1. Volume 25, Issue 19, Pages R847-R850 (October 2015)
How life shaped Earth 
Michael Gross 
Current Biology 
Volume 25, Issue 19, Pages R847-R850 (October 2015)
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2. Dead planet: While the intensive exploration of our neighbour may yet discover traces of past life, it is clear that planet Mars is much simpler in terms of mineral composition and has not been shaped by life as our planet has been for billions of years. (Photo: NASA/JPL-Caltech/MSSS.)
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3. Hollowed out: Limestone caves are caused by bacteria oxidising hydrogen sulphide to produce sulphuric acid. The image shows researchers from Penn State University at work in such a cave. (Photo: Jennifer Macalady, Penn State.)
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4. Ground work: Roots of plants help to shape and stabilise the ground they grow in, preventing erosion and influencing the course of rivers. (Photo: Richard Bardgett.)
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5. Layer cake: Banded iron formations are an early sign of life in as much as they were produced between three and two billion years ago when the anoxic oceans rich in the highly soluble ferrous iron (Fe2+) became oxidised, leading to the precipitation of ferrous iron (Fe3+), the version familiar from all things that rust. The white layers typically consist of the silicate mineral chert. (Photo: Graeme Churchard.)
Current Biology  , R847-R850DOI: ( /j.cub )
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