Life and life only: a radical alternative to life definitionism
Life and life only: a radical alternative to life definitionism
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DOI：
10.1007/s11229-018-1852-2
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发表时间：
2020-07-01
期刊：
影响因子：
1.5
通讯作者：
Doolittle, W. Ford
中科院分区：
文献类型：
--
作者：
Mariscal, Carlos;Doolittle, W. Ford
迄今为止，科学界还没有明确接受生命的定义。令人沮丧的是，一些作者提倡标准定义的替代方案。其中包括使用一系列特征，关注生命的影响，或对生物圈而不是生命本身进行分类；将生命视为一个模糊类别、一个过程或一组偶然属性；或者提倡“观望”，直到创造或发现其他生命实例。但这些持怀疑态度、可操作性和多元化的方法非但没有解决问题，反而加剧了争论。鉴于这些方法都失败了，我们提倡采取新的策略。在本文中，我们扭转了通常的推理思路，认为“生命问题”源于对生命本质的错误思考。科学家们通常将生命概念化为一个类别或种类，并将地球生命视为它的一个实例。相反，我们主张将地球生命（大写“L”）视为一个个体，就像现在认为的物种一样。按照这种观点，生命是一个单系进化枝，起源于最后一个普遍的共同祖先，并包括其所有后代。我们可以继续实用地使用“生命”（小写“l”）这一类别来指代各种现象与生命之间的相似之处。但相关的相似之处只是兴趣和偏好的问题，而不是事实的问题。那么，在宇宙中寻找其他生命只是在天体生物学家认为最有吸引力的任何意义上（例如新陈代谢、进化、信息等）寻找与生命部分相似的实体。这并不意味着在宇宙其他地方寻找进化的复杂性或在实验室中创造它是徒劳的，但关于它们是否算作“生命”的争论却是徒劳的。讽刺的是，最终放弃“生命”这个概念可能会让我们对进化复杂性的探索更加富有成果。我们解释原因。
To date, no definition of life has been unequivocally accepted by the scientific community. In frustration, some authors advocate alternatives to standard definitions. These include using a list of characteristic features, focusing on life's effects, or categorizing biospheres rather than life itself; treating life as a fuzzy category, a process or a cluster of contingent properties; or advocating a 'wait-and-see' approach until other examples of life are created or discovered. But these skeptical, operational, and pluralistic approaches have intensified the debate, rather than settled it. Given the failure of even these approaches, we advocate a new strategy. In this paper, we reverse the usual line of reasoning and argue that the "life problem" arises from thinking incorrectly about the nature of life. Scientists most often conceptualize life as a class or kind, with earthly life as a single instance of it. Instead, we advocate thinking about Earth's Life (with a capital 'L') as an individual, in the way that species are now thought to be. In this view, Life is a monophyletic clade that originated with a last universal common ancestor, and includes all its descendants. We can continue to use the category 'life' (lower case 'l') pragmatically to refer to similarities between various phenomena and Life. But the relevant similarities are a matter of interest and preference, not a matter of fact. The search for other life in the Universe, then, is merely a search for entities that resemble parts of Life in whatever sense astrobiologists find most appealing (e.g. metabolism, evolution, information, etc.). This does not mean that the search for evolved complexity elsewhere in the universe or its creation in the lab are futile endeavors, but that debates over whether they count as 'life' are. Ironically, finally abandoning the concept 'life' may make our searches for evolved complexity more fruitful. We explain why.