• Escape of the Pathogens
• Antibiotic resistance
• HIV

The Escape of the Pathogens: An Evolutionary Arms Race (2 of 2)

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Every day we come into contact with millions of bacteria and viruses. Some are harmful and others are beneficial, while the rest have no apparent effect on our health. When harmful microorganisms enter our bodies, a battle ensues.

Rapid reproduction and natural selection
Because bacteria and viruses reproduce rapidly, they evolve rapidly. These short generation times—some bacteria have a generation time of just 15 minutes—mean that natural selection acts quickly. In each pathogen generation, new mutations and gene combinations are generated that then pass through the selective filter of our drugs and immune response. Over the course of many pathogen generations (a small fraction of a single human lifetime), they adapt to our defenses, evolving right out from under our attempts to rid ourselves of them.

Applying our knowledge of evolution
But that doesn’t mean that we should stop trying to win these battles. By understanding these pathogens as evolving entities, subject to the same processes of evolution that we can study in fruit flies or the fossil record, we may be able to identify ways to slow their progress.

	Lesson plans for teaching about the arms race