The presence of most of the atoms involved in the building up of living cells can be explained by their intrinsic physico-chemical properties. Yet, the involvement of the alkali metal potassium cation (K+) is somewhat of a mystery for most scenarios of origins of life, as this element is less abundant than its sodium counterpart in sea water, the original medium bathing the majority of proposed sites as the cradle of life. Potassium is involved in key processes that could as well have been fulfilled by sodium (such as maintenance of an electrochemical potential or homeostatic osmolarity). However, K+ is also required for the setup of a functional translation machinery, as well as for a fairly enigmatic metabolic pathway involving the usually toxic metabolite methylglyoxal. Here we discuss the possibility that potassium has been selected because of some of its idiosyncratic properties or whether it is just the outcome of the accidental place where life was born. Specific physico-chemical properties of the K+ ion would argue in favour of positive selection in the course of life's evolution. By contrast, the latter explanation would require that life originated on potassium-rich environments, possibly continental but yet of unknown location, making K+ presence just a frozen accident of evolution.

中文翻译：

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为什么自然选择钾。

活细胞积累中涉及的大多数原子的存在可以通过其固有的物理化学性质来解释。但是，对于大多数生命起源场景而言，碱金属钾阳离子（K +）的参与在某种程度上还是个谜，因为该元素的含量不及其钠元素在海水中的含量高，而原始介质中大部分元素被认为是生命的摇篮。钾也可以通过钠来完成的关键过程（例如保持电化学势或体内渗透压）。但是，对于功能翻译机器的设置以及涉及通常有毒代谢物甲基乙二醛的相当神秘的代谢途径，也需要K +。在这里，我们讨论了由于钾的某些特质特性而选择钾的可能性，或者它是否仅仅是生命出生的偶然地方的结果。K +离子的特定理化性质将主张在生命进化过程中积极选择。相比之下，后一种解释将要求生命起源于钾含量丰富的环境，可能是大陆环境，但位置未知，这使得钾离子的存在只是冰冻的进化事故。