We do this in our homes, hospitals, backyards, farm fields and even, in some cases, forests when we use antibiotics, pesticides, herbicides. and any other “herbicide”. And the effects are always predictable.
Recently, Michael Baym and colleagues at Harvard University built a giant Petri slab, or “gypsum board,” divided into a series of columns. Then, Baym adds agar, which is both food and a habitat for microorganisms. The outer column on each side of the megaplate contains the jelly and nothing else. Moving inside, each subsequent column is impregnated with increasingly high concentrations of antibiotics. Baym then released bacteria at both ends of the megaplate to test whether they had evolved resistance to antibiotics.
Bacteria do not have genes for antibiotic resistance; They entered the super tower like defenseless sheep. And if jelly is the pasture for these bacterial “sheep”, then antibiotics are wolves. The experiment mimics the way we use antibiotics to control disease-causing bacteria in the body. It mimics the way we use herbicides to control weeds on our lawns. It mimics each and every way that we try to hold back nature every time it floods our lives.
The law of natural selection would predict that as long as genetic variation can occur, through mutation, bacteria will eventually be able to develop resistance to antibiotics. But it could take years or longer. It can take a long time for the bacteria to run out of food before they develop the ability to infect antibiotic columns, which are filled with wolves.
It doesn’t take many years. It takes 10 or 12 days.
Baym repeated the experiment. It happens the same every time. Bacteria fill the first column and then slow down for a short time, before one and then many lines evolve resistance to the next highest concentration of antibiotics. This continued until a few of the strains evolved resistance to the highest concentrations of antibiotics and poured into the final column, like water on a dike.
Accelerated, Baym’s experiment was horrifying. It’s also beautiful. Its horror lies in the speed with which bacteria can go from defenseless to indestructible compared to our strength. Its beauty lies in its ability to predict the outcome of an experiment, when it comes to understanding the laws of natural selection. This predictability allows for two things: It allows us to know when resistance can be expected to develop, whether between bacteria, aphids or some other group of organisms; it also allows us to manage the river of life to make the development of resistance less likely. An understanding of the laws of natural selection is key to human health and happiness and, frankly, to our species’ survival.
There are other biological laws of nature with similar consequences. Regional species laws regulate the number of species that live on a particular island or habitat as a function of its size. This law allows us to predict where and when species will go extinct, as well as where and when they will evolve again. Corridor laws govern which species will migrate in the future as the climate changes and how. The Law of Escape describes the ways that species thrive when they are free from pests and parasites. The escapism explains some of the successes of humans relative to other species and how we are able to achieve such extraordinary abundance relative to other species. The law outlines some of the challenges we will face in the years to come as our ability to get rid of (from pests, parasites and the like) is less. The law of relevance governs where species, including humans, can live and where we can successfully live in the future as the climate changes.
