Natural Selection beyond Life? A Workshop Report

Abstract

Natural selection is commonly seen not just as an explanation for adaptive evolution, but as the inevitable consequence of “heritable variation in fitness among individuals”. Although it remains embedded in biological concepts, such a formalisation makes it tempting to explore whether this precondition may be met not only in life as we know it, but also in other physical systems. This would imply that these systems are subject to natural selection and may perhaps be investigated in a biological framework, where properties are typically examined in light of their putative functions. Here we relate the major questions that were debated during a three-day workshop devoted to discussing whether natural selection may take place in non-living physical systems. We start this report with a brief overview of research fields dealing with “life-like” or “proto-biotic” systems, where mimicking evolution by natural selection in test tubes stands as a major objective. We contend the challenge may be as much conceptual as technical. Taking the problem from a physical angle, we then discuss the framework of dissipative structures. Although life is viewed in this context as a particular case within a larger ensemble of physical phenomena, this approach does not provide general principles from which natural selection can be derived. Turning back to evolutionary biology, we ask to what extent the most general formulations of the necessary conditions or signatures of natural selection may be applicable beyond biology. In our view, such a cross-disciplinary jump is impeded by reliance on individuality as a central yet implicit and loosely defined concept. Overall, these discussions thus lead us to conjecture that understanding, in physico-chemical terms, how individuality emerges and how it can be recognised, will be essential in the search for instances of evolution by natural selection outside of living systems.

Pan-Evo: The Evolution of Information, and Biology’s Part in This

“…How to apply these notions to Pan-Evo, which necessarily will contain a wide variety of types of object -molecule, individual, ecosystem, etc -plus the variants within each category, such as isomers of molecules, different species in an ecosystem, or different variants within a species? Dealing with this array of possibilities requires definition and quantification of the units (eg individual) [29,32,33]. One approach to this definition comes from assembly theory; in this theory, each object can be characterized by the assembly index, which is the minimum number of steps needed to construct the object.…”

Genome Evolution from Random Ligation of RNAs of Autocatalytic Sets

“…Vasas et al (2012) discussed this problem and found that the prerequisite for evolvability are chemical reactions networks with multiple viable cores [62]. Although it remains difficult to imagine theoretical autocatalytic sets capable of evolution by natural selection [63], it is assumed here that RNA-based autocatalytic sets have this ability.…”

Novel Apparatuses for Incorporating Natural Selection Processes into Origins-of-Life Experiments to Produce Adaptively Evolving Chemical Ecosystems

“…We argue that it is time to begin experimenting with the long-term effects of the prebiotic natural selection processes that may have aided biotic life to emerge by taming the combinatorial chemical explosion. Little research, especially experimental, has been devoted to this problem [ 13 , 18 , 19 , 20 ]. Among the challenges has been the fact that most synthetic experiments have been limited to a week or less in duration [ 21 ] so that apparatuses that can explore longer-term experiments are needed such as that described, for example, by Asche et al [ 22 ].…”