Department of Biochemistry and Molecular Biology, Bldg. CIBUS-Faculty of Biology, University of Santiago de Compostela, 15782, Santiago de Compostela, Galicia, Spain.
Naturwissenschaften. 2023 Nov 2;110(6):53. doi: 10.1007/s00114-023-01882-5.
What is life? Multiple definitions have been proposed to answer this question, but unfortunately, none of them has reached the consensus of the scientific community. Here, the strategy used to define what life is was based on first establishing which characteristics are common to all living systems (organic nature, entropy-producing system, self-organizing, reworkable pre-program, capacity to interact and adapt, reproduction and evolution) and from them constructing the definition taking into account that reproduction and evolution are not essential for life. On this basis, life is defined as an interactive process occurring in entropy-producing, adaptive, and informative (organic) systems. An unforeseen consequence of the inseparable duality between the system (living being) and the process (life) is the interchangeability of the elements of the definition to obtain other equally valid alternatives. In addition, in the light of this definition, cases of temporarily lifeless living systems (viruses, dormant seeds, and ultracold cells) are analyzed, as well as the status of artificial life entities and the hypothetical nature of extraterrestrial life. All living systems are perishable because the passage of time leads to increasing entropy. Life must create order by continuously producing disorder and exporting it to the environment and so we move and stay in the phase transition between order and chaos, far from equilibrium, thanks to the input of energy from the outside. However, the passage of time eventually leads us to an end in which life disappears and entropy increases.
生命是什么？为了回答这个问题，已经提出了多种定义，但遗憾的是，没有一个得到科学界的共识。在这里，定义生命的策略是首先确定所有生命系统共有的特征（有机性质、熵产生系统、自组织、可重写的预编程、交互和适应能力、繁殖和进化），然后从这些特征出发，构建定义，同时考虑到繁殖和进化不是生命的必要条件。在此基础上，生命被定义为发生在熵产生、自适应和信息（有机）系统中的交互过程。系统（生命体）和过程（生命）之间不可分割的二元性带来了一个意想不到的后果，即定义的元素可以互换，从而得到其他同样有效的替代方案。此外，根据这个定义，我们分析了暂时没有生命的生命系统（病毒、休眠种子和超冷细胞）的情况，以及人工生命实体的状态和外星生命的假设性质。所有的生命系统都是易逝的，因为时间的流逝会导致熵的增加。生命必须通过不断地产生无序并将其输出到环境中来创造秩序，因此我们在远离平衡的有序和混沌之间的相变中移动和停留，这要归功于外部能量的输入。然而，时间的流逝最终会导致生命的终结，熵的增加。
