You Owe Your Life to Rock
Thank goodness for granite. If not for the formation and subsequent erosion of large quantities of metal-rich granite on a supercontinent that formed billions of years ago, the evolution of multicellular lifeâ€”including usâ€”could have been stifled or delayed, according to a new study.
For much of its history, life on Earth existed as only single-celled organisms. Certain proteins critical for multicellular life, and presumed to have been equally critical for its evolution from single-celled ancestors, require heavy-metal elements, especially copper, zinc, and molybdenum, says geoscientist John Parnell. Previous studies suggest that multicellular life evolved sometime between 1.6 billion and 1.2 billion years ago. Researchers thought that before that innovation, these vital metals were locked away from environments where life thrivedâ€”either sequestered in the oxygen-poor depths of the ocean or held in ancient ore deposits in Earth’s crust, waiting to be eroded. Now, Parnell and his colleagues have proposed another option that fits new geological evidence: The essential metals eroded from a rare type of granite that formed in large amounts soon after Earth’s landmasses collided to create the supercontinent Nuna, about 1.9 billion years ago.