Mutology: Part 1

The word “mūtāre” in Latin translates to English as “to change” or “to exchange.” This word appears in English in several words, such as immutable, commute, or transmutation. In biology, it appears in the word “mutation,” which refers to a nucleotide in a DNA strand being accidentally swapped out with another one. This can occur without altering the expression of the gene (a “silent mutation”), or it can drastically alter the gene and its expression. Either way, mutations alter genes.

The following article is a summary of “Genealogical vs Phylogenetic Mutation Rates: Answering a Challenge,” by Robert Carter, and of the surrounding discussion and research pertaining to it. The views expressed do not necessarily reflect those of New Creation.

When considering the total genetic material contained in an organism (known as the genome), mutations are fairly uncommon, like typos in a book. Nevertheless, new mutations occur in every generation, and some survive on to the next.* So, we are all mutants to some degree, even when our phenotypes (visible traits) do not express them. As it stands, then, life is always in a state of change (mūtāre), whether we can see it or not.

Introducing Mutology

These invisible changes can tell us a lot about life history, even though most of them have no bearing on our daily lives. They are, effectively, a record of generations past. By studying them, scientists are directly studying change, ergo “Mutology,” a word I invented for this two-part series. Through Mutology, the “study of change,” scientists have discovered some compelling evidence for a young earth.  

Genealogical vs. Phylogenetic Rates

Since mutations happen in every generation, scientists have been able to establish the idea of a “mutation rate.” This calculation is an estimate of the number of genetic mutations that occur over time. This sounds like a simple calculation to make, especially since scientists can directly observe mutations in the genetic code. But there are actually several different types of mutation rates. It is important to distinguish between them.

Genealogical Mutation Rate

The “actual” mutation rate, measured as the number of mutations over a known amount of time, is the genealogical mutation rate. The genealogical rate estimates the number of mutations occurring over time. By default, this estimation leaves out the mutations that would actually cause an organism or population to die out. This is straightforward and easy to calculate.

Phylogenetic Mutation Rate

Perhaps surprisingly, most scientists refrain from using this ratio. Instead, they rely on phylogenetics, or the study of evolutionary relationships between organisms. In evolutionary biology, the phylogenetic mutation rate uses evolutionary estimates of the time to the common ancestor of two species to calculate a mutation rate.

The phylogenetic mutation rate takes the number of mitochondrial mutations that separate two species on the evolutionary family tree. It then divides that number by the assumed amount of time since the two species diverged from an ancestor. So, while the true mutation rate is simply mutations over known time, the rate scientists often use is genetic differences between species over evolutionary time. This means that the type of mutation rates scientists continually use are based more on evolutionary assumptions rather than observational science. Of course, if evolution were true, both rates should be almost the same.

Why “almost”? I’m glad you asked.

Mutation vs. Substitution Rates

Technically, the phylogenetic rate is not equivalent to the mutation rate. Instead, it reflects a species’ substitution rate. A substitution rate measures how long it takes for a mutation to replace the original code in an entire population. Some mutations—most in fact—die out before they can take over a population. Other mutations do last, and those are the only ones calculated in the substitution rate. The phylogenetic rate, therefore, reflects the substitution rate rather than the true mutation rate, since it only accounts for mutations in entire populations. It does not account for the mutations that die out between generations.

Evolutionists consider phylogenetic rates to be a perfectly accurate reflection of the substitution rate. Under this assumption, the phylogenetic rate should be slower than the actual (genealogical) mutation rate, because many mutations are removed from the gene pool (slowing down the rate of mutations over time). The question facing evolutionists and creationists is: how significant of a difference is this?

Comparing the Models of Change

When evolutionists calculate their mutation rates, they tend to arrive at something like one mitochondrial mutation per 200 generations. If you divide the number of mitochondrial mutations separating two species, by the time since those species diverged, this is roughly what you get. You may have noticed that this substitution rate is very slow. The actual mutation rate—mutations over time—is much faster. Though evolutionists would expect the mutation rate to be somewhat faster (because it takes into account mutations that die out), the degree of difference is a problem. The genealogical mutation rate is far too fast for evolution’s timescale.

Let’s take a closer look at the degree of difference. The true mutation rate (observed mutations over time) roughly adds up to 0.5 mitochondrial mutations per generation. That is one mutation for every two generations. While these are very approximate calculations, the degree of difference is staggering (recall that the phylogenetic rate is 1/200). The (valid) evolutionary assumptions are not in the same ballpark as the actual, observable mutation rates. Meanwhile, if you take the true mutation rate and calculate backwards, the ancestor of all humans can be reasonably placed in the recent (~6000 years) past. In other words, the number of mutations in living things today are best explained using observed mutation rates over a short period of time.

There are many factors that influence and change mutation rates (such as population size), so these calculations are mere estimations. But the orders of magnitude separating phylogenetic and real mutation rates are significant. The data suggests that real-time mutation rates can fit reasonably in a young-earth timeline. Phylogenetic rates, however, are far too slow to explain the rapid genealogical rates.

Is the Mutation Rate Really a Big Problem for Evolution?

Though mutation rate estimates place Adam in the recent past, many proponents of evolution believe the discrepancy between phylogenetic and genealogical rates is irrelevant or easily solved. But several studies on evolution admit that evolution-based mutation rates are far too slow. One study from 2022 measured mutation rates by observing human pedigrees. The researchers found that the mutation rate they observed was 16 times faster than the rate they expected based on phylogenetics.¹ Another study compared mice mutation rates in the wild with those raised in a lab, found that mutation rates in both groups were 6 times faster than expected.

Why are fast mutation rates such a problem for evolution? Well, consider an article from the journal Genetics, featured in the National Journal of Medicine, which poses the question “Why are Phenotypic Mutation Rates Much Higher than Genotypic Rates?”² Not only does the Journal of Medicine acknowledge the dramatic discrepancy between genealogies and phylogenies, it also points out the problem with rates being so darn fast. If you assume the genealogical mutation rates are always the same, then deleterious (harmful) mutations will build up too quickly, and cause serious problems for the organism. If the observed mutation rates are correct, species would die off too quickly to evolve, because harmful mutations are far more common than beneficial ones. The unstated alternative is that mutations do not really transform one kind of animal into another over time. In short, if the earth is 6,000 years old, the quick mutation rate makes perfect sense.

Mutology

All of life is constantly changing. Mutations, from the Latin word for “change,” are a written record of those changes. Each one, no matter how small, is a recorded datapoint that our theories and models must explain. By studying these mistakes in the genome, scientists are literally studying change.

The evolutionary model explained these changes quite well. Its predictions were logical and honest. The scientists were following the evidence where it led. Based on evolution alone, they predicted what the mutation rates would be. Or at least, they believed they were close enough to base their research on it. But once they compared their predictions to observational science—mutations happening in real time—what they found was a process occurring much faster than their model allowed. In part 2, we will see how evolutionists explain this discrepancy and evaluate whether their explanations work.

Creationists have more work to do in Mutology. But they can be confident their results will fit a biblical timeline. Change is at the heart of the field of origins, and the change we directly observe in life is occurring fast enough to place the female ancestor of all humans (known to the scientific community as “Mitochondrial Eve”) in the recent past. This revelation should give creationists the confidence to not fear the evidence, but to look deeper and follow it where it leads. It can only lead to the same Truth we find written in God’s Word.

Notes

*Specifically, only mutations in germ cells (sperm and egg cells) are passed to the next generation. Even then, each mutation has a 50/50 chance to be inherited, since each offspring inherits 50% of its genetics from each parent.

Mutology Series

Mutology: Part 2 (Coming Soon)

Footnotes

1.  Connell, J. R., Benton, M. C., Lea, R. A., Sutherland, H. G., Chaseling, J., Haupt, L. M., … & Griffiths, L. R. (2022). Pedigree derived mutation rate across the entire mitochondrial genome of the Norfolk Island population. Scientific Reports, 12(1), 6827. ↩︎
2. Bürger, R., Willensdorfer, M., & Nowak, M. A. (2006). Why are phenotypic mutation rates much higher than genotypic mutation rates?. Genetics, 172(1), 197–206. https://doi.org/10.1534/genetics.105.046599 ↩︎