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Since Charles Darwin suggested that it was necessary to look at "the facts and arguments" on both sides of the issue to reach a satisfactory conclusion, he would surely not object to us closely scrutinising the ideas he put forward in The Origin of Species. |
If we do this, we shall observe that Darwin was right about some things, and very wrong about others. Despite its title, Darwin's Origin actually says very little about the origin of species. It is mainly about natural selection and the variation which has allowed different species to adapt to changing conditions. |
ARTIFICIAL SELECTION Charles Darwin bred domestic pigeons, and was amazed at the many different variation that could be obtained by selecting certain traits. He wrote: "I am fully convinced that all are descended from the rock-pigeon." (chapter 1). Today, there are even more varieties of pigeons and doves: some have fan-shaped tails, some have feathers on their feet, some have crests on their head. Pigeon breeders develop new varieties by selecting interesting characteristics to breed from. But why did Darwin |
DARWIN in the DOCK |
Pigeons will always be pigeons! Darwin also knew how farm animals had been improved by artificial selection. Cattle can be bred either to produce high milk yields, and also to produce beef, but they are still cattle. NATURAL SELECTION Darwin reasoned that if human breeders could get such big changes in a short time, natural selection could, over a much longer period, produce new species and even different kinds of animals. He wrote, “How fleeting are the wishes and efforts of man! How short his time! And consequently how poor will be his results, compared with those accumulated by Nature during whole geological periods!” Darwin was wrong for three reasons. Firstly, in artificial selection, changes are for the benefit of the breeders. It doesn’t benefit a cow to produce lots of extra milk, since in nature she only needed enough for her calf. Natural selection only works for the good of the species. Secondly, there is a limit to the amount of variation possible, whether by artificial or natural selection. It would not be possible to breed a cow that produced 1000 gallons of milk a day. Thirdly, natural selection can only select what is already there; it cannot add new genetic information. Reptiles could not evolve into birds, and bears could not |
Cattle can be bred for high milk yields (above), or to produce beef (below) |
Darwin realised that his theory rested upon the assumption that no living organisms had appeared abuptly. He wrote, “If numerous species belonging to the same genera or families have really started into life at once, the fact would be fatal to the theory of evolution through natural selection.” Unfortunately for Darwin (and his modern-day followers) thatis exactly what we do find. In some of the lowest |
sedimentary rocks on earth — the Cambrian — we find the fossils of a vast array of complex creatures. These are mainly invertebrates, but there are also true fish (vertebrates). This has been dubbed "The Cambrian Explosion." The late Professor Stephen Jay Gould wrote, "In a geological moment near the beginning of the Cambrian nearly all modenr phyla make their appearance." Professor Richard Dawkins admits that "they look as though they were just planted there without any evolutionary history”. There is no evidence that these complex animals had ancestors, which, using his own criterion, should be enough to kill Darwin's theory. |
The "Cambrian explosion": a reconstruction of some of the animals which appear abruptly as fossils in the Cambrian rocks. |
think this kind of variation was evidence for evolution? All pigeons and doves belong to the same "kind", and the genetic information to produce these differences must have been present in their original ancestors. So although Darwin was right to suggest that all these different pigeions had descended from rock doves (wild pigeons).he was quite wrong to present this as evidence that all life on earth had evolved from some hypothetical "common ancestor" that lived millions of years ago. |
evolve into whales — even though Darwin wrote that he had "no great difficulty" in imagining this could have happened. Such changes would need new organs and structures, and the genetic information to produce them would not be available for selection.When he visited the Galapagos Islands, Darwin noted variations between the tortoises which inhabited different islands. He also noticed similar variations between the islands' finches. ABRUPT APPEARANCE: |
A Galapagos tortoise |