Toxic Gas May Have Sparked Life on Earth Through Icy ‘Cobweb’ Crystals

Researchers at Sweden's Chalmers University of Technology report that toxic hydrogen cyanide (HCN) may have helped create the “seeds of life” on Earth. In computer models of cold environments, HCN freezes into solid crystals whose multi-faceted tips act as mini “cobweb” reactors. These icy facets are highly reactive, enabling chemical pathways not normally possible in such cold conditions. The researchers say these reactions could have started a cascade that gave rise to several building blocks of life.

Cobweb crystals drive unexpected reactions

According to the paper, the Chalmers team (Marco Capelletti, Hilda Sandström and Martin Rahm) modelled a stable HCN crystal as a 450-nanometre-long cylinder with a multifaceted gem-like tip. This shape matches cobweb-like structures seen in experiments.

The simulations identified two surface pathways that convert HCN into hydrogen isocyanide – a more reactive isomer – over minutes to days, depending on temperature. This suggests that even in icy settings, HCN could yield polymers, amino acids and nucleobases.

Implications for life and future tests

HCN is very abundant in comets and in moons like Titan, and the fact that it is found in HCN and in other molecules like it suggests that there may be a great deal more pre-biotic chemistry outside our own planet. Laboratory testing would involve grinding frozen crystals of HCN in a solution of water, increasing the surface area and testing for the presence of more complex organic molecules in sub-zero conditions. "While we may never be able to pinpoint exactly how life emerged, we can grasp how some components got formed," explains Rahm.