One of the ingredients in the secret sauce of evolution is usually time --great, eon-length slabs of time. Evolutionary processes aren't generally in much of a hurry, at least when we're talking about major changes. Humans, for example, started the journey toward building our better selves on the order of millions of years ago. While it's fanciful and fun to imagine that we could watch our species sprout, say, wings on our backs over the course of a few weeks (the vagaries of automotive traffic having driven us to take to the skies one by one), it seems an unlikely prospect.
Not all hope is lost for observing evolution in action though. Evolution can prove tricky to observe in the lab, but we might have better luck there trying to catch evolution at its work. After all, evolutionary processes occur over multiple generations of a species, so you'd probably need to observe something in the bacterial realm, where "generations" whiz by really fast. One approach, for example, would be to observe mutations in a simple, short-lived species such as the dreaded E. coli bacteria. In just 20 years' time, E. coli may pass through 44,000 generations.
We also see bacterial evolution in worrisome places such as the constant race modern medicine is running just to stay ahead of antibiotic-resistant bacteria -- the new strains develop and spread fast, rendering our drugs useless or certainly less effective. The U.S. Centers for Disease Control, in fact, calls antibiotic resistance "one of the most pressing health problems," adding that "almost every type of bacteria has become stronger and less responsive to antibiotic treatment when it is really needed" [source: CDC].
Antibiotic resistance isn't just reserved for bacteria either. Some insects have evolved a resistance to pesticides, and, less microscopic than bacteria or insects, the Galapagos finches have been able to hit the hyper drive on evolution. Scientists have observed the little birds engineering evolutionary changes to the shape and size of their beaks in a matter of only a few years. They're not considered major changes, but nonetheless they are evolutionary [source: PBS].
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