Rare Earth: Why ‘simple’ life may be common in the universe, but animals may be unique to our planet

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Cropped from: Artist’s impression of a M dwarf star surrounded by planets. Credit: NASA/JPL-Caltech

Anyone who has watched enough nature documentaries will know that life can exist pretty much anywhere on Earth. One episode of the Blue Planet II series showed a hydrothermal vent – a crack in the mid-ocean ridge where hot gases and water pour out. Bacteria thrive in the scalding water around the vents, getting their energy from chemicals like hydrogen and sulphur, and enabling a rich ecosystem of bacteria-eating crabs, shrimps, and other animals to build up to such a density that it rivals Continue reading