One of the things we are looking for on Mars are signs that the red planet might at some point in time have housed life. Fossils would be a telltale sign – and finding fossils would certainly be the scientific find of the century, or of all time. But how do we know that we have found a fossil? Two researchers are now suggesting that there may be a ton of different processes that could produce patterns that would look like fossils – but are the product of completely abiotic reactions, and they call them pseudo-fossils.

From a philosophical perspective this is interesting for a number of reasons.

First, it is not hard to imagine that the term pseudo-fossil will become a part of the vocabulary of creationists. Will they argue that the fossils used as evidence of evolution are just pseudo-fossils? I would guess they will at least integrate this notion into their arguments (while finding it hard to come up with abiotic processes that give us, say, dinosaur bones).

Second, there is something about the patterns being so alike here that seems to suggest a deeper insight – maybe life is premised on these patterns being common in nature in biotic as well as abiotic processes? This is a point close to that of Geoffrey West in Scale – and suggests that maybe life is more mysterious in a way than we think — at least if we frame it like this: life is not something with a unique physical pattern, but there is something else about that pattern that distinguishes it from the non-living.

Now, this second point may not be very mysterious at all – in fact, this is sort of what Schrödinger suggests in What is life – where he speaks about periodicity (metabolism) and similar processes. But there seems to be something at least intriguing about metabolism and abiotic processes producing the same patterns, doesn’t there? The counter argument would be that, no, the patterns produced by both abiotic and biotic processes are going to be limited by the laws of physics and so the set of patterns that we should expect in nature are much fewer than you may think.

The generalization of the argument also seems interesting – if there are pseudo-fossils, we should expect that there are pseudo-signs for life across the spectrum – signs and patterns produced by abiotic processes that look and feel as if they were signs of life. Is that true also for signals-based SETI? Could we get a pseudo-message from the stars?

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