Mutational Bias Challenges NeoDarwinian Random Mutations

When I was pursuing my degree in biology in the late seventies on the way to my medical degree, Neo-Darwinian "random mutations” were felt to be a "fact like gravity.” It seems things have changed, though not for gravity.

Two new studies show mutations are not random as per NeoDarwinism challenging 100 years of evolutionary dogma. 


The first study is named, "Mutation bias reflects natural selection in Arabidopsis thaliana" by Monroe et al. (2022). It challenges the prevailing axiom that mutations occur randomly with respect to their consequences. The authors found that mutations occur less often in functionally constrained regions of the genome, such as gene bodies and essential genes. This suggests that mutation bias is not random.

The findings of this study overturn the axiom of random mutations in two ways. First, they show that mutations are not evenly distributed throughout the genome, but are instead concentrated in certain regions. Second, they show that mutation bias is not simply a byproduct of natural selection, but is also an active force that helps to shape the evolution of genomes.

The study by Monroe et al. has important implications for our understanding of evolution. It suggests that mutation bias is a powerful force that can help to shape the evolution of genomes. This is because mutation bias can help to reduce the accumulation of deleterious mutations, which can lead to the evolution of new and beneficial traits.

The findings of this study also have implications for our understanding of human evolution. It is possible that mutation bias has played a role in the evolution of human traits, such as our large brains and our capacity for language. This is an area of active research, and it is likely that we will learn more about the role of mutation bias in human evolution in the years to come.

Here are some of the key takeaways from the study:

  • Mutations do not occur randomly with respect to their consequences.

  • Mutation bias can help to reduce the accumulation of deleterious mutations.

  • Mutation bias may have played a role in the evolution of human traits.

Here are some key quotes from the article:

  • Since the first half of the twentieth century, evolutionary theory has been dominated by the idea that mutations occur randomly with respect to their consequences. 

  • In contrast to expectations, we find that ...mutation bias is the primary force behind patterns of sequence evolution around genes.

  • We conclude that {epigenetic}-associated ‘mutation bias’ reduces the occurrence of deleterious mutations ...challenging the prevailing paradigm that mutation is a directionless force in evolution.”

  • Our discovery yields a new account of the forces driving patterns of natural variation {i.e. natural cellular mechanisms}, challenging a long-standing paradigm regarding the randomness of mutation and inspiring future directions for theoretical and practical research on mutation in biology and evolution.

This study is a significant contribution to our understanding of evolution, and it has the potential to change the way we think about the role of mutations in evolution.

The second study is named, "De novo mutation rates at the single-mutation resolution in a human HBB gene region associated with adaptation and genetic disease." 

It  found evidence that mutations may not be as random as previously thought. The study, led by researchers from the University of Haifa in Israel, found that the rate of generation of the HbS mutation, which protects against malaria, is higher in people from Africa, where malaria is endemic, than in people from Europe, where it is not.

This finding challenges the core assumption of neo-Darwinism, which states that mutations are random events that occur with equal probability in all genes. The researchers suggest that the HbS mutation may be generated preferentially in the gene and in the population where it is of adaptive significance.

This study is the first to provide evidence of nonrandom mutation in human genes. It has the potential to fundamentally change our understanding of evolution and the role of mutations in the process.

The study's findings have been met with mixed reactions from the scientific community. Some scientists have hailed the study as a major breakthrough, while others have been more cautious in their assessment.

Here are some of the key takeaways from the study:

  • Mutations are not be as random as previously thought.

  • The rate of generation of certain mutations may be influenced by environmental factors.

  • This finding has the potential to fundamentally change our understanding of evolution.

The study's findings are still being debated by scientists, but they have the potential to have a major impact on our understanding of evolution. It will be interesting to see how the research community responds to these findings in the coming years.

Endnotes

  1. Monroe, J.G., Srikant, T., Carbonell-Bejerano, P. et al. Mutation bias reflects natural selection in Arabidopsis thaliana. Nature 602, 101–105 (2022). https://doi.org/10.1038/s41586-021-04269-6 

  2. Daniel Melamed, Yuval Nov ,Assaf Malik, et al. De novo mutation rates at the single-mutation resolution in a human HBB gene region associated with adaptation and genetic disease. Genome Res. ,January 14, 2022, doi:10.1101/gr.276103.121 





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