Iron is an indispensable condition for the development of life on Earth. The same works for other planets as well.

Scientists from the University of Oxford investigated how iron influenced the development of complex life forms. This will help you understand where other inhabited planets may be.

The initial amount of iron in terrestrial rocks is determined by the conditions of planetary accretion, during which the metal core of the Earth was separated from the rocky mantle. There is too little iron in a rocky part of the planet, like Mercury, and life is unlikely. Too much like Mars, and water is difficult to keep on the surface for the time required for complex life to develop.

John Wade, Associate Professor, Department of Planetary Materials, Department of Earth Sciences, University of Oxford

But on Earth, on the contrary, in the early days of the planet’s existence, there was enough geological iron, especially in the mantle and crust. Scientists believe that solid iron appeared on Earth thanks to meteorites. The metal partially dissolved in water, so it was abundant in the marine environment.

Later, after the Great Oxidative Event (GOE), soluble iron began to decline and the competition between cells for it increased. Organisms began to look for alternative ways to process it from dead cells, capture it from living ones or parasitize it. It is these processes that have become a stimulus for the development and evolution of living organisms, according to the authors of the work.

Our concepts hint that the conditions for supporting the emergence of simple life forms are not enough to ensure the further evolution of complex life forms. Further selection may be required by the method of serious environmental changes – for example, how life on Earth needed to find a new method of accessing iron. Such temporary changes on a planetary scale can be rare or accidental, which means that the likelihood of intelligent life emerging may be low.

Hel Drakesmith, professor of iron biology at the Institute of Molecular Medicine