Understanding Evolution: What is Natural Selection?

“When it was introduced in the 1940s, penicillin was a miracle drug, especially effective at curing infections caused by the bacterium Staphylococcus aureus ("staph"). In 1941, the drug could wipe out every strain of staph in the world. Now, seventy years later, more than 95% of staph strains are resistant to penicillin.” — Dr. Jerry Coyne, "Why Evolution is True"

-----------------------

In "Why Evolution is True", Dr. Coyne used this example in the chapter entitled, “The Engine of Evolution.” The engine he’s referring to is none other than natural selection, and this little insight regarding the adaptability (evolution) of Staphylococcus aureus is excellent evidence for the theory of evolution by natural selection. It’s my go-to “proof,” if you will, when someone asks me to provide proof of evolution because (a) it’s simple and easy to understand, (b) it definitively shows that an organism can adapt to a new environment (in this case, a human body injected with penicillin), (c) it doesn’t require any discourse regarding fossils or the fossil record (which is probably the best evidence for evolution, but it’s very difficult to explain fossil evidence to someone who wants to “see” evolution if you don’t have fossils on hand!), and (d) bacteria are excellent for ‘showing’ evolution in action because they reproduce quickly, meaning that they can potentially evolve much faster than, say, a dog or a dolphin.

Learn all about natural selection at:
http://www.fromquarkstoquasars.com/understanding-evolution-what-is-natural-selection/

Image:
NASA