XII. Experimental Results in Evolutionary Biology

So, how does all this contrast with biological studies of evolution? Turns out Lamarck was correct, there is growing evidence that mutations are indeed adaptive – mutation rates increase when organisms are exposed to stress (heat, oxidative, starvation, etc.) and, they resist mutation when not stressed. This has been studied now in many forms of yeast, bacteria, and human cancer cells across many types of stress and under many circumstances. Moreover, there are many kinds of mutations in the genetic code ranging from small changes affecting a few nucleotides, to deletions and insertions, to gross genetic rearrangements. This paper “Mutation as a Stress Response and the Regulation of Evolvability” (2007) by R. Galhardo, P. Hastings, and S. Rosenberg sums it up:

“Our concept of a stable genome is evolving to one in which genomes are plastic and responsive to environmental changes. Growing evidence shows that a variety of environmental stresses induce genomic instability in bacteria, yeast, and human cancer cells, generating occasional fitter mutants and potentially accelerating adaptive evolution. The emerging molecular mechanisms of stress induced mutagenesis vary but share telling common components that underscore two common themes. The first is the regulation of mutagenesis in time by cellular stress responses, which promote random mutations specifically when cells are poorly adapted to their environments, i.e., when they are stressed. A second theme is the possible restriction of random mutagenesis in genomic space, achieved via coupling of mutation-generating machinery to local events such as DNA-break repair or transcription. Such localization may minimize accumulation of deleterious mutations in the genomes of rare fitter mutants, and promote local concerted evolution. Although mutagenesis induced by stresses other than direct damage to DNA was previously controversial, evidence for the existence of various stress-induced mutagenesis programs is now overwhelming and widespread. Such mechanisms probably fuel evolution of microbial pathogenesis and antibiotic-resistance, and tumor progression and chemotherapy resistance, all of which occur under stress, driven by mutations. The emerging commonalities in stress-induced-mutation mechanisms provide hope for new therapeutic interventions for all of these processes.”


“Stress-induced genomic instability has been studied in a variety of strains, organisms, stress conditions and circumstances, in various bacteria, yeast, and human cancer cells. Many kinds of genetic changes have been observed, including small (1 to few nucleotide) changes, deletions and insertions, gross chromosomal rearrangements and copy-number variations, and movement of mobile elements, all induced by stresses. Similarly, diversity is seen in the genetic and protein requirements, and other aspects of the molecular mechanisms of the stress-induced mutagenesis pathways.” – “Mutation as a Stress Response and the Regulation of Evolvability” (2007) by R. Galhardo, P. Hastings, and S. Rosenberg

What does the fossil record say about evolution? The fossil record paints a mixed picture of gradualism and saltation. The main theme of the fossil record is one of stasis – fossils exhibit basically no evolutionary change for long periods of time, millions of years in some cases. There are clear instances where the geological record is well preserved and still we see stasis, e.g. the fossil record of Lake Turkana, Kenya. Sometimes, there are gaps in the fossil record. Sometimes long periods of stasis follow abrupt periods of change in fossils – an evolutionary theory known as punctuated equilibria. Other times, the fossil record clearly shows a continuous gradual rate of evolution (e.g. the fossil record of marine plankton) – a contrasting evolutionary theory known as phyletic gradualism. This paper “Speciation and the Fossil Record” by M. Benton and P. Pearson (2001) provides an excellent summary. Neither theory, punctuated equilibria, nor phyletic gradualism seems to apply in every case.

If we allow ourselves to be open to the idea of quantum mechanics in evolution, it would seem Schrödinger was right. On the fossil record, we could see quantum evolution as compatible with both the punctuated equilibria and the phyletic gradualism theories of evolution as changes are induced by stress with quantum randomness. On the biological evidence for adaptive mutation it would seem quantum evolution nails it. We have talked about the fundamental physical character of quantum mechanics and evolution. Three aspects emerge as central to the theme: quantum entanglement via a quantum network, generalization (or adaptation) through holographic quantum computing, and complexity management via the MDL principal in DNA. These three themes are all connected as a natural result of the dynamics of quantum mechanics. Sometimes, though, it can be useful to see things through a personal, 1st person perspective. Perhaps entanglement is like “love“, connecting things to become One, generalization through holographic projection like “creativity“, and MDL complexity like “understanding“. Now suppose, if just for a moment, that these three traits: love, creativity, and understanding, that define the essence of the human experience, are not just three high-level traits selected for during “X billion years of evolution” but characterize life and the universe itself from its very beginnings.

“The Force is what gives a Jedi his power. It’s an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together.” – Ben Obi-Wan Kenobi, Star Wars

The End

Creative Commons BY-NC 4.0 Automated Copyright Information: <a rel=”license” href=”http://creativecommons.org/licenses/by-nc/4.0/”><img alt=”Creative Commons License” style=”border-width:0″ src=”https://i.creativecommons.org/l/by-nc/4.0/80×15.png” /></a><br />This work is licensed under a <a rel=”license” href=”http://creativecommons.org/licenses/by-nc/4.0/”>Creative Commons Attribution-NonCommercial 4.0 International License</a>.

Leave a Reply

Your email address will not be published. Required fields are marked *