The first lifeforms might have evolved to make use of arsenic, Felisa Wolfe-Simon of Harvard University and Paul Davies of Arizona State University suggest.

Arsenic readily forms arsenate ions and behaves like phosphorus, which binds to four oxygen atoms to form a negatively charged phosphate ion that is used to build the backbone of DNA’s double helix.

But arsenic tends to latch onto adenosine diphosphate molecules, blocking the production of ATP, and arsenic-based DNA tends to break down quickly. However, it could function in extreme cold (include other planets), they suggest, where chemical reactions move very slowly.

(Full article requires subscription)