Darwinists Revise Selectionism Again

A key belief of evolution refuted:
recessive gene mutations are
not hidden from selection

by Jerry Bergman, PhD

How evolution is supposed to work

According to standard neo-Darwinian theory, the main source of new genetic variety that results in evolution is genetic mutations. This genetic variety, in turn, is said to be acted on by natural selection, gradually producing new organisms. As the theory goes, less-fit organisms are, in time, eliminated from the gene pool, and more-fit organisms are allowed to survive. These more genetically fit organisms are, therefore, more likely to pass on their genes to the next generation. Gradually, the more-fit organisms will become numerically dominant. For this reason, without genetic variety, evolution cannot occur.

Consequently, “Mutation or incorrect copying”[1] is central to evolution because “no mutations, no evolution.”[2] In addition, many mutations are neutral, meaning they do not affect the phenotype. The fact is, “If all mutations were neutral, natural selection could not occur.”[3]

But mutational load kills

The problem for evolution is that as the mutation load increases, it will eventually cause genetic catastrophe and, in the long run, extinction of the animal type. Not all genes are vulnerable to this process, though. Dominant genes express their trait  even if only a single copy is present. Conversely, it was once thought that “recessive mutations remain hidden from selection while heterozygous.”[4] The reason is, recessive genes require two copies (i.e., the alleles must be homozygous) in order for their trait to be expressed in the phenotype.

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According to theory, a dominant allele will mask the effect of a recessive allele when both are present in the genome, causing the dominant phenotype to be expressed in the phenotype. As explained by Professor Christian Gilissen of Radboud University Medical Center, a child receives genes from both father and mother. When a single mutation in the child leads to a disability, this must be, it was assumed, caused by a mutation in the dominant gene. A single mutation in a recessive gene should have no effect on the child. (If  observations were to show that one of the two copies is expressed in the phenotype, that would mean recessive genes too could be subject to Darwinian selection.[5])

For this reason, a genetic benefit or disorder was thought to be expressed only if the mutation occurs in both copies of a recessive gene. Consequently, recessive genes should not be subject to Darwinian selection. The reason is, in brief, “A single mutation in a recessive gene typically has no observable effect on the phenotype because the dominant allele, which is also present in a heterozygous individual, masks the recessive allele’s effect.”[6]

This conventional wisdom has been challenged

On 15 May 2025, Radboud University in the Netherlands announced results of a study that challenges this view. Gilissen and colleagues reported in a press release,

Having a single mutation in a recessive gene, in principle, has no effect on the carrier. A handicap only arises if the mutation is in both copies of the recessive gene. In our clinic we found very few of these double mutations in recessive genes in children with intellectual disabilities. Strange, because there are more recessive than dominant genes for this. So we wondered: where did all those recessive mutations go?”[7]

To find out, the researchers at Radboud analyzed the data of over 300,000 people in the UK Biobank, finding that each person carries an average of two mutations in any one of the 1,900 recessive genes. According to our current understanding of genetics, carriers of these recessive genes should not suffer from the disease. In contrast to what was expected, they have more medical problems and slightly fewer offspring than children who had two non-mutated genes.

The only conclusion from this finding was that the assumption that a “single mutation in a recessive gene has no effect on the child” was wrong.[8] If a single mutation in a recessive gene has an adverse effect on the child, this also means that humans are more prone to genetic catastrophe. The Radboud press release states:

It is a biological fact that about one hundred spontaneous mutations occur in the hereditary material of each child. [These mutations]… therefore do not originate from the parents. On average, only one of these one hundred mutations affects a gene. And only a fraction of those affects one of the hundreds of genes that can cause intellectual disability. But rare events still happen. Most intellectual disabilities arise in this way.[9]

Summary

It was long believed that dominant genes could express their trait even when only a single copy exists. In contrast, recessive genes were long believed to require two unmutated copies for their trait to be expressed in the phenotype. Thus, in contrast, dominant genes should not express the trait they control when only one copy has a mutation, while recessive genes were thought to require mutations in both copies for their trait to be expressed in the phenotype. However, the finding of the new research reviewed in this paper shows that even when only one copy of a recessive gene is damaged, it can still in some cases adversely affect the phenotype.

This is one more example of the fact that, as our knowledge of the genome increases, the complexity of the entire system also increases. In short, this finding is so significant that one reviewer said it may be “time to rewrite the textbooks.”[10] Indeed, it is past time to do so.

References

[1] Evans, Dylan, and Howard Selina, Introducing Evolution,  Icon Books, England, UK, p.55, 2001.

[2] Evans and Selina, 2001, p.56.

[3] Evans and Selina, 2001, p.57.

[4] Furney, Simon, et al., “Differences in the evolutionary history of disease genes affected by dominant or recessive mutations,” BMC Genomics 7(165):1-11, https://link.springer.com/article/10.1186/1471-2164-7-165, 2006.

[5] Radboud University Medical Center, “Recessive genes are subject to Darwinian selection,” also published by Science Daily, www.sciencedaily.com/releases/2025/05/250515132046.htm, 15 May 2025.

[6] University of Utah, “What are dominant and recessive?,” Genetic Science Learning Center, https://learn.genetics.utah.edu/content/basics/patterns/, 2025.

[7] Radboud University Medical Center, 2025.

[8] Radboud University, Medical Center, 2025.

[9] Radboud University Medical Center, 2025.

[10] Radboud University Medical Center, 2025.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,900 publications in 14 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,800 college libraries in 27 countries. So far over 80,000 copies of the 60 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.