In the last article I considered the general context in which changes in biological organisms take place. In this article, I am going to go a step further and look more in depth at some of the specific mechanisms in play. Not only has the evolutionary model survived for the past 150 years, but also a great deal of additional data has lent increased support to the overarching concept—this data has come from the geologic column and its fossil record, from DNA analysis, and radiometric dating methods—data that supports the vast age of the earth which could allow for things like speciation and common descent. But for readers who bristle at such talk, let me hasten to add that there are many ongoing areas of research that could ultimately alter, or perhaps even negate some of the current scientific thinking. Still, enough detail is already known that it is clear the nineteenth century Adventist worldview on this subject most certainly requires modification.
Central to biological change are mutations of the genetic code having both beneficial and detrimental outcomes, with the process of natural selection refereeing. Over the course of time investigators have learned a great deal about how these processes play out. Many important studies are now occurring at the genetic level through population studies where science can observe how genes pass down through the generations, and are modified. We will look at this in more depth in a future article.
Sometimes I hear individuals admit to the changing realities that are visible at the bacterial level but who then quickly turn the discussion to microevolution. Almost everyone will admit microevolution as an undeniable reality. After all, who can refute mutating viruses and antibiotic-resistant bugs and bacteria? The data is simply overwhelming. Those who embrace microevolution often draw a line between it and macroevolution—not because of scientific data but because it supports a personal narrative. Macroevolution is more difficult to establish scientifically due to certain practical limitations I will discuss below. Most scientists view such distinctions to be without merit, with the consensus being that a series of micro-changes become macro-change over time. This is not a very remarkable idea for it stands to reason that small incremental change eventually adds up to significant change. We see this all the time in the non-biological realm in everyday life.
Furthermore, the common understanding is that all biology uses the same alphabet (so to speak), and consequently, those principles of genetics derived for one organism also have application to other organisms. It was Jacques Monod, a prominent French biologist who is quoted as saying that “anything found to be true of E. coli (bacteria) must also be true of elephants.” What he is referring to here is the existence of certain general principles that seem to apply across the spectrum of biology.
Formal scientific studies that collect and analyze empirical data have become the method by which humans have unraveled the mysteries of how biological change occurs. Gregor Mendel conducted the first of these studies with his pea experiments, observing traits that he classed as dominant and recessive. While plant genetics continues to be studied today, there are also a wide range of other biological forms being studied—all the way from bacteria, to insects, to rodents, and larger mammals including humans. In such studies it is not uncommon to use very large source populations in order to observe how random genetic processes play out over many generations. In practical terms the shorter the generational cycles the better. The ideal candidates for such studies often have generational cycles measured in hours, days, weeks or months (microorganisms, insects, rodents, etc.). These studies are often carried out on the order of hundreds or even thousands of generations.
At this point, it might be helpful to put the term “generation” into some perspective. If a human generation is defined as 20-years there have been around 100 generations of humans since the time of Christ. Thus, when I discuss studies that have looked at many hundreds or thousands of generations readers should recognize immediately that such studies provide a lot of powerful information as to how the DNA code functions in the real world. But it should also become apparent why it is so difficult to achieve meaningful human studies, for in scientific terms the human generational cycle is very long.
From these studies scientist can track the path of mutations through the layers of generations. Fortunately, most mutations are neutral; that is, copy errors exist (substitutions, insertions, deletions, etc.) but generally they do not seem to have any adverse affect. If neutral mutations were excluded and harmful-to-good ratios were developed, most of them would be categorized as mildly harmful to deleterious, with only a few being beneficial. To be sure, such assessments must have environmental context attached, for what may be harmful or beneficial in one setting may not be so in another.
Though they are rare, studies suggest that beneficial mutations can and do accrue positive benefits to a genomic population, not only single point duplications and insertions of genetic material, but also mutations of small chunks of DNA, up to and including the insertion of complete genes and genomes.
The question may come up for some readers as to how these mutations establish themselves. This is actually the second part of the biology equation and involves the term most everyone knows—natural selection. Selection can occur because of the variation within a species that confer differing genetic endowments leading to varied success in survival and reproduction. Those genes that are more successfully matched to particular environmental stresses become increasingly represented within a given population and those that are less well-matched tend to get weeded out as the grim game of survival plays out. 
Interestingly, there is evidence that the human genome may be in decline, and some creationists have attributed this to the impoverished power of natural selection. Meanwhile, the professional consensus suggests that any diminishment of the genome is mostly attributable to the results of major advances in medicine. Let’s face it, in an evolutionary sense many less-fit people, genetically speaking, are alive today that in former times would not have been. So modern medicine has in essence intervened in the selection processes of nature, making possible the survival of the genetically less fit and allowing these inferior genomes to get established and represented in the larger population. James Crow, a geneticist, speculates that this reality is likely resulting in some genome deterioration, but he does not view this prospect as a threat to the human race for in his view natural selection will ultimately have the last say. Some blame such deterioration on the inadequacy of natural selection, but if that were correct we should see evidence of a general decline in fitness over time in populations where data has been acquired over thousands of generations. As Scott Buchanan has put it, in actual fact, “the opposite is true as suggested by how hard humans must work to fend off the microbes [and insects] which afflict our crops and ourselves.”
Buchanan cites the general trend in mutation accumulation studies that show that when natural selection is not operating, the population genome deteriorates, and when natural selection is operating, the average genome of the population does not deteriorate. These findings clearly contradict the claims of those who would argue otherwise, when decades of experimental studies clearly show the exact opposite?” 
So the issue that confronts every non-scientist is the great complexity involved in deciphering the significance and weight of the data where such disputes may exist. Yet if we hope to develop a general understanding of how these processes actually work, we have no choice but to stay engaged and resist the temptation to hastily cast our anchor.
While mutations and natural selection are still considered important as mechanisms for evolution, they are no longer the only known mechanisms contributing to increasing complexity and the generation of information. Two newer candidates are emergence theory and epigenetics, and there could well be more to be discovered. Emergence theory addresses the novelty found in nature that cannot be explained by reductionism. Epigenetics is the study of heritable changes in factors that influence gene expression apart from changes in the underlying DNA sequences. In short, they are important categories that do influence the way in which a biological population becomes modified. Both mechanisms tend to undercut the probability calculations made by those opposed to evolutionary concepts.
Unfortunately, as much as the Adventist worldview may object to Darwin’s idea, the current evidence is quite compelling that organisms do change in ways that allow them to meet environmental challenges, and that mutations result in speciation. Interestingly, the general framework outlined above should not be terribly controversial to most Adventists, though perhaps some of its implications may be (e.g., macroevolution/common descent, all of which will be discussed in a later article).
Nevertheless, many are guilty of speaking of “Darwinism” or “evolution” in monolithic terms as if it was all one giant undifferentiated process. The fact is this subject involves many possible discussions, covering everything from speculation about the emergence of life from favorable primordial conditions to actual observations of biological processes. Along this continuum there are a number of possible discussions—origins, fitness, survivability, selection, mutations, emergence theory, genetics, epigenetics, and common descent. Many of these categories are quite well documented on multiple levels, while a few areas are more speculative. For sure the picture is incomplete, and this will be a point of comfort for some.
Finally, some readers likely recognize the descriptive power and authenticity of evolutionary processes yet still find themselves uncomfortable with the picture of God it portrays. I myself share those concerns, for how can we possibly reconcile the loving creator of Christianity with an order designed to weed out those who are unable to meet environmental challenges? Clearly adoption of the scientific model creates its own set of problems for Christian theology. But for now, we must simply recognize that evolution is not just some wild uncorroborated idea, but in fact substantive data has accumulated that backs it up in many particulars.
In the next article I am going to turn to one of the most important developments in biology, namely, its recent rapid shift from a qualitative to a quantitative science.
——Jan M. Long, J.D., M.H.A., works for the County of Riverside, California. Previous articles in Jan M. Long's curated series "Bringing the Real World to Genesis" can be found here.
Art: Josh Keyes, Shedding, 2009
A generation for many species is very short; making generational studies possible that span many generations more than is possible with human generational studies. Bacteria may have a generational cycle that spans only a few hours. Plants and animals may have slightly longer generational periods of days, weeks or months.
An obvious example here is the sickle cell mutation, which offers some protection against malaria, and is therefore beneficial in its recessive state in areas near the equator where malaria is more prevalent, but can have a deleterious side to it when its gene expression is dominant. It is not particularly beneficial in places where malaria is not an issue. But there are also other significant mutations that can confer a benefit when recessive in form, but have negative effects when dominant. An example would be cystic fibrosis, believed to confer some protection against cholera and typhoid. On this, see Jess Buxton & Jon Turney, The Rough Guide to Genes and Cloning (The Penguin Group, 2007), p. 96.
Often being more fit may be nothing more than coloration, giving some protection to an organism against predators.
See, for example, J.C. Sanford, Genetic Entropy & The Mystery of the Genome (FMS Publications, 2008)
James F. Crow, “The high spontaneous mutation rate: Is it a health risk?” Proc. Natl. Acad. Sci. USA Vol. 94,pp. 8380-8386, August 1997.
See generally, Scott Buchanan’s discussion regarding John Sanford’s book, Genetic Entropy (cited in note 6), found at the following link http://letterstocreationists.wordpress.com/stan-4/. This article provides a very good discussion of some of the issues involved in the evolutionary process. While Scott Buchanan is not a biologist, a prominent Adventist biologist recommended this article to me as a good summation of the weaknesses inherent in Sanford’s thesis.
See Mark Buchanan article cited in note 11.
An example here would be a discussion of origins. There are a number of ideas about how all of this might have developed, but for science there mains a lot of mystery
This is a companion discussion topic for the original entry at http://spectrummagazine.org/node/5052