7.19.1 Common descent
In the world of real science, common descent of animals is completely noncontroversial; any controversy resides in the microbial world. There, researchers argued over a variety of topics, starting with the very beginning, namely the relationship among the three main branches of life.
A group of organisms is said to have common descent if they have a common ancestor. In modern biology, it is generally accepted that all living organisms on Earth are descended from a common ancestor, or ancestral gene pool.
Charles Darwin proposed a theory of universal common descent via an evolutionary process. This theory is now generally accepted by biologists, and the “last universal common ancestor” (LUCA or LUA), that is, the most recent common ancestor of all currently living organisms, is believed to have appeared about 3.9 billion years ago. The theory of a common ancestor between all organisms is one of the principles of evolution, although for single cell organisms and viruses, single phylogeny is disputed. With a few exceptions, the vast majority of Creationists reject this theory. Evidence of common descent includes evidence from fossil records, comparative anatomy, and geographical distribution of species, comparative physiology and comparative biochemistry.
7.19.2 Darwin on the eye
It is better to quote Darwin on this subject:
“To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection seems, I freely confess, absurd in the highest possible degree.
Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to light hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound.”
Anti-evolutionists continually cite this passage as supposed evidence that Darwin himself threw in the towel when faced with truly difficult and inherently implausible cases. But if they would only read the very next sentence[s], they would grasp Darwin’s real reason for speaking of absurdity ‘in the highest possible degree. Darwin set up the overt ‘absurdity’ to display the power of natural selection in resolving even the most difficult cases. The very next line, gave three reasons, all supported by copious evidence, for resolving the absurdity and accepting evolutionary development as the cause of optimally complex structures.
7.19.3 Another Darwin’s misquote
Both Ben Stein, in the movie “Expelled: No Intelligence Allowed”, and William Jennings Bryan, in the 1925 Scopes Trial, used the same quote mining of a passage from Charles Darwin‘s book “The Descent of Man”. The heavily edited quote gives the impression that Darwin is supporting eugenics, when he is in fact explicitly rejecting it.