Martians in California

The discovery of a form of bacteria in a Californian lake that lives on arsenic may seem like nothing, and it certainly is in comparison with all the rumors after the publication in the technical journal Science. NASA was partly responsible after it discussed “a discovery of astrobiology that will impact in the search for evidence of alien life” — an empty phrase that, connected with the inability of amateur journalists to read it, eventually achieved its purpose of raising exaggerated or fevered expectations.

But the truth is that, once the noise went away, the discovery made by Felisa Wolfe-Simon and her colleagues of the NASA Astrobiology Institute is still substantial. It is a bacteria that is not only able to live in arsenic-polluted lakes — such as Mono Lake in California — but also to incorporate arsenic into its DNA.

This molecule, like many others that form cells, usually creates itself with the main atoms of life: carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus. In this new bacteria, arsenic can replace phosphorus and become a structural component of the double helix of DNA, which is the essence of genetic information in all living beings on Earth.

It is also true that this discovery is relevant to astrobiology, which is the discipline that seeks evidence of life on other planets in the solar system and elsewhere in the galaxy. One of the main points for this purpose is that scientists know what to look for; if alien microorganisms exist, they may not necessarily be based on the same forms of life on our planet.

Arsenic — it is perhaps the first example of poison that comes to our head — increases the list of potential basic components of biomolecules that scientists should take into account. And above all, it is a reminder of the need to keep an open mind when exploring the unknown.