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What are we looking for when we look for the earliest life?


Image result for origin of life NASA Here’s a new word: dubiofossil

From Sophia Rootsh at Aeon:

Schopf’s Apex chert fossils stood in as exemplars of every dubiofossil collected by a geobiologist seeking life in the Archean Era. As Henry Gee later put it in the pages of Nature: ‘It is hard to tell the difference between a bacterium – especially a fossil bacterium – and a bubble.’ Richard Kerr posed a similar question in Science: are these the ‘earliest signs of life [or] just oddly shaped crud?’ Brasier diagnosed the problem as one of deduction: for many geobiologists studying early life, ‘If it looks like a cyanobacterium … then the most parsimonious explanation is that it is a cyanobacterium.’ Yet morphological similitude – or comparison of ancient to extant life – was no longer enough; ‘lifelike’ dubiofossils were more often than not inorganic patterns.

The question of what life is or is not, what it does or does not look like, or how or when it did or did not arise (or how often it has arisen) are questions that researchers always pose within the context of ongoing theories and commitments – to natural selection, to palaeontological conjecture, to whether life is understood as substance, process or self-assembly. When we ask where life came from and what it looks like, we are asking which qualities define the contours of life – pattern or structure, simplicity or complexity, form or information, metabolism or reproduction. This means that life is a concept – it bears meaning and the force of signification; it carries historical baggage, philosophical expectations and scientific framings. Life is something about which people – life scientists and others – must be persuaded. But of course, to say that life is up for debate certainly does not damn the scientists who seek it and sometimes stumble upon its wily facsimiles. On the contrary, it means that our theories of life are spectacularly lively. More.

The researchers are not going to be further ahead, of course, if they adopt PoMo terminology (“historical baggage, philosophical expectations and scientific framings”), which are a way of giving oneself permission to ignore data.

See also: Diversity of complex viruses messes up origins theories


What we know and don’t know about the origin of life

One simple and measurable dividing line between life and nonlife is patterned movement of electric charges. Neural actions, digestion, communication, all involve identifiable movements of ions. Bacteria are especially good at communication through ions. Has anyone tried to spot the remnants of persistent patterned charge fields in rocks, especially rocks containing semiconductor materials?polistra
March 17, 2018
12:01 PM

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