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What is Evolution?

Evolution. The mere mention of the word conjures up images either of the workings of the natural world or of propagandist materialism in people’s minds. To put it into perspective, the contrast is between changes in allele frequency over time and observed speciation, and science force-fitted into personal belief systems. Alleles are alternate characters in genetic material and are integral to the process of speciation. Microevolution is the changes in allele frequency within a species, whereas speciation is macroevolution and alleles are not exchanged between populations under natural settings. The difference in allele frequency grows the further back in time the search for a common ancestor extends. The molecular clock, with its neutral proteins, is related to this process and the timing of the chimpanzee, gorilla and human split has been estimated through analysing the amino acid sequence differences of the protein albumin. The creative process of evolution is complex and installs a sense of wonder.

Mainstream evolutionary science does not pass judgement on personal religious beliefs which are outside the realm of science, despite the protests of some prominent atheists. All mainstream churches, including the Roman Catholic Church and Pope John Paul II, regard creationism as unscientific and do not view a conflict between the findings of scientists and religion. Saint Augustine, who lived before evolution became the dominant theory, also disagreed with a literal interpretation of religious texts.

How evolution is defined and recognised in the fossil and gene records is not fully understood by the general public beyond generalities. Schools need to improve the quality and quantity of their evolutionary science teachings. The public know changes occur in nature, yet this is normally where their understanding peters out. Evolution is essentially the change in gene (allele) frequency over time, which began to operate after life first began. The origin of life is the realm of the separate scientific discipline of abiogenesis. Evolutionary theories propose mechanisms to interpret these changes. As expressed eloquently by Dr. Eugenie Scott (1997: 278), head of the National Center for Science Education in America, “The problem is that ‘theory’ and ‘fact’ are used differently in science and among the public. In science, a theory is a logical construct of facts, hypotheses, and laws that explains a natural phenomenon. To the general public, however, a theory is not an explanation, but a hunch or guess. To teach evolution as a theory in this sense is to teach it as something students don’t have to take seriously.”

In “Abusing Science: The Case Against Creationism”, Kitcher (1982: 37) puts forward a wonderful definition of the scientific method: “Theories are collections of statements. The observational consequences of a theory are statements that have to be true if the statements belonging to the theory are all true. These observational consequences also have to be statements whose truth or falsity can be ascertained by direct observation. Any theory that has a false observational consequence must contain some false statement (or statements). For if all the statements in the theory were true, then, according to the standard definitions of deductive validity and observational consequence, any observational consequence would also have to be true. Hence, if a theory is found to have a false observational consequence, we must conclude that one or more statements of the theory is false.”

In other words, good scientific theories have observational predictions that would falsify all or components of a theory should they prove to be incorrect. Research papers dealing with various evolutionary theories are the result of field research by genuine scientists who possess a solid grounding in biological and social sciences. Before being published, these papers undergo peer-review. Peer-review means that a scientist’s paper, submitted to a journal, is referred to their panel of anonymous reviewers. They recommend any changes to be made to the content and comment on whether the writing contained within the paper is of acceptable scientific standard. The reviewers cannot veto publication based on whether they agree or disagree with the content of the argument(s) presented, although they can submit such recommendations in their report to the journal. However, the procedural aspects of higher scholarship, unfortunately, are not in themselves evidence that higher scholarship is free of bias. Even when opinion does not intrude outright on the reviewing process, reviewers often decide that the weight of evidence makes untenable a view that later research shows to be true, and tenure decisions and funding often flow from such judgments. What is really significant about peer review is not that it is free of bias but that it is self- correcting over time.

Scientists utilising an evolutionary framework can date when mutations occurred, track them in time, determine their selective value, study their effects on the rest of the system, understand how these changes in particular organisms stimulated changes in other organisms in the ecosystem, and conduct experiments to understand the processes and outcomes of other ecosystems. In other words, evolutionary science observes the existence of genetic mutations and natural selection in operation.

As neatly summarised by Milford Wolpoff (1999, 31-32), evolution is defined as "the genetic transformation of populations through time, created by alterations in the genetic makeup of populations from generation to generation. The consequences of this process are changes in the adaptations and diversity of populations. This mechanism of descent with modification is responsible for the pattern and variety of life on earth: a tall order for so simple a concept. The theory part of the "theory of evolution" is concerned with how these changes in genetic makeup occur and what effect they have on populations. Evolutionists have critically examined the mechanisms causing genetic change, the problem of whether these mechanisms need to be viewed at the level of the gene, the individual, or the species, the issue of whether changes are gradual or episodic, and the extent to which evolution is directional. However, these is no question about two facts:
1. The process of evolution is an actuality, a hypothesis more than 100-years old that has not been disproved. For there to be no evolution, every generation would have to be exactly the same genetically as the previous generation;
2. Evolution if the singular explanation for the history of life on our planet. It is not a hypothesis about how life came to be, but rather an explanation and description of the processes governing its changes over time."

It is no coincidence that the vast majority of people trained in biological- and geological-related sciences reject most forms of pseudoscience which traditionally attempts to paint a picture of human beings being different from all the other animals, including is nearest relations, the apes. I have yet to see any other scientifically valid explanation why primates, a group which includes humans, posses a functionless L-gulono-gamma-lactone oxidase gene for the synthesis of Vitamin C, the same as all other mammals with the exception of the hamster. This is a result of primates being descended from a common ancestral group in which such a mutation first arose, and then persisted, because of the rich vitamin C environments in which primates reside.

The genetic split between chimpanzees, gorillas and humans is comparatively minor on the evolutionary scale. There are many species of snakes that would be quite difficult to distinguish if their habitats and their skin colourings were unknown. How many modern species would biologists lump together if they simply had their skeletal remains with which to reconstruct their lives is uncertain. There is also no scientific explanation as to why a barrier should be erected against primate speciation. No competent scientific hypothesis or theory has arisen since Darwin to challenge the basis of the theory of evolution. Mendelian genetics, molecular studies, radiometric dating and anatomical analyses have all served to reinforce the foundations of evolution (Strahler 1999).

Additional evidence for common descent and speciation include the fact that all mammals, with the exception of hoofed animals, have five digits; that flowering plants are found at the top of the fossil record; that all living creatures have shared genes; that features in foetus states are later absorbed; and that certain animals and plants are limited to various parts of the world as part and parcel of speciation.

It was geology creation scientists more than 100 years before the advent of Darwin's Theory of Natural Selection who noted the occurrence of distinct fossil layers. Speciation has since been observed both in the laboratory and in the wild. The following is a report by Perlman (2001) on two such cases involving the latter:
Now three California scientists, led by David Irwin of the University of California at Bushmen Diego…say they have discovered the most compelling evidence yet to buttress the theory Darwin elaborated in his epochal volume The Origin of Species, which ignited a revolution in human thought. And another biologist, David B. Wake of UC Berkeley, has added to that evidence from his own years studying evolution in a group of colourful California salamanders. Wake’s little amphibians and Irwin’s Eurasian songbirds are known as ‘ring species’ because their forms have gradually altered as their populations have settled around a geographic ring of varied habitats and adapted over time to the demands of their different environments.
“…Irwin and his colleagues tracked a single species of the drab songbirds called greenish warblers that settled to nest and breed in forest habitats encircling Asia’s treeless Tibetan Plateau. The researchers have found an evolutionary surprise: The warbling songs of the birds differ slightly in each habitat, their body sizes vary, their wing markings change, and even their genes have diverged further and further apart. Populations of warblers, like other birds, easily mate and interbreed with neighboring groups around the ring. But when Irwin studied two separate populations of the birds that coexist in Siberia far from their original range, he found that they do not mate at all, and they differ strikingly in other characteristics. What had clearly been a single songbird species now bore all the signs of having evolved into two distinct species. To meet such extremely different environments, the birds, it seems, had indeed been ‘modified for different ends,’ as Darwin put it more than 150 years ago. Irwin’s remarkable evidence of evolution in the birds called Phylloscopus trochiloides was published in a recent issue of the journal Nature.”

Irwin took measurements, DNA samples and measured their songs. In India the female recognise the males’ songs but, in Siberia, females in the two populations no longer respond to the other’s mating calls. They are reproductively isolated. A gradual divergence in the choice of mates has led to an original single population diverging into two separate species, with differences occurring in wing colouration. The ancestral group, it is estimated, arrived in the Himalayas around 8 000 BC, from where they expanded into Siberia.

In short, evolutionary theory and practive is the bedrock of modern science. It is essential that a sound understanding of its fundamental principles is taught to school children of all ages and is known by the majority of the general public.


References

Kitcher, P. 1982. Abusing Science: The Case Against Creationism. Cambridge: The MITT Press
Perlman, D. 2001. Evolving Before Our Eyes: Songbirds and salamanders bolster Darwin’s theory that change in habitat can create 2 species from one.
Scott, E. 1997. Antievolution and creationism in the United States. Annual Review of Anthropology 26: 263-89
Strahler, A. 1999. Science and Earth History: The Evolution-Creation Controversy. New York: Prometheus Books
Wolpoff, M. 1999. Paleoanthropology. Boston: McGraw-Hill.


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