The video below, narrated by Jon Perry, answers the question, What Exactly Is Evolution. It starts with an excellent definition of evolution that closely resembles my own preferred, minimal, defintion of evolution at What Is Evolution?. Here's the definition in the video ...
(Evolution is defined as) any change in the heritable traits within a population across generations.The first example involves a new mutation that arises in an amoeba-like organism. Because this new mutation in inherited by a daughter cell, the video declares that "evolution has officially occurred."
What this means is that mutation becomes a mechanism of evolution. I prefer to think of evolution as "heritable changes in a population spread over many generations" in order to make it clear that change in a single generation doesn't qualify. I also prefer to think of mutation as a mechanism for generating variation and not a mechanism for causing evolution but this can be legitimately debated.
The second example is two badgers mating to produce an offspring that has a different combination of characteristics than either parent. According to the video "evolution ... has officially occurred." This is incorrect. Populations evolve, not individuals. It's quite possible for the individuals in a given generation to have different combinations of traits than either of their parents while the frequency of alleles in the population remains unchanged. Thus, evolution has NOT occurred.
The idea that it's populations that evolve and not individuals is crucial to a correct understanding of evolution and it's a shame that the video promotes a common misconception.
Bug_girl at Skepchick liked this video and so did PZ Myers at Pharyngula.
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