Life out of death

Perhaps Agatha Christie would have been intrigued by this piece of new research.

The chemistry of life revolves around six key chemicals. Carbon, oxygen, hydrogen, nitrogen, phosphorus and sulphur make up the major ingredients of many of our body's building materials.

However, from the bottom of a lake in California comes a bacteria that uses arsenic as a substitute for phosphorus. Arsenic has a similar size and charge to phosphorus which makes the switch possible and this in turn presents interesting discussion points. If phosphorus can be substituted then what else? Could there be an entirely different system of life out there based on different elements?

Whilst this is a genuinely novel discovery it is unlikely that it can be extended so far. For a start even this finding has its limits:

It is thought that downstream metabolic processes are generally not compatible with As-incorporating molecules because of differences in the reactivities of P- and As-compounds. These downstream biochemical pathways may require the more chemically stable P-based metabolites

This microbe probably represents the outer fringes of what makes up the biosphere, rather than the doorway into another world of possibilities.