Maher K A, Stevenson D J
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA.
Nature. 1988 Feb 18;331(6157):612-4. doi: 10.1038/331612a0.
One possible definition for the origin of life on Earth is the time at which the interval between devastating environmental insults by impact exceeded the timescale for establishing self-replicating proto-organisms. A quantitative relationship for the Hadean (pre-3,800 Myr ago) and Early Archean (3,800 to 3,400 Myr) impact flux can be derived from the lunar and terrestrial impact records. Also, the effects of impact-related processes on the various environments proposed for abiogenesis (the development of life through chemical evolution from inorganic materials) can be estimated. Using a range of plausible values for the timescale for abiogenesis, the interval in time when life might first have bootstrapped itself into existence can be found for each environment. We find that if the deep marine hydrothermal setting provided a suitable site, abiogenesis could have happened as early as 4,000 to 4,200 Myr ago, whereas at the surface of the Earth abiogenesis could have occurred between 3,700 and 4,000 Myr.
地球上生命起源的一种可能定义是，因撞击导致的毁灭性环境冲击之间的间隔时间超过建立自我复制原生物体所需时间尺度的那个时刻。冥古宙（38亿年前之前）和太古宙早期（38亿年至34亿年）撞击通量的定量关系可以从月球和地球的撞击记录中推导出来。此外，还可以估算与撞击相关的过程对为无生源说（通过无机材料的化学演化产生生命）所提出的各种环境的影响。利用一系列关于无生源说时间尺度的合理值，就可以为每种环境找到生命可能首次自行出现的时间间隔。我们发现，如果深海热液环境提供了一个合适的场所，无生源说可能早在40亿至42亿年前就已发生，而在地球表面，无生源说可能发生在37亿至40亿年之间。
