This morning the following image of a creationist came to mind: He/she stands atop a massive pile of sand, shovel in hand. At their feet, at the head of the shovel, is a divot just removed. The creationist claims, See, it’s not a pile, it’s a hole!
More sand has just been dumped atop the ever-growing pile of evidence for evolution.
In Evolution More Rapid Than Darwin Thought I encountered this finding:
Magnus Karlsson discovered that the distribution between the color variants of pygmy grasshoppers differs across different environments. In recently burnt over areas, a very high proportion of the grasshoppers are black. In unburnt areas, on the other hand, the black variant is unusual. What’s more, the proportion of black grasshoppers changes very rapidly between generations in the burnt areas, whereas the proportion in unburnt areas remains the same over the same period of time.
Magnus Karlsson presents data that show that the pygmy grasshoppers’ color changes by natural selection. He believes that the primary cause of these changes is birds and other animals that hunt using their vision. The black grasshoppers are simply less visible against the burnt background, so they survive more often. But as the environment changes and becomes more complex, the advantage of being dark diminishes, and other color variants can once again increase in number. [bold mine]
One of my first thoughts was, “but can we be sure this isn’t an epigenetic, phenomenon–that something in the environment isn’t triggering genetic expression in the grasshopper?” Fortunately, the research looked into that and ruled it out. This finding is all about the speed of natural selection. And it can be quite fast indeed.
First posted at 360 Degree Skeptic.