Hazen Robert M, Wong Michael L
Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, DC 20015, USA.
NASA Hubble Fellowship Program, Space Telescope Science Institute, Baltimore, MD 21218, USA.
PNAS Nexus. 2024 Jun 25;3(7):pgae248. doi: 10.1093/pnasnexus/pgae248. eCollection 2024 Jul.
To what extent are naturally evolving systems limited in their potential diversity (i.e. "bounded") versus unrestricted ("open-ended")? Minerals provide a quantitative model evolving system, with well-documented increases in mineral diversity through multiple stages of planetary evolution over billions of years. A recent framework that unifies behaviors of both biotic and abiotic evolving systems posits that all such systems are characterized by combinatorial richness subject to selection. In the case of minerals, combinatorial richness derives from the possible combinations of chemical elements coupled with permutations of their formulas' coefficients. Observed mineral species, which are selected for persistence through deep time, represent a miniscule fraction of all possible element configurations. Furthermore, this model predicts that as planetary systems evolve, stable minerals become an ever-smaller fraction of the "possibility space." A postulate is that "functional information," defined as the negative log of that fraction, must increase as a system evolves. We have tested this hypothesis for minerals by estimating the fraction of all possible chemical formulas observed from one stage of mineral evolution to the next, based on numbers of different essential elements and the maximum chemical formula complexity at each of nine chronological stages of mineral evolution. We find a monotonic increase in mineral functional information through these nine stages-a result consistent with the hypothesis. Furthermore, analysis of the chemical formulas of minerals demonstrates that the modern Earth may be approaching the maximum limit of functional information for natural mineral systems-a result demonstrating that mineral evolution is not open-ended.
自然演化系统在其潜在多样性方面（即“有界”）与不受限制（“开放式”）的程度如何？矿物质提供了一个定量的演化系统模型，在数十亿年的行星演化的多个阶段中，矿物质多样性的增加有充分的文献记载。最近一个统一生物和非生物演化系统行为的框架假定，所有这些系统的特征都是受选择影响的组合丰富性。就矿物质而言，组合丰富性源于化学元素的可能组合及其化学式系数的排列。经过漫长时间筛选而留存下来的已观察到的矿物种类，只占所有可能元素构型的极小一部分。此外，该模型预测，随着行星系统的演化，稳定矿物在“可能性空间”中所占的比例会越来越小。一个假设是，“功能信息”（定义为该比例的负对数）必然会随着系统的演化而增加。我们通过估计在矿物演化的九个时间阶段中，从一个阶段到下一个阶段观察到的所有可能化学式的比例，来检验关于矿物质的这一假设，该估计基于不同必需元素的数量以及每个阶段的最大化学式复杂性。我们发现，在这九个阶段中矿物功能信息呈单调增加——这一结果与该假设一致。此外，对矿物化学式的分析表明，现代地球可能正在接近天然矿物系统功能信息的最大极限——这一结果表明矿物演化并非是开放式的。
