RE: The Biggest Misunderstandings About Evolution
To say species don't change into other species over time simply isn't scientifically correct; we have pysical evidence of this, we have SEEN new species evolve. Sure, a dog won't just evolve into a whale, but they came from a common distant ancestor. A horse won't become a giraffe but they came from a common ancestor. And we didn't evolve from today's monkeys, but we share a common ancestor.
You are right about the fruit flies, they are popular for genetics experiments due to their short lifespan. But to become something other than a fruit fly would still take a huge amount of time. What these researchers are witnessing are tiny changes in the fly population; examples of microevolution. They are witnessing evolution, but on such a small scale that the species does not drastically change. As a whole, the fruit flies will not change during this short period, but if you kept watching for millions of years, they would become something new. For a species to "evolve" it doesn't have to drastically change.
A very interesting and widely known example of an evolutionary process is provided by the population changes of light and dark colored moths during England's industrial revolution. Basically, there was this peppered moth species who existed in light and dark colored variants (an example of polymorphism). Before the industrial revolution, most of the population of these moths was light colored, with the dark colored variant almost unseen. But with the industrial air pollution darkening the ecosystem, this trend progressively inverted, with dark colored moths ending up largely outnumbering the light colored ones. A change in the ecosystem changed the relative fitness of both variants, with natural selection promoting the survival of the now fittest dark colored variant.
You can read more about this here: https://en.wikipedia.org/wiki/Peppered_moth_evolution .