed frightening levels of resistance. And where you might contract such a disease is not just where bacteria congregate, it’s where bacteria congregate and are subjected to constant selective pressures: hospitals.

The average human lifespan during the Roman Empire has been estimated across a broad range, but no estimates reach 40, and most do not exceed 35. Even as recently as the 1800s the average human life expectancy did not surpass 40 years. Alexander Fleming’s discovery of antibiotics in 1928 changed the average life expectancy in a grand leap, but he also foresaw, quite early on, the danger resistance developing with the misuse of antibiotics.

There are many predictions for disaster and the fall from Mayan calendars to the latest nomination for antichrist. But the loss of viable antibiotics is a real threat that lives as close as your bathroom medicine cabinet and around the drain of your shower stall. It’s no longer enough for an individual to do the right thing; all of us must realize the social contract and act in unison. Our ancestors were not aware of the past. Tomorrow’s judges may describe us as oblivious to the future—the perpetrators of our own demise.


Copyright © 2009, Rob Furey. All Rights Reserved.

About Rob Furey

Dr. Rob Furey worked on his PhD in Gabon, West Africa, on social spiders. He has returned to his study site several times for his own research, with students and once as a forest guide for a natural history film crew from the UK. He has faced down cobras, retreated from army ants and slept on open wooden platforms in African swamps. Later he went to French Amazonia to work on another social spider species. Not only did he spend time with the spiders, but he watched a gunfight between gold prospectors and French army troops while he ate a meal of roasted tapir. Since then Rob has returned to the tropics several times, usually with students. He spent time as a student himself attending Clarion West. He has published a couple of stories in anthologies since then in addition to articles for dusty tomes on arcane spider behavior. He is currently part of the charter faculty at Harrisburg University, the first new private university in Pennsylvania in over 100 years.

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