Some things in nature get attributed to Darwinian evolution, but might be better seen as manifestations of design or other alternative, non-Darwinian mechanisms.
In “Predictable Bacterial Diversity,” Nature highlighted some experiments that showed bacteria converging on the same mutations when exposed to identical environmental stresses. “They found many similar and a few identical mutations that underlay the evolution of diversity in the three experiments,” the article said. “The findings suggest that this evolution is a predictable process that is driven by natural selection.” The story is based on a paper in PLoS Biology that was summarized in on Science Daily, which said, “Any evolutionary process is some combination of predictable and unpredictable processes with random mutations, but seeing the same genetic changes in different populations showed that selection can be deterministic.”
This claim, however, runs contrary to the unpredictable, contingent nature of Darwin’s theoretical mechanism. If the mutations fall within the “Edge of Evolution,” as Michael Behe described in a book of that name, then the changes could be due to chance and selection pressure in an artificially designed environment. But as Randy Guliuzza has explained, the ability to adapt would better be described as designed into the bacteria than residing in the environment. The end products of the experiments, finally, are still bacterial “strains” within the same species, raising questions why natural selection, if so inexorable a process, has left bacteria content to remain so for hundreds of millions of years.
Sometimes an observation begs the question of evolution. Why, for instance, do some birds continue their mating displays after laying of eggs? Live Science explored the conundrum:
That begged the question: Why would monogamous animals have evolved to continue these display once they’d paired up?
“It’s very obvious why you’d want a display to attract a mate, but once you’ve already secured a mate, why should you bother to keep displaying?” said study author Maria Servedio, an evolutionary biologist at the University of North Carolina, Chapel Hill.
To salvage evolutionary theory from the conundrum, they came up with a less obvious answer: it helps the birds pair-bond better for the raising of young. So it may have evolutionary benefits, despite the “very obvious” why-question.
Observation: males in many species beat females in navigational ability (Live Science). A Darwinian just-so story arises to explain this in adaptationist terms: males wander farther for hunting, so only the good navigators would survive to get home and breed. As Justin Rhodes explains in a cartoony video on PhysOrg, though, the story doesn’t wash. Males would have passed on the genes for good navigation to their daughters, not just their sons. So to explain the observation, Rhodes ended up calling the adaptation a “spandrel” of selection – i.e., a byproduct of the main selection pressure that just happened to produce navigational skill as a side effect. “Maybe we shouldn’t be too eager to accept the stories, the adaptionist stories,” he said. Even things in human behavior could be due to “alternative explanations that people haven’t considered.”
It’s nice when evolutionists themselves find faults in their own theory. Sometimes, though, they still need help from their critics.