The primary reason so many Americans reject the theory and fact of evolution is religion. I think that’s pretty undisputed. However, there is a lot of incorrect information out there promulgated by journalists who get in way over their heads, and that is also a contributing factor. For the most recent example, let’s turn to the obituary of Lynn Margulis:
The [endosymbiotic] hypothesis was a direct challenge to the prevailing neo-Darwinist belief that the primary evolutionary mechanism was random mutation.
Rather, Dr. Margulis argued that a more important mechanism was symbiosis; that is, evolution is a function of organisms that are mutually beneficial growing together to become one and reproducing. The theory undermined significant precepts of the study of evolution, underscoring the idea that evolution began at the level of micro-organisms long before it would be visible at the level of species.
This is just awful. Just awful.
Margulis’ theory showed that some organelles – primarily mitochondria and chloroplasts – were once bacteria before being taken up into eukaryotic cells. This did not overturn any major precepts, nor did it shake the biological world. It was a big idea, one that turned out to be correct, and it marked a major turning point in our understanding. But that turning point was more complementary than it was subtracting. That is, it added a good deal of knowledge, it explained some mysteries, and it opened up a lot of avenues of research (as correct ideas often do) while fitting into the broad model of evolution, but it did not diminish the importance of random mutation, natural selection, genetic drift, or any other aspect of the theory.
Moreover, Margulis’ theory did not show that “evolution is a function of organisms that are mutually beneficial growing together to become one and reproducing”. It showed that sometimes endosymbiosis happens. And when it does, it sometimes has huge contingent importance. For instance, without the mitochondria in our cells, the history of life on Earth is not even remotely the same. But there are other hugely important events which, while ultimately reliant upon historic events like moments of endosymbiosis, can be explained without the need to appeal to Margulis’ theory. For example, the rise of mammals. Of course we are eukaryotes and so we depend upon the endosymbiosis event that happened billions of years ago, but that would be like appealing to the formation of Earth to describe the construction of a skyscraper. It just isn’t necessary and, besides, planetary accretion doesn’t happen every time a worker pours some concrete.
Stuff like this is why I say science is so undermined by so many science journalists.