Cosmic Rays May Be the Source
of Biological 'Handedness'
All of life's building blocks show an overwhelming bias to one form of molecular handedness, and two scientists have an interesting theory as to why.
PALO ALTO, CALIFORNIA — Interaction between cosmic rays and early life-forms may be responsible for the fundamental property of chirality, or "handedness," in biological molecules, according to a study published in The Astrophysical Journal Letters.
Showers of highly energetic, charged particles from the Sun called cosmic rays are constantly bombarding the Earth. When they hit the Earth's atmosphere, they degrade into cascades of elementary particles.
Many organic molecules such as DNA and RNA can be constructed in "left-handed" and "right-handed" versions that are mirror images of each other. In the paper, the researchers propose that the prebiotic soup on ancient Earth produced both left and right-handed versions of these nucleic acids.
Co-authors Noemie Globus, an astrophysicist at New York University, and Roger Blandford, professor of physics and of particle physics and astrophysics at Stanford University, argue that when charged particles from cosmic ray cascades reached the Earth's surface, they affected right-handed and left-handed molecules differently, giving an evolutionary advantage to one chirality. Over time this led to life dominated by a single biological handedness.
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