Guest Post: Life on Mars – revisited

Martian rover (NASA) crop
NASA

Are we alone in the Universe? This question has teased scientists and philosophers for many decades and is a central theme in much science fiction writing. More recently, as planets have been discovered in solar systems other than our own, the question has returned. Could there be another Earth-like planet colonised by living organisms out there somewhere? This field has become so important scientifically that it is now regarded as a separate discipline – that of astrobiology. Continue reading

Guest Post: A hostile start to life on Earth

volcano-1784656_1280-pixabay.jpg
Pixabay

Life on Earth had a rocky start – literally. For hundreds of thousands of years the planet was a hellish place. This period in geological history is called ‘Hadean’, and it was thought that no living thing could have survived. Life emerged so soon after Earth cooled that scientists have wondered how it could have been possible – but new results this year tell a different story. Continue reading

Guest Post: Making the Molecules of Life

geothermal ChampagnePool-Wai-O-Tapu_rotated_MC Christian Mehlführer wikimedia ccc2.5 crop
© Christian Mehlführer, Creative Commons Attribution 2.5 Generic license

At what point did chemistry become biology? In what type of environment did this transformation take place? These are major questions for those seeking to understand the origins of life on Earth. Continue reading

Guest Post: Life as old as the Earth? The earliest evidence for living things

stromatolite-fossil-james-st-john-flickr-ccc2.jpg
Cross-section of a fossil stromatolite © James St John, flickr, https://creativecommons.org/licenses/by/2.0/

The history of life on Earth is almost as long as the history of Earth itself. The most precise scientific dating methods tell us that our planet formed 4567 million years ago, although there are no rock samples preserved from this ancient and chaotic time. The oldest known Earth materials are about 4300 million years old, and are found in the remote deserts of western Australia. The oldest probable evidence for life on Earth has been dated between 3700 and 3800 million years, in west Greenland, and is so sophisticated that the history of life on earth must extend much further back. These observations suggest that life is a fundamental property of our planet, a feature which makes the Earth very different from its immediate rocky neighbours. Continue reading