Identifying molecules as biosignatures with assembly theory and mass spectrometry - 2021 - Nature Communications
Read the press release here: https://www.gla.ac.uk/news/headline_793740_en.html
Read the full text here: https://doi.org/10.1038/s41467-021-23258-x
The search for alien life is hard because we do not know what signatures are unique to life. We show why complex molecules found in high abundance are universal biosignatures and demonstrate the first intrinsic experimentally tractable measure of molecular complexity, called the molecular assembly index (MA). To do this we calculate the complexity of several million molecules and validate that their complexity can be experimentally determined by mass spectrometry. This approach allows us to identify molecular biosignatures from a set of diverse samples from around the world, outer space, and the laboratory, demonstrating it is possible to build a life detection experiment based on MA that could be deployed to extraterrestrial locations, and used as a complexity scale to quantify constraints needed to direct prebiotically plausible processes in the laboratory. Such an approach is vital for finding life elsewhere in the universe or creating de-novo life in the lab.
Citation: Marshall, SM, C Mathis, E Carrick, G Keenan, GJT Cooper, H Graham, M Craven, PS Gromski, DG Moore, SI Walker, and L Cronin. Identifying molecules as biosignatures with assembly theory and mass spectrometry. Nature Commununications 12, 3033 (2021). https://doi.org/10.1038/s41467-021-23258-x
Image Description: Figure 1 from the paper cited above, showing the assembly pathways of an object made of red/blue blocks, a word, and a molecule as stepwise additions of new units or repeated blocks. The figure also shows a model of pathway assembly as a random walk along a weighted tree and a chart showing the probability of the most likely path through the tree as a function of the path length.