The ability to self-sustain is one of the essential properties of life. However, a consistent and satisfying definition of self-sustainability is still missing. Currently, self-sustainability refers to either “no-intervention by a higher entity” or “regeneration of all the system’s components”. How to connect self-sustainability with heredity, another essential of life, is another problem, as they are often considered to be independent of each other. Last but not least, current definitions of self-sustainability failed to provide a practical method to empirically discern whether a chemical system is self-sustaining or not. Here I propose a definition of self-sustainability. It takes into account the chemical reaction network itself and the external environment which is simplified as a continuous-flow stirred tank reactor. One distinct property of self-sustaining systems is that the system can only proceed if molecular triggers (or called, seeds) are present initially. The molecular triggers are able to establish the whole system, indicating that they carry the preliminary heredity of the system. Consequently, life and a large group of fires (and other dissipative systems) can be distinguished. Besides, the general properties and various real-life examples of self-sustaining systems discussed here together indicate that self-sustaining systems are not uncommon. The definition I proposed here naturally connects self-sustainability with heredity. As this definition involves the continuous-flow stirred tank reactor, it gives a simple way to empirically test whether a system is self-sustaining or not. Moreover, the general properties and various real-life examples of self-sustaining systems discussed here provide practical guidance on how to construct and detect such systems in real biology and chemistry. This article was reviewed by Wentao Ma and David Baum.

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自持化学反应系统的定义及其在遗传中的作用

自我维持的能力是生命的基本属性之一。然而，仍然缺乏对自我可持续性的一致和令人满意的定义。目前，自我维持是指“上级实体不干预”或“系统所有组件的再生”。如何将自我维持与遗传（生命的另一个基本要素）联系起来是另一个问题，因为它们通常被认为是相互独立的。最后但并非最不重要的是，当前对自我维持的定义未能提供一种实用的方法来凭经验辨别化学系统是否自我维持。在这里，我提出了自我可持续性的定义。它考虑了化学反应网络本身和外部环境，简化为连续流动搅拌釜反应器。自我维持系统的一个独特属性是，该系统只有在最初存在分子触发器（或称为种子）时才能继续运行。分子触发器能够建立整个系统，表明它们携带了系统的初步遗传。因此，可以区分生命和一大群火灾（和其他耗散系统）。此外，这里讨论的自我维持系统的一般属性和各种现实生活中的例子表明，自我维持系统并不少见。我在这里提出的定义很自然地将自我可持续性与遗传联系起来。由于此定义涉及连续流动搅拌釜反应器，因此它提供了一种简单的方法来凭经验测试系统是否自持。而且，此处讨论的自我维持系统的一般特性和各种实际示例为如何在真实生物学和化学中构建和检测此类系统提供了实用指导。本文由马文涛和大卫鲍姆审阅。