The Modern Scientific Theory of Evolution
The modern theory of evolution began to develop in the 18th century through the work of Linnaeus (1707-78), Buffon (1707-88), Erasmus Darwin (1731-1802), Lamarck (1744-1829), and in the 19th century in the works of Charles Darwin (1809-82) and his followers. 'On the Origin of Species’ written by Charles Darwin (1859) gave details and demonstrations of his scientific theory of evolution, according to which, life on the earth evolved by a gradual and yet continuous process from the earliest forms of living organisms to the latest product, man. Natural selection, variation and heredity are said to be the factors through the operations of which new species arise out of existing ones. When new characters are produced by the variability of organisms, natural selection decides their survival or death. If the characters do not adapt to their environment, they are eliminated in the competition. If, on the other hand, they equip themselves better for the struggle, they tend to survive. The offsprings of the successful tend to resemble the parents in exhibiting the favoured variation to a greater degree than the parents, and a new type becomes established by a continuous piling up of small useful accretions through many generations.
The two original components of Darwin's theory were (i) that evolution is gradual, and (ii) that the nature of the change is dictated by natural, not divine, selection. Both of these are closely interlinked, and both are at the heart of controversy today, as they were in Darwin's time.4
Many naturalists 5 accepted Darwin's gradualism because it accorded well with what they saw in living species. But critics could not accept that all the world's marvellous species and their extraordinary structures, such as those of the eye, could have arisen only by chance. Some biologists accepted that minor changes might be the result of natural selection, but held that beyond extremes within a range of variation, a new species could not arise by natural selection alone. The only way in which the boundaries of species might be breached, they contended, would be through a sudden jump.
Paleontologists 6 who dug up and classified the remains of extinct species raised another major objection to gradualism. They argued that if Darwin was right, they should be able to find a series of specimens that could be laid out in a gradual continuum from one major type of animal to another. If, for example, reptiles evolved into mammals, there should be fossils representing every gradation between these two groups. Instead, the paleontologists found more gaps than continua. Darwin conceded this, but he thought that further researches would reveal the intermediate links. As it turned out, only a few links have been found, and this issue is a part of today's controversy.7
There are biologists today who maintain that the
evolutionary process jumps from one species to another. Their theory is called 'saltationism' (from Latin saltáre to leap). The early geneticists maintained that plants and animals sometimes produce offsprings with unusual abnormalities or variations that could be considered well outside the normal range of variation. These odd offsprings were called sports. Hugo de Vries, an early Dutch geneticist, also observed that the sports undergo some kind of permanent, large-scale alteration of the hereditary units. He called the change a mutation. On the other hand, gradual changes or variations were called by him fluctuations.
In the early twentieth century, evolutionists were divided into two camps. There were geneticists, who saw only evidence for sudden discontinuous change or mutation. They supported the saltationist view. On the other hand, there were naturalists who supported Darwinian gradualism. By the 1930s, however, the rift between these two camps came to be healed by a new evolutionary theory that Julian Huxley named the 'modern synthesis'. As part of the new theory, Dobzhansky emphasized the need for what he called isolating mechanisms. He recognized that a new species could not emerge from an old one in the wild, if its early members continue to breed with the parent stock. The novel features would either be swamped by the parent stock, or they would be spread throughout the existing species, causing the entire species to evolve slightly. If part of the species population is to split from the parent stock, it must be isolated from the larger population of stock. A river, mountain range, or some other geographic feature must prevent the small variant group from breeding with its original stock. Eventually, the isolated population would become so different that biological differences would
prevent inbreeding. In 1972, Stephen Jay Gould and Niles Eldredge asserted that evolutionists had become too rigid in insisting of gradualism. They put forth a new theory that reduced gradualism to a rare event and named the dominant phenomenon 'Punctuated Equilibriums'. According to them, species are, for most of their existence, in evolutionary equilibrium or stasis. They change very little, if at all. But once in a while the stasis is punctuated by a sudden 'speciation event'; somehow, a small population of the parent species begins evolving rapidly and, within a relatively few generations, becomes a distinct species.8
There has been a debate between the scientific theory of evolution and the special creation theory. This debate is most acute in the United States, where Christians faithful to the creation account in the Book of Genesis have seized upon "intelligent design" (I.D.) to show that the blanks in the evolutionary narrative are meaningful. (Vide an account of a debate between Richard Dawkins, who holds the view that on the basis of the physical evidence that we possess today of the universe, evolution should lead towards atheism, and Francis Collins, who holds the view that material science not only points to Immanent God but also to Transcendental God, who exists outside of space and time, — the account was reported in Time, January 15, 2007). We may also refer to Roger Sperry, who made the following important statement in 1995:
"With a scientist's faith in empirically verified truth and a long commitment to research in the brain, behavioral and
life sciences, I spent most of my working years accepting the scientific account of the nature and origins of life and the universe. If science said that human life is lacking in any ultimate purpose, value, or higher meaning — that we and our world are driven merely by mindless, indifferent physical forces — I was prepared to face this. Like many scientists, I preferred to seek out and confront the truth, however harsh, rather than live by false premises and illusory values. The more I learn about the workings of the brain and how it processes information, the stronger becomes my allegiance to the type of truth that receives consistent empirical validation in the outside world.
"Nevertheless, without abandoning or compromising scientific principles, I have come around almost full circle today to reject the type of truth science traditionally has stood for, along with its dominant central tenet that everything in our universe, including our human psyche, can be accounted for in terms entirely physical — that science has absolutely no need for recourse to conscious mental or spiritual forces. As a brain scientist, I have come to believe in the reality and power of conscious mental/cognitive entities of the mind or spirit and the indispensability of their causal control for both brain function and its evolution — and that science has been wrong all along with categorical denial of this."
We may also refer to Sherwin Nuland, a clinical professor of surgery at Yale University who, in an interview on his book published in 1997 'The Wisdom of the Body’, stated as follows:
"I think there is an evolutionary accomplishment of the human cortex, the cortex of the brain, and the way it relates to the lower centers of the brain and the way it relates to the
entire body, the way it accepts and synthesizes the information, uses information from the environment, from the deepest recesses of the body, the way it recognizes dangers to its continued integrity. And I think this is precisely what the human spirit is doing. The human spirit is maintaining equilibrium, and it largely is related to its normal physical and chemical functioning....
"Here are these seventy five trillion cells, and every cell has hundreds of thousands of protein molecules in it and they are constantly interacting with one another in what would appear to be chaos. And in fact, if you were to be able to lower yourself into a cell, you would be terrified because it would seem so chaotic. If it had sound, you couldn't live with it, it would be so noisy. And yet what is actually occurring is that these reactions are all counteracting threats to the survival of that cell. And I think that there is within the human organism, only the human organism because of our cortex and our ability to process information, I think that there is an awareness of the closeness of chaos.
"And I think there is a lot of evidence for that including cultural evidence....."9.
It can be said that, as the field of research is expanding, both microcosmically and macrocosmically, fresh data are pouring upon us to suggest that the materialistic view of the universe and the materialistic interpretation of evolution should lose force and give way to a new way of looking at the universe and evolution where consciousness may come to be regarded as more primary and fundamentally determinative power.