There is a tendency to consider all evidences as support for the comprehensive theory of evolution that includes both the pattern of change and the mechanism of natural selection. However, direct evidences on the macroevolutionary level—such as fossil evidence, biogreography, homology, molecular—actually are limited only to support for the theory of descent with modification. Evidences specific for the theory of natural selection being applicable on the macroevolutionary level necessarily involves extrapolation from evidences on the microevolutionary level.
Textbook authors have often confused the dialogue on evolution by treating the term as if it signified one unified whole—not only descent with modification, but also the specific Darwinian and neo-Darwinian theories regarding natural selection, gradualism, speciation, and so forth. Certain textbook authors, in particular, have exacerbated this terminological confusion by lumping "evidences of evolution" into a section placed immediately after a comprehensive presentation on Darwin's overall theory—thereby creating the misleading impression that the evidences are supporting all components of Darwin's theory, including natural selection. In reality, the confirming information is invariably limited to the phenomenon of evolution having occurred (descent from a common ancestor or change of gene frequencies in populations), or perhaps including evidence of natural selection within populations.
Challenges to theory of natural selection.
In addition to the lack of evidence for natural selection being the causal agent of change on macroevolutionary levels, as noted above, there are fundamental challenges to the theory of natural selection itself. These come from both the scientific and religious communities.
Such challenges to the theory of natural selection are not a new development. Unlike the theory of descent with modification, which was accepted by the scientific community during Darwin's time and for which substantial evidences have been marshaled, the theory of natural selection was not widely accepted until the mid-1900s and remains controversial even today.
In some cases, key arguments against natural selection being the main or sole agent of evolutionary change come from evolutionary scientists. One concern, for example, is whether the origin of new designs and evolutionary trends (macroevolution) can be explained adequately as an extrapolation of changes in gene frequencies within populations (microevolution) (Luria, Gould, and Singer 1981).
Historically, as outlined in this article, the strongest opposition to Darwinism, in the sense of being a synonym for the theory of natural selection, has come from those advocating religious viewpoints. In essence, the chance component involved in the creation of new designs, which is inherent in the theory of natural selection, runs counter to the concept of a Supreme Being who has designed and created humans and all phyla. This element of chance counters the view that the development of new evolutionary designs, including humans, was a progressive, purposeful creation by a Creator God. Rather than the end result, according to the theory of natural selection, human beings were an accident, the end of a long, chance-filled process involving adaptations to local environments. There is no higher purpose, no progressive development, just materialistic forces at work. The observed harmony in the world becomes an artifact of such adaptations of organisms to each other and to the local environment. Such views are squarely at odds with many religious interpretations.
A key point of contention between the worldview is, therefore, the issue of variability—its origin and selection. For a Darwinist, random genetic mutation provides a mechanism of introducing novel variability, and natural selection acts on the variability. For those believing in a creator God, the introduced variability is not random, but directed by the Creator, although natural selection may act on the variability, more in the manner of removing unfit organisms than in any creative role. Some role may also be accorded differential selection, such as mass extinctions. Neither of these worldviews—random variation and the purposeless, non-progressive role of natural selection, or purposeful, progressive variation—are conclusively proved or unproved by scientific methodology, and both are theoretically possible.
The history of conflict between Darwinism and religion often has been exacerbated by confusion and dogmatism on both sides. Evolutionary arguments often are set up against the straw man of a dogmatic, biblical fundamentalism in which God created each species separately and the earth is only 6,000 years old. Thus, an either-or dichotomy is created, in which one believes either in the theory of natural selection or an earth only thousands of years old. However, young-earth creationism is only a small subset of the diversity of religious belief, and theistic, teleological explanations of the origin of species may be much more sophisticated and aligned with scientific findings. On the other hand, evolutionary adherents have sometimes presented an equally dogmatic front, refusing to acknowledge well thought out challenges to the theory of natural selection, or allowing for the possibility of alternative, theistic presentations.
However, at question has always been the sufficiency of extrapolation to the macroevolutionary level. As Mayr (2001) notes, "from Darwin's day to the present, there has been a heated controversy over whether macroevolution is nothing but an unbroken continuation of microevolution, as Darwin and his followers have claimed, or rather is disconnected from microevolution."
Unification Thought and Theory of Decent with Modification.
Unification Thought does not run counter to the concept of the theory of descent with modification, for it recognizes that newer forms come on the foundation of earlier forms. That is, every entity takes time to develop, whether a human adult from a single egg, the history of life on earth, or the history of a particular lineage, such as the lineage leading to the modern horse. Thus, evidences for the theory of descent with modification are in keeping with the views of Unification Thought. Of course, this “pattern of evolution” is independent of the process, allowing for deistic creation.
Unification Thought and Theory of Natural Selection.
Unification Thought does find the theory of natural selection problematic, in the sense of natural selection being the directive or creative force of macroevolutionary changes. Essentially, this theory is tied to purposelessness, philosophical materialism, and evolution as not inherently progressive. The theory of natural selection promotes the view that a higher purpose is not required or utilized to explain the seeming harmony in the world. Unification Thought clearly rejects this view, as the entire creation is centered on purpose. Natural selection is also tied to philosophical materialism, which holds that matter is the main reality of existence and mental and spiritual phenomena, including thought, will and feeling, can be explained in terms of matter, as its by-products. This is in direct opposition to the view of Unification Thought on the separation of mind and matter, with an elevated status for mind. The view that evolution is not inherently progressive, moving from lower to higher states, and that humans do not have any special status, is in opposition to Unification Thought, which recognizes the process of creation as progressive.
Of course, natural selection is a real phenomena, albeit Unification Thought finds it most consistent with religious doctrine in its ability to strengthen and develop already existing forms, rather than the creation of major new designs and taxa. For example, Rev. Sun Myung Moon has recognized the power of natural selection within a certain limited design: "There have been sudden changes at certain times to develop to a higher stage. Darwin recognized those changes…He could not see the cause; but, he could see the evolutionary result…. Evolutionary change is possible within a certain formula or plant or animal, but there is no evolutionary development from one family to another family." In a 1976 ICUS talk, Rev. Moon notes "The theory of evolution seems to be logical, but the process of the stage-by-stage progression of things can never convincingly be explained through the theory of random mutation."