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Top Scientific Problems with Evolution: Mutation

Photo: A fruit fly, by Macroscopic Solutions, via Flickr.

Editor’s note: We are delighted to present a series by biologist Jonathan Wells on the top scientific problems with evolution. This is the sixth entry in the series, excerpted from the new book The Comprehensive Guide to Science and Faith: Exploring the Ultimate Questions About Life and the CosmosFind the full series so far here.

Darwin insisted that new variations — the raw materials for natural selection — originated without purpose or direction, but he did not know their source. It wasn’t until 1953, when James Watson and Francis Crick discovered the molecular structure of DNA, that many biologists thought the source had been found.

Watson and Crick inferred that DNA consists of two complementary strands, each composed of a string of four subunits. In 1958, Crick proposed that the sequences of subunits specify sequences of RNA molecules that function as intermediates in the synthesis of proteins. The RNA sequences then specify the sequences of amino acids, the subunits of proteins.1

The Central Dogma

Some modern biologists think that the sequence of amino acids specifies the final form of a protein, and that proteins specify the final form of an organism. This line of reasoning is sometimes called the central dogma of molecular biology, and it can be crudely summarized as “DNA makes RNA makes protein makes us.” In 1970, molecular biologist François Jacob wrote that an organism is the realization of a “genetic program” written in its DNA.2 Under this view, changes (mutations) in DNA sequences would change the genetic program and thus modify the organism in any number of ways. Molecular biologist Jacques Monod (who shared a 1965 Nobel Prize with Jacob) wrote that with this realization, “and the understanding of the random physical basis of mutation that molecular biology has also provided, the mechanism of Darwinism is at last securely founded. And man has to understand that he is a mere accident.”3

But can DNA mutations really be the source of the variations needed for macroevolution? Certainly they can cause changes in an organism, but biologists have long recognized that most DNA mutations are either neutral (that is, they produce no observable changes) or harmful. To lead to the sort of evolution that could produce plants and animals from lower forms of life, we need mutations that cause beneficial variations. Otherwise, natural selection would either ignore them or tend to eliminate them.

Only Small Biochemical Changes

Rare beneficial mutations have been found, but all of them produce only small biochemical changes — not new organs or body plans. Frequently these advantageous changes involve the loss or diminishment of function at the biochemical level.4 Many biologists have concluded that the idea of a genetic program was wrong, and that DNA does not control the development of an organism. DNA is necessary, but not sufficient; other factors are also involved. One of these is spatial information in membrane patterns.5 According to evolutionary biologist Thomas Cavalier-Smith, the idea that DNA contains all the information needed to make an organism “is simply false.” Membrane patterns play 

a key role in the mechanisms that convert the linear information of DNA into the three-dimensional shapes of single cells and multicellular organisms. Animal development creates a complex three-dimensional multicellular organism not by starting from the linear information in DNA…but always starting from an already highly complex three-dimensional unicellular organism, the fertilized egg.6

Since the 1970s, molecular biologists have performed comprehensive screens for mutations affecting embryo development in fruit flies, roundworms, zebrafish, and mice. Hundreds of mutations have been identified, but none of them change development in the fundamental ways needed for macroevolution. All the available evidence leads to the conclusion that no matter how much we mutate a fruit fly embryo, only three outcomes are possible: a normal fruit fly, a defective fruit fly, or a dead fruit fly. Not even a house fly, much less a roundworm, a zebrafish, or a mouse, can be produced via mutations.

Tomorrow, speciation.


  1. Francis H.C. Crick, “On protein synthesis,” Symposia of the Society for Experimental Biology 12 (1958), 138-163. 
  2. François Jacob, The Logic of Life, trans. Betty E. Spillmann (Princeton, NJ: Princeton University Press, 1973), 3.
  3. Jacques Monod, quoted in Horace Freeland Judson, The Eighth Day of Creation (New York: Simon & Schuster, 1979), 217.
  4. Michael Behe, Darwin Devolves: The New Science About DNA That Challenges Evolution (New York: Free Press, 2019). 
  5. Jonathan Wells, “Membrane Patterns Carry Ontogenetic Information That Is Specified Independently of DNA,” BIO-Complexity 2014 (2); Jonathan Wells, “Why DNA Mutations Cannot Accomplish What Neo-Darwinism Requires,” Theistic Evolution: A Scientific, Philosophical, and Theological Critique, eds. J.P. Moreland, Stephen C. Meyer, Christopher Shaw, Ann K. Gauger, and Wayne Grudem (Wheaton, IL: Crossway, 2017), 237-256.
  6. Thomas Cavalier-Smith, “The membranome and membrane heredity in development and evolution,” Organelles, Genomes and Eukaryote Phylogeny, eds. Robert P. Hirt and David S. Horner (Boca Raton, FL: CRC Press, 2004), 335–351.