Life teems all over our planet's exterior and even down into the lightless oceanic depths. But just how far underground might life be able to hack it?
New research offers evidence of bacteria living as deep as 12 miles (19 kilometers) underground — quite possibly the deepest life has ever been glimpsed. Learning biology's terrestrial limits, though important in its own right, is critical to understanding life's rise on other planets with far less forgiving climates and surface conditions than the Earth's.
