Plate tectonics may have triggered evolution of life on Earth

New Scientist : The breakup of the supercontinent Pangaea some 125 million years ago may have provided the environment necessary to generate life deep in Earth’s oceans. Frieder Klein of the Woods Hole Oceanographic Institution in Massachusetts and his colleagues examined rock samples collected from beneath the sea floor off Portugal and found that they contain a sizable percentage of organic material—about 0.5% by weight—as well as amino acids, proteins, and fatty lipids. The researchers say that hydrogen- and methane-rich hydrothermal fluids were abundant in Earth’s mantle, and as Pangaea broke apart, ocean water seeped into the rock’s fissures and cavities. Oxygen, sulphates, bicarbonates, and other materials in the seawater reacted with the mantle material to fuel the growth of microbial communities. Moreover, conditions similar to those that created the microbes found by the researchers may have also spawned the first life on Earth some 3.5 billion years ago. And those same conditions may exist elsewhere in the solar system, says Klein.