An international and interdisciplinary team working at the Earth-Life Science Institute (ELSI) at the Tokyo Institute of Technology has modeled the evolution of one of biology’s most fundamental sets of building blocks and found that it may have special properties that helped bootstrap itself into its modern form. …
All life, from bacteria to blue whales to human beings, uses an almost universal set of 20 coded amino acids (CAAs) to construct proteins. This set was likely “canonicalized” or standardized during early evolution; before this, smaller amino acid sets were gradually expanded as organisms developed new synthetic proofreading and coding abilities. The new study, led by Melissa Ilardo, now at the University of Utah, explored how this set evolution might have occurred.
There are millions of possible types of amino acids that could be found on Earth or elsewhere in the Universe, each with its own distinctive chemical properties. Indeed, scientists have found these unique chemical properties are what give biological proteins, the large molecules that do much of life’s catalysis, their own unique capabilities. The team had previously measured how the CAA set compares to random sets of amino acids and found that only about 1 in a billion random sets had chemical properties as unusually distributed as those of the CAAs. …
They found that even hypothetical sets containing only one or a few modern CAAs were especially adaptive. It was difficult to find sets even among a multitude of alternatives that have the unique chemical properties of the modern CAA set. These results suggest that each time a modern CAA was discovered and embedded in biology’s toolkit during evolution, it provided an adaptive value unusual among a huge number of alternatives, and each selective step may have helped bootstrap the developing set to include still more CAAs, ultimately leading to the modern set.
If true, the researchers speculate, it might mean that even given a large variety of starting points for developing coded amino acid sets, biology might end up converging on a similar set. As this model was based on the invariant physical and chemical properties of the amino acids themselves, this could mean that even Life beyond Earth might be very similar to modern Earth life. Co-author Rudrarup Bose, now of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, further hypothesizes that “Life may not be just a set of accidental events. Rather, there may be some universal laws governing the evolution of life.” Paper. (open access) – Melissa Ilardo, Rudrarup Bose, Markus Meringer, Bakhtiyor Rasulev, Natalie Grefenstette, James Stephenson, Stephen Freeland, Richard J. Gillams, Christopher J. Butch, H. James Cleaves. Adaptive Properties of the Genetically Encoded Amino Acid Alphabet Are Inherited from Its Subsets. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-47574-x More.
It’s worth noting that the origin of the term “bootstrap”:
a loop of leather or cloth sewn at the top rear, or sometimes on each side, of a boot to facilitate pulling it on.
pull (oneself) up by (one’s) bootstraps, to help oneself without the aid of others; use one’s resources:
I admire him for pulling himself up by his own bootstraps.
It’s not clear that this can really be done, using only naturalistic resources.
It sounds as though these researchers want to quietly abandon Darwinian randomness in favor of a structuralist approach to the unfolding of life but — understandably — do not want to hear from an army of angry Darwinian orcs.
See also: Do genes that jump shake the tree of life? Yes. But what hope is there that textbooks could start teaching reality when even the right to question the Darwinian filler is still a big controversy in many places? Could science writers like Jabr and others agree that it is time to make textbooks about evolution sound like the reality and not like the 1925 Monkey Trial revisited?