Three implications of biological evolution
Ever since Charles Darwin published his book "Origin of Species," biological evolution has become the hottest spot in biology and even in the whole scientific community. The idea of biological evolution not only brings the controversy in biology, it also touches on religious, social, ethical, legal, and even influenced the two world wars.
The term biological evolution in different minds of people may have different meanings, which can be broadly classified into three categories:
First: The earliest life found in the earth existed 3.5 billion years ago, there are millions forms of comtemporary life that did not exist then. New species arrives, old species extinct. A reasonable scientific explanation is that every form of life may have its biological ancestor, newer creatures were derived from their ancestors. This is the first implication or type of evolution, also known as macro-evolution. The evidences could be from fossils, comparative embryology, comparative anatomy studies.
Second: the composition of each type of organism is not immutable, each creature has own characteristics, such as color, height or running at different speeds. Some of the features enable them to enjoy more survival advantages than their peers in the same species. For example, if a new color in moths provides the moths better disguise, the moths with that color would easily escape predators and live longer, resulting in more offsprings. After some time moths with this color will have increased proportion in the population. However, no matter how high the ratio, moths with the color would be the same species as ones with unchanged color, they still can mate among them with healthy offspring. This is the second type of biological evolution, also known as micro-evolution. The evidence is primarily from biogeography, molecular biology. This is a scientific fact with little controversy, even among the most conservative religious groups.
Third: the emergence of a new species (macro evolution) is the result of the micro-evolution, "micro-evolution of species occurs all the time, change may lead to the formation of species, which is the origin of new species." This means generation of the new species by Darwin's theory of natural selection, it is the crown or core of the Darwin's theory . This is the third type of the evolution. It is the topic of process and mechanism of biological evolution. Other popular mechanisms of the evolution have proposed, including use and disuse, geographic isolation, neutral theory, and so on.
According to Darwinian biologists, the emergence of a new species takes at least thousand and thousand years (1). But if it were true, people should have little chance to see the emergence of new species for obvious reasons, as ones can live less than a hundred years, and cannot see a whole process that takes thousands and thousands years.
However, large number of new species are discovered within a short period of time, they are just one generation process. For example, numerous animals and plants are generated by processes of polyploids and parthenogenetic reproduction which occur in the absence of natural selection(2); in less than 20 years, two different species of cichild fish has evolved from one type of cichild fish (3); over tens of thousands of new species are discovered every year. The most important battlefield on the Internet for Darwinian evolutionist is talk.origin, it lists several pages of new-found species, none of them is clearly and unequivocal case to support them through natural selection; the vast majority of polyploid (4); contradictory to prediction by the Darwin's theory.
To avoid this embarrassment, neo-Darwinian changed their argument. They claim natural selection the primary mechanism for generating new specis, those not by natural selection are only a few exceptions, such an interpretation would make the neo-Darwin's theory a sheer pseudo-science (5).
If a theory is a scientific one, it must have characteristics to be proved wrong at certain circumstances. We can check these three types of evoltuion to see if they are falsifiable.
The first type of evolution is falsifiable. If human fossils were found in earth layer over 50 millions years ago, then macro-evolution can be proved to be wrong. This situation has not occurred so the type of evolution is correct.
The second one is also falsifiable. After migration people have certain characteristics as the result of adaptation to environmental changes. For example, person's skin color in the higher latitudes has become lighter to absorb more ultraviolet light. If human skin color remains same with changes in the environment, micro-evolution were proved to be wrong.
The third one is not falsifiable. The way to disprove it is: If you can observe generation of any new species not by micro-evolution, this type of evolution would be proved wrong. Or if we observed that most new species arise not by micro-evolution, this type of evolution can be proved wrong. However, ones only observe arrival of new species in one-generation process without involvement of natural selection. Nobody knows for sure if mutation and natural selection could generate any new species or no new species at all, it is impossible for anybody to see the whole process, it is a mission impossible.
Darwin is not the first one to propose a biological evolution. Europeans in the late 17 century had broad discussions of biological evolution. Darwin's grandfather and Lamarck published own books to propose their ideas regarding evolution. Darwin's main contribution is to propose natural selection as the mechanism for arrival of a new species. Without it, Darwin's contribution to the evolutionary theory will be greatly discounted.
Darwinians and religous conservatives often argue existence of certain transitional fossils. To them proof of transitional fossils would validate Darwin's theory of natural selection. This is actually a misunderstanding.
Ones look for the existence of transitional fossils, simply ones suspect there may be something missing with known chain of evolution. Between organism A and B, the two known species，there might be one or several unknown creatures between them. Discovery of Archeopteryx, the transitional animal between birds and reptiles species, does not tell us how it was generated. Animals generated through polyploidy and parthenogenesis leave us their own fossils, those fossils are transitional ones.
One of the most important and basic principle in scientific debate is to be sure what we are debating. When we debate the theory of the evolution, we must know if we are debating the first type of the biological evolution; or the second, or the third one? Since the first and second types of evolution are widely accepted by scientific community, or even by many religious groups, there is little left to debate. Anti-evolutionists often say that evolution is merely a hypothesis or a theory, not a scientific fact. In many cases they do not deny the first and second types of the evolution, they argue against validy of the third one.
Scientific American is the most popular scientific magazine, also a staunch supporter of the neo-Darwinian theory, it says:
“Darwin proposed the theory of evolution through natural selection, when the scientists engaged in a fierce debate this, but to rely on paleontology, genetics, zoology, molecular biology and other disciplines in the mass of evidence against the theory of evolution of other blame, and gradually established. Today, the theory of evolution has been victorious in all areas, of course, except the field of public awareness (5).” The statement only tells: even predominated by neo-Darwinism in the scientific community, the American public does not accept the idea, and refuses the brainwashing.
(1) Why Evolution Is True. Jerry A. Coyne 2009, the Peenguine Group