Do the Building Blocks of Life Come from Asteroids?

Scientists have discovered in samples from the asteroid Bennu the five basic elements of DNA and RNA, known as nucleobases. These molecules, essential for life on Earth, form naturally in space without the need for biological processes. This discovery strengthens the idea that the ingredients necessary for the emergence of life may have originated outside our planet.

Analyses show that Bennu contains a wide variety of nitrogen-rich organic compounds, some of which are rare in Earth’s nature. Among them are pyrimidines, a family of nucleobases, found in much greater quantities than purines, another family. This particular distribution suggests that these molecules formed in ammonia-rich environments, such as those found in the icy outer reaches of the solar system.

Researchers have also identified abundant urea, a molecule that plays a key role in the synthesis of nucleobases. Urea, combined with ammonia, promotes the creation of these elements under conditions similar to those found on asteroids. The Bennu samples also reveal traces of other complex organic compounds, such as acids and sugars, which support the hypothesis of active prebiotic chemistry in space.

The study of nucleobases and their distribution helps us better understand how these molecules form and evolve in the universe. The differences observed between Bennu and other asteroids or meteorites, such as Ryugu or Murchison, show that each celestial body has a unique chemical history. These variations depend on local conditions, such as the presence of water, minerals, or specific temperatures.

These findings confirm that asteroids could have brought essential elements to the early Earth for the emergence of life. They also open new perspectives for the search for traces of life elsewhere in the solar system and beyond. The molecules discovered in Bennu prove that prebiotic chemistry can reach a high level of complexity, even in the absence of life. This raises a fundamental question: what additional elements or conditions enabled Earth to take the step toward biology?

Official Sources

Reference Study

DOI: https://doi.org/10.1038/s42004-026-01966-z

Title: Distribution of extraterrestrial nucleobases, other N-heterocycles, and their precursors in a sample from asteroid Bennu

Journal: Communications Chemistry

Publisher: Springer Science and Business Media LLC

Authors: Yasuhiro Oba; Toshiki Koga; Yoshinori Takano; Hiroshi Naraoka; Yuta Hirakawa; Sako Sunami; Yoshihiro Furukawa; Tomoya Yamazaki; Takuto Tomaru; Jason P. Dworkin; Daniel P. Glavin; Harold C. Connolly; Dante S. Lauretta