Natural Selection
Microevolution, not macroevolution
Natural selection occurs when individuals with certain genotypes are more likely than individuals with other genotypes to survive and reproduce, and thus to pass on their alleles to the next generation.
Natural selection is part of microevolution, it causes variety within a species. It makes certain already existing biological traits in a population either more or less common. But what it can't do is create new functional biological traits which were not already present in a population. Dogs only produce dogs, fruit flies only produce fruit flies, finches only produce finches, moths always remain moths, etcetera. For example we don't see any terrestrial animals growing fish fins, or stumps that could be the beginning of fins, despite the fact that many terrestrial animals lived in or close to water for all their existence. Nature shows a relation between fitness of individuals and their survival chances. This is nothing new, it's common knowledge. It weeds out the weaker individuals, but natural selection does not improve the fit individuals, it simply allows them to survive. Survival of the fittest, not improval of the fittest.
The reasons for rejecting Darwin's proposal were many, but first of all that many innovations cannot possibly come into existence through accumulation of many small steps, and even if they can, natural selection cannot accomplish it, because incipient and intermediate stages are not advantageous.
Roger Lewin said about natural selection that It can weed out some of the complexity and so slow down the information decay that results in speciation. It may have a stabilizing effect, but it does not promote speciation. It is not a creative force as many people have suggested. Stanley N. Salthe said that There is no strong opinion in evolutionary biology that complexity increase has evolved in living systems by way of natural selection. Jeffrey H. Schwartz said that Huxley had argued well before Mivart [that] natural selection played no role whatsoever in producing change. Fanatic evolutionist Ronald Fisher said that Natural selection is not evolution. Natural selection is a conservative or preventive mechanism at best. For a fish to grow for example fully functional lungs or wings countless intermediate mutations would be required. On top of that all intermediate mutations would have to be beneficial. Besides the fact that mutations are mainly harmful, the countless small intermediate steps neccessary to reach a new beneficial and fully functional feature are not beneficial. The beginning of little non-functional stumps before reaching a new fully functional feature would not aid the host's survival, on the contrary. On top of that an aquatic animal evolving into a terrestrial animal would need to evolve fully functional lungs alongside its gills, but nobody has ever seen these kind of transitional animals in real life or in the fossil record. Therefore it is much more logical to say that natural selection would weed those cripples out long before any beneficial stage could possibly be reached.
Artificial selection
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together.
Dogs descended from the wolf. But dogs are inferior to their original ancestor. A copy is not better than the original. Dog breeding has never led to superdogs but it has led to vulnerable dog races which suffer all kinds of typical dog diseases. Artificial breeding is a form of inbreeding and everybody knows that inbreeding is usually not very beneficial to the health and survival chances of future generations. So it rather shows degeneration instead of macroevolution. All dog races known today were possible because the genetic makeup of the wolf readily contained all the necessary specified information to make that variety possible, like size or color for example. This is called phenotypic variety. It is possible due to a life form's genotype, its already existing and unique genetic makeup. So selection does not create new features in existing life forms but it makes certain already existing features more common under for example certain environmental conditions. Dogs are of course not the only example of this. We have strong evidence from the human species as well...
Darwin & Wedgwood inbreeding
Charles Darwin's studies of heredity, adaptation and evolution included many experiments into the effects of crossbreeding and inbreeding in both plants and animals. Such consanguineous pairing often resulted in weaker, more sickly descendants. Ironically, his own lineage and marriage could have been experiments as well. At the age of 29, he proposed to his first cousin, Emma Wedgwood, the daughter of his mother's brother. Darwin realized the dangers of inbreeding and wondered if his close genetic relation to his wife had had an ill impact on his children's health, three (of 10) of whom died before the age of 11. In a letter to friend, Darwin noted his concern for his children, writing that "they are not very robust."
source screenshot
The aristocracy has a long history of inbreeding in order to keep their wealth and riches in the family. Darwin and his wealthy and powerful fellow naturalists of the Victorian era were no exception. Darwin himself once wrote: I very much fear that my eldest girl Etty will never be strong; and Lenny has been often ailing for last 2 years with intermittent (but only symptomatically so) pulse. My poor constitution like everything else is transmitted by inheritance. It is extraordinary that Darwin believed that artificial breeding could be used to somehow support his theory of macroevolution while he himself was the product of family inbreeding with of course obvious degenerative results; namely his own bad health and his weak children. Nevertheless he popularized the belief in macroevolution based on speculation against the best of observations. It is of course also extraordinary that so many people around the world have fallen for the ideas and beliefs of such a contradictory man. Historians say it was the death of his daughter Anne that radically altered Darwin's belief in Christianity and made him more willing to proclaim his theories and his religious doubts while in fact it was certain that his own inbreeding, and that of the previous generations of his family line, put his children at high risk of bad health. Darwin only had himself to blame.