In September of 2016, Mo et al. published an article in Science entitled “Spatiotemporal Microbial Evolution on Antibiotic Landscapes”. This landmark article describes a novel system for studying bacterial evolution. The findings elucidate the importance of antibiotic gradients in the emergence of antibiotic resistance in microbes and the many genetic pathways through which resistance can be achieved.
Among these findings was one particular observation: evolution is not simply survival of the fittest. The paper studied bacterial evolution using a system in which bacteria were inoculated into a large agar plate full of growth media. However, to move beyond their starting location to access more growth media, the bacteria had to evolve antibiotic resistance. At each stage, the concentration of local antibiotic increased ten-fold. One would imagine that only the most resistant bacteria would able to reach the front of the ever-expanding bacterial population and forge onwards into unexplored territory and greener pastures. However, this was not the case.
The authors observed a unique effect whereby many highly resistant mutants were trapped behind the progressing bacterial front. By virtue of being first, lesser-resistant bacteria had colonized ahead of highly resistant mutants, physically excluding them from expansion. This led the authors to conclude that the evolution and expansion of a bacterial population is not necessarily driven by its most evolved members.
Human society faces a similar phenomenon. Capitalism has been espoused as “survival of the fittest” for decades, yet this is a flawed truth. Fitness is surely required to survive in a capitalist society, but first-ness is also of great importance. High socioeconomic birth is accepted to predict success. Man, like microbe, is not governed purely by survival of the fittest.
Written By Adam Wade-Vallance
References may be found in the journal.