Abstract: (public access)One thing that discriminates living things from inanimate matter is their ability to generate similarly complex or non-random structures in a large abundance. From DNA sequences to folded protein structures, living cells, microbial communities and multicellular structures, the material configurations in biology can easily be distinguished from nonliving material assemblies. Many complex artefacts, from ordinary bioproducts to human tools, though they are not living things, are ultimately produced by biological processes—whether those processes occur at the scale of cells or societies, they are the consequences of living systems. While these objects are not living, they cannot randomly form, as they are the product of a biological organism and hence are either technological or cultural biosignatures. A generalized approach that aims to evaluate complex objects as possible biosignatures could be useful to explore the cosmos for new life forms. However, it is not obvious how it might be possible to create such a self-contained approach. This would require us to prove rigorously that a given artefact is too complex to have formed by chance. In this paper, we present a new type of complexity measure, which we call ‘Pathway Complexity’, that allows us not only to threshold the abiotic–biotic divide, but also to demonstrate a probabilistic approach based on object abundance and complexity which can be used to unambiguously assign complex objects as biosignatures. We hope that this approach will not only open up the search for biosignatures beyond the Earth, but also allow us to explore the Earth for new types of biology, and to determine when a complex chemical system discovered in the laboratory could be considered alive.
This article is part of the themed issue ‘Re-conceptualizing the origins of life’ – Marshall SM, Murray ARG, Cronin L. 2017 A probabilistic framework for identifying biosignatures using Pathway Complexity.Phil. Trans. R. Soc. A 375: 20160342. http://dx.doi.org/10.1098/rsta.2016.0342More.
It sounds as though these people are looking for answers, not just reasons to circumvent or shut down a discussion.
A friend explains that they are attempting to quantify thresholds for distinguishing between organized/complex objects and those that could simply occur under abiotic (unguided) processes.
It might be a way of getting a handle on irreducible complexity, suggests another, because it takes the order of arrangements into account.
See also: Pearlside eyes unexpectedly at odds with other deep-sea fishes’: Chance, fate, or design? Are we allowed to wonder?
Trigger warning: Science Mag: Scallop’s eye “Fine-tuned for image formation” Thought: The way things are going, the war on reason and common sense required to protect Darwinian naturalism will run into problems with the English language, and any other language that is needed to convey meaning. Could researchers buy the right to use conventional meaningful terms now and then without Darwin’s Dobermans let loose on them? Maybe they could apologize in advance and pay a fee… with a special fine levied if the paper is cited anywhere?
A biologist awakens from reductionism and begins to rediscover life