The grayness of the origin of life — 2021 — Life
Read the full text here: https://doi.org/10.3390/life11060498
In the search for life beyond Earth, distinguishing the living from the non-living is paramount. However, this distinction is often elusive, as the origin of life is likely a stepwise evolutionary process, not a singular event. Regardless of the favored origin of life model, an inherent “grayness” blurs the theorized threshold defining life. Here, we explore the ambiguities between the biotic and the abiotic at the origin of life. The role of grayness extends into later transitions as well. By recognizing the limitations posed by grayness, life detection researchers will be better able to develop methods sensitive to prebiotic chemical systems and life with alternative biochemistries.
Citation: Smith HH, AS Hyde, DN Simkus, E Libby, SE Maurer, HV Graham, CP Kempes, B Sherwood Lollar, L Chou, AD Ellington, GM Fricke, PR Girguis, NM Grefenstette, CI Pozarycki, CH House, and SS Johnson, 2021. The grayness of the origin of life. Life 11(6):498. https://doi.org/10.3390/life11060498
Image description: Figure 1 from the paper cited above, whose caption reads: "Illustration of the three macromolecules used by life on Earth, as both constituent parts (a,c,e) and larger-scale structures (b,d,f), which fulfill the roles described in the chemoton model: metabolism, compartmentalization, and information storage. (a) A polypeptide consisting of eight amino acids. (b) Spinach ferredoxin protein structure, PDB 1A70, showing alpha-helices, beta-pleated sheets and loops structures . (c) A phospholipid containing fatty acid tails made of repeating 2C units. (d) A segment of a phospholipid bilayer, which forms cell membranes. (e) A short chain of DNA, illustrating the Watson–Crick nitrogenous bases. (f) An A-form double helix showing the structure of DNA storage."