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The theory of evolution has pervaded most fields of knowledge, including science, humanities, engineering, etc. Most students are taught the theory of evolution as part of an overarching worldview that explains everything in materialistic terms from medicine to economy, from human and animal behavior to molecular biology. Therefore, it is important to know the fundamentals of this theory in order to understand how this ideology influences interpretations and development of the various fields of knowledge and research.
First, what does the term “evolution” mean? The word has two meanings that are relevant here. The term evolution can be used as change in time. Populations of organisms have changed through time through minor variations (genetic change) that happen in a short time. This type of evolution is called microevolution.
Some people use the term evolution to refer to the cause or mechanism of change. Generally, they refer to the mechanism of natural selection and this is what Darwin emphasized. It is assumed that the mutation/natural selection mechanism is capable of generating new genetic information and new organisms, although this has not been proved. This type of evolution is called macroevolution, and it implies the origination of major body plans and new groups of organisms. Most evolutionists hold that the accumulation of many small changes (microevolution) over a long time generate major changes in species (macroevolution). However, this idea is increasingly facing opposition from within the evolutionary community.
Darwin, in his book On the Origin of Species (1859), defended the idea that all organisms can be traced back to a common ancestor in the distant past. In this view, all fossil and living animals and plants descend from a common ancestor through accumulation of small changes (microevolution) over millions of years.
The Idea of Evolution Before Darwin
The idea of evolution of living beings wasn’t original to Darwin. That concept already existed amidst the ancient Greek philosophers, although they did not call it ‘evolution’. They had a philosophical notion of descent with modification. Several Greek philosophers proposed different concepts of origins, some arguing that everything originated from water or air. Another common idea was that everything descended from a central and guiding principle. Aristotle suggested a transition between the living and non-living, and speculated that in everything there was a desire to move from low to high, finally becoming divine.
During medieval times the idea of evolution was not popular. In Europe, most people held to the belief on special creation as told in the biblical book of Genesis: life was the result of divine creation. Some also believed that the different life forms have not changed since the time of creation (fixism), but that is not a concept that can be inferred from the Bible.
People also believed in some form of spontaneous generation as they saw organisms (flies, rats, beetles, worms, etc.) appear spontaneously and entirely formed from organic matter in decomposition.
The Swedish naturalist Carl Linnaeus (1707-1778), considered the father of modern taxonomy for his work in the hierarchical classification of species, claimed that the fact that organisms can be classified into natural groups indicates order in diversity, that this order reveals divine origin and purpose and that the taxonomic hierarchy indicates divine purpose. At first, he believed in the fixed nature of species, but later, based on hybridization experiments on plants, became convinced that new species could arise. However, he maintained his belief in special creation in the Garden of Eden, consistent with the Biblical doctrine, to which he was quite devoted. For Linnaeus, the new species created by hybridization of plants are part of God's plan; he never considered the idea of evolution unmediated by divine action.
In the 18th century, various thinkers began to speculate about the origin of organisms outside the biblical model of creation. The German philosopher of the Age of Enlightenment Immanuel Kant (1724-1804) developed a concept of descent that anticipated Darwinist thought. Based on similarities between organisms, Kant speculated that species could have originated from a common ancestral type and suggested that “an orangutan or chimpanzee can develop organs that are used to walking, grasping objects and speak short sentences.”
The French naturalist Jean-Baptiste Lamarck (1744-1829) believed that biological evolution proceeded according to natural law. He proposed the theory of inheritance of acquired characteristics by which biological changes acquired in life are passed onto the next generation. He believed that life originated spontaneously and that organisms increase in complexity and diversity as they adapt to the environment.
The theory of evolution arose within the natural sciences and philosophy, in part aided by new ideas and interpretations in geology, especially those by the Scottish naturalist James Hutton (1726-1797), who proposed the idea of gradualism in geological processes. According to his theory, the observed changes in the topography of the Earth may be explained by mechanisms acting gradually in the present. This was the origin of the concept of uniformitarianism, which claims that the same processes that are operating today shaped the land in the past. Hutton and others observed that geological processes are slow, therefore Earth must be very old.
Uniformitarianism smoothly moved into the minds of most naturalists in Great Britain and Western Europe in the 19th century, although some significant scholars opposed it. For example, the French naturalist George Cuvier (1769-1832) opposed the idea of evolution of Lamarck and other contemporaries and proposed the idea of multiple local disasters that have caused catastrophic extinctions with most or all the creation being exterminated, followed by restocking of life forms by a new creation after each local extinction. Fossils would match the different extinctions.
A key figure in incorporating Hutton’s uniformitarian view from geology into biology was Charles Lyell (1797-1875). Lyell surmised that the slow processes acting on the surface of the earth have not changed over millions of years—how they act and the rate at which they act.
He held the idea that the present is the key to interpret the past. These ideas were very influential for Charles Darwin as he developed his theory of natural selection to explain descent with modification. Both the current understanding of how changes occur on the surface of the Earth and Darwin’s model for changes in organisms required a long time, more than the biblical model of origins provided.
Darwin’s Theory of Evolution
Darwin was influenced by the book Essay on Population (1798) published by English cleric and scholar Thomas Malthus (1766-1834). Malthus claimed that human population shows a steady trend of increase and that the increase in population is faster than the increase in food resources. This situation leads to food shortages and to struggle for survival. When Darwin published his book On the Origin of Species by Natural Selection (1859), he adopted the principle of Malthusian overpopulation in the dynamics of animal populations. Darwin’s theory is founded on similar premises: there is a universality of reproductive sex drive in organisms and more offspring are produced than ecosystems can sustain. Therefore, there is a struggle for survival and only the fittest survive.
Darwin also drew analogies from his experiments on breeding pigeons and the artificial selection carried out by farmers on plants and animals. They would select a character that they liked and breed the animals so that the successive generations would develop those characters. In a sense, it was a way to improve the population a small change at a time. Darwin thought that change in the natural world was similar, and that small changes in the wild populations would become fixed. Accumulation of many small favorable changes would eventually produce new species.
Thus, what Darwin proposed was a concept of biological evolution based on two main ideas: 1) all organisms derive from a common ancestor (universal common descent) and 2) biological diversity is rooted in the variability of traits and natural selection resulting from the struggle for survival.
Darwin’s theory faced opposition on many fronts, not the least of them from various scientists of that time. One of the most significant critiques came from Henry Charles Fleeming Jenkin (1833-1885), a professor of Engineering at the University of Edinburgh. Jenkin identified what Darwin believed to be a potentially fatal inquiry flaw in his theory: any novelties resulting from natural variations in species would be diluted in subsequent generations. In modern words, Darwin’s theory lacked a viable understanding of genetics. Darwin didn’t know of the work of a Czech monk named Gregor Mendel, whose findings in experiments of breeding peas showed that individual characteristic could be passed down from parents to offspring. Although this flaw was significant, Darwin’s appeal to the results of artificial selection among pigeon-breeders resonated well with his readers. It took a few decades after Darwin for the theory of evolution to incorporate the findings of genetics, resulting in the so-called synthetic theory of evolution, Neo-Darwinism or the modern evolutionary synthesis in the 1920s and 1930s. It led to a revision of the original theory of Darwin, which later also added complicated mathematical models of population dynamics, and new discoveries in molecular biology. Yet the modified theory still maintained random variations (now called mutations) preserved by natural selection as the fundamental evolutionary engine. Despite the initial positive reception, the Synthetic Theory proved to have its own set of problems.
The Synthetic Theory of evolution is based on four main points, which could be considered as presuppositions of the theory:
- Heritable variation. Genetic variation occurs and species are not stable but change over time. For this point Darwin could find evidence in the fossil record. Darwin, who used the term "evolved" only once in On the Origin of Species, called this point “descent with modification.”
- Natural selection that leads to speciation. Because of scarcity of resources (food, space, etc.), there is struggle for survival in nature—more individuals are born than can survive. Only the fittest survive. The mechanism of evolutionary change is natural selection (or survival of the fittest) acting in populations. Natural selection is a slow and gradual process that occurs over successive generations. Some organisms carry genes that provide some advantage in their adaptation and survival. Thus, these organisms are better equipped and produce more offspring than others. Their lineage survives.
- Cumulative change over time, producing new types of organisms. New life forms arise from the division of a lineage into two or more lineages of Also, a lineage may slowly change over time without splitting into other lineages. Although this process is very slow and imperceptible to the human eye, it leads to increased diversity in a certain period of time. The result is “speciation”, the rise of new species by reproductive isolation. Since Darwin, two modes of speciation have been suggested: gradualism, in which evolution occurs through small successive changes over millions of years, and saltationism or punctuated equilibria, in which evolution occurs in jumps, or episodes of rapid change in short periods of time followed by long periods of little change and adaptation (stasis).
- Universal common ancestry. All organisms derive from a common ancestor. Life arose from a single-cell organism and developed and changed over many generations resulting in more and more complex forms. Darwin imagined life as a tree, with the main trunk representing the common ancestor and the branches the successive ramifications in species. This point of view is called monophyly (illustrated as a tree of life).
Evidence for Evolution in Textbooks
Textbooks present several arguments for biological evolution:
- Order and sequence of appearance of fossils in the geologic column. Fossils do not show up randomly in the fossil record in the rocks. The lower strata have only marine invertebrate animals, with terrestrial animals and plants appearing in layers above. This argument assumes a long time for the history of life on Earth and uniformitarian deposition of the sedimentary rocks that contain fossils. Thus, strata register a long time of history of life on Earth from the ‘primitive’ forms to the more advanced organisms of the present.
- Occurrence of alleged intermediate or transitional fossil forms in the fossil record. If gradual evolution occurred, the fossil record should show multiple fossils of intermediate characters. For example, if turtles are the result of gradual evolution, the rocks should contain animal fossils with a steady increase in turtle-like traits until the appearance of fully formed turtles. This postulate applies to all fossil and living animal and plant forms. In reality, this is one of the most problematic arguments of the theory of evolution, because the sedimentary rocks do not show that alleged record of intermediate forms.
- Anatomical and molecular homology. Darwin saw that the bone structures of some animals look very similar to the structures of other animals. For example, the limbs of horses, bats, whales, cats and humans are anatomically similar, though they perform different functions. From this he concluded that these animals must have evolved from a common ancestor with the simpler version of the bone structure. Therefore, the similar structure indicates origin from a common ancestor. A similar argument is presented for similarities in molecular composition, especially DNA and RNA. This argument has many flaws and falls into a fallacy of circular reasoning: similarity indicates common ancestry and common ancestry leads to similarity of traits.
- Comparative embryology. Different organisms show similar embryological development, which indicates that they derive from a common ancestor. This argument is based on flawed evidence presented in the late 19th century that has been thoroughly contested by biologists, including many embryologists.
- Neo-Darwinism claims that the geographical distribution of organisms on Earth in the present and the past follows patterns that are best explained by evolution, in combination with the movement of tectonic plates over geological time. For example, certain groups of organisms that had already evolved before the breakup of the supercontinent Pangaea (about 200 million years ago in the uniformitarian time scale) tend to be distributed worldwide. In contrast, many groups of animals and plants that evolved after the Pangea breakup tend to appear uniquely in smaller regions of Earth.
These arguments of evolution can be refuted. There are solid arguments from multiple lines of evidence that suggest that evolution as common ancestry is not true. The sciences of molecular biology, genetics, paleontology, chemistry, etc. provide evidence that show that life must have been designed by a Creator. Look for articles on these subjects on this web page and in the resources linked below.
Raul Esperante, PhD
Geoscience Research Institute
 IEP (Internet Encyclopedia of Evolution), 2010, http://www.iep.utm.edu/evolutio/