最近在富含碳的近地小行星 Ryugu 上发现核苷酸，这些样本是由 JAXA 的 Hayabusa2 太空船于 2020 年送回地球，促使科学家重新思考地球生命的起源。发表于 Nature Astronomy 的一项研究证实，Ryugu 样本中存在所有五种经典碱基——腺嘌呤（adenine）、鸟嘌呤（guanine）、胞嘧啶（cytosine）、胸腺嘧啶（thymine）和尿嘧啶（uracil）。这些含氮分子是携带 DNA 和 RNA 遗传信息的分子「字母」。

这一里程碑与从小行星 Bennu 和 Murchison 陨石中获得的类似发现相结合，将曾经看似孤立的发现转化为具有重大意义的宇宙规律。在多个天体中持续检测到这些分子构件，表明生命前物质在太空中是广泛存在的。因此，专家们正逐渐放弃生命分子基础起源于地球本土的理论。

最终，从这些地外样本中收集的证据表明，遗传编码的关键成分是通过太空岩石输送到地球的。通过展示生命的基础字母被书写在整个太阳系的小行星岩石中，这些发现强烈暗示生命所需的生命前化学是太空的普遍特征，并随后播种了地球。

The latest discovery of nucleotides on the carbon-rich near-Earth asteroid Ryugu, from samples returned by JAXA's Hayabusa2 spacecraft in 2020, has prompted scientists to rethink how life began on Earth. A study in Nature Astronomy confirms the presence of all five canonical nucleobases—adenine, guanine, cytosine, thymine, and uracil—in the Ryugu samples. These nitrogen-containing molecules serve as the genetic "letters" that carry information in DNA and RNA.

This milestone joins similar findings from asteroid Bennu and the Murchison meteorite, transforming what once seemed like isolated discoveries into a significant cosmic pattern. The consistent detection of these molecular building blocks in multiple celestial bodies indicates that prebiotic materials are widespread in space. As a result, experts are moving away from the theory that life's molecular foundations originated natively on Earth.

Ultimately, the evidence gathered from these extraterrestrial samples suggests that the crucial ingredients for genetic coding were delivered to Earth via space rocks. By showing that the fundamental letters of life are written in rock across the solar system, these findings strongly imply that the prebiotic chemistry necessary for life is a common feature of space, which subsequently seeded Earth.