The neodarwinistic (evolution) theory is just a theory, which is hard to be proven true. The majority of people believe in it, but by far not everyone and among the people who believe in it there is still disagreement concerning the way the evolution is supposed to work. In this chapter pro and contra arguments with respect to the evolution theory will be presented. In the discussion forum you can give your opinion and discuss this subject with the other users of this page.
Fossils are the petrified remains or print of organisms in rocks. Fossils show that there used to live other species than there do now. That means that species have been extinct and that others have come into existence. It appears that older fossils are less complex than younger (see also the background information about dating techniques) The complexity of organisms has grown. The neodrawinistic evolution theory gives an explanation for it.
The process, in which plants or bones turn into stone, is called fossilisation. Fossilisation appears in fairly predictable orders of events, but in each stadium information and specimens are lost. If mortal remains start to decomposition, the soft tissues generally disappear quickly through carrion eaters and bacteria.
The hard parts, such as teeth and bones, can remain undamaged, but after a while they do disintegrate when they are still in contact with air. This will not happen when the organism for example is covered by dust.
While more layers are deposits, the bones below ground level undergo changes.
| Fig 2.2.6:
The cavity in the bones can be mineralised and bone tissues can be crystallised. The bones slowly transform to stones. Rock formations can be raised or turned over and the fossilised bones can come to the surface, which is caused by erosion.
Human's caudal vertebrae
Organs can loose their function because of the adaptation of the organism to a new environment. Those organs can disappear as the species evolves. Sometimes there are there are still some remains of those former organs, the so-called rudimentary organs. Rudimentary organs come into existence the same way as the original organ but do not develop and do not have a function. An example of such an organ for mankind is the appendix. The appendix of herbivorous animals is much further stretched and has a function in the digestion. For man it does not have that function anymore. Another example concerns the caudal vertebrae. These are grown into one and do not have a function anymore. Because the human ancestors began to live differently their tail became redundant and finally disappeared. The caudal vertebrae are the remains our ancestor's tail. Rudimentary organs show that a species once looked differently and this can be explained by the evolution theory.
De embryos of a chicken and a human
There are similarities between the embryonic development of different species of animals. Especially in the earliest phases of development the embryos have many similarities. See (fig.) 3.1.2. The fact that the embryos look like each other very much makes it plausible that there is affinity and that those species have a common ancestor. According to the recapitulation hypothesis all phases of the evolution of the species of that animal are repeated during the embryonic development. However, it appears that many phases are shortened and others are changed. Human embryos develop some sort of gills in the area of the neck, which quickly develop into a part of the auditory organ among other tings.
De limbs of different animals
The organs of different organisms are often built the same way, although those organs do not always have the same function. See fig. 3.1.3. The wing of a bat serves to fly and the arm of a human serves to grab things. The primitive form of the bones is the same; they are homologous organs. Homologous organs have similarities in construction and have the same embryologic way of development. Organisms with homologous organs are likely to be related.
Finally, almost all organisms have biochemical similarities. Most chemical processes in organisms are based on the same principles and all organisms are built up from the same materials. That is not all, since big parts of the DNA and enzymes of different species of organisms correspond as well. The DNA of a chimpanzee, for example, is over 95 percent equal to human's DNA.
Some people doubt whether the neodarwinistic theory of evolution can provide an explanation beyond any doubt for the great changes in evolution. An example of such a great change is the coming into being of mammals from reptiles. Other people assume that it is possible. At present there is a lack of data for many of these kind of considerable changes. These are the so-called missing links. Further research produce more and more data, but there are still many missing links that could be used as counter arguments for evolution.
The neodarwinistic evolution theory also cannot explain why mankind has such a head start on all other animals. By far man is the most intelligent animal on earth. The smarter or stronger an animal is, the less enemies it has. If an animal barely has any enemies, the law of "survival of the fittest" is not applicable anymore and the species will not evolve as long as this head start remains.