Seminar on the origins of the genetic code

Next week Jorge and I will give a seminar to report on the work we did during our 2-month stay at the Earth-Life Science Institute:

An iterated learning model of the origin of the genetic code

Tom Froese (National Autonomous University of Mexico, UNAM)
Jorge Campos (National Autonomous University of Mexico, UNAM)

Date: July 25, 2017
Time: 14:00
Room: ELSI-2 Building – ELSI Lounge
Host: Nathaniel Virgo

Theories of the origin of the genetic code take translation for granted and assign an essential role to natural selection and/or mutation of hereditable traits to explain its non-randomness and error robustness. And yet the translation system depends on high fidelity replication. Woese proposed a solution to this fundamental bootstrapping problem by arguing that optimization of the code could have preceded and facilitated evolution of the translation system, and that its evolution was accelerated by communal innovation. He conjectured that early evolution was dominated by horizontal exchange of cellular components among loosely organized protocells rather than by vertical transmission of genetic material, and that lineages of individuals did not exist until after the emergence of the last universal common ancestor. Crucial outstanding problems are clarifying the agency of selection in communal evolution, and verifying whether it provides a rational basis for codon assignments. Here we demonstrate that horizontal transfer of code fragments can in principle give rise to key properties of the genetic code. In accordance with Woese’s claim that the dynamic of communal evolution is primarily determined by the organization of the recipient cell, and taking inspiration from comparisons between the advent of the genetic code and the emergence of human language, we created an iterated learning model of a group of protocells. Previous models of the origin of the genetic code have reproduced its regularity and optimality as well as its universality, but this is the first model to reproduce these features without vertical descent. This proof of concept suggests another modality of evolution: not only was Darwinian evolution (dominated by vertical transmission of genes) arguably preceded by Lamarckian evolution (vertical transmission with heredity of acquired traits), the latter was possibly preceded by Woesian evolution (dominated by horizontal acquisition).

Black box

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Emergence in Chemical Systems

On June 23-26 the University of Alaska, Anchorage, will host the international conference Emergence in Chemical Systems 4.0. I was invited to give a talk. My title and abstract are as follows:

Motility at the origin of life and the evolution of the genome

Tom Froese

Traditionally, there has been a dispute about whether metabolism or replication came first during the origin of life. Yet both of these approaches are in implicit agreement that the first forms of life were basically passive. That shared assumption has begun to be challenged by a new generation of metabolism-first approaches, emphasizing that movement and adaptive behavior could have played an important role right from the start (1-3). I introduce this theory of a behavior-based origin of life and consider how it can help to inform our thinking about the origins of the genetic system.

References
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