Meteoric wallop may have diversified life
By Ron Cowen
Some 540 million years ago, life on Earth exploded in diversity. On the seafloor, some creatures acquired hard shells, and the direct ancestors of modern animals suddenly appeared. A new study suggests that this evolutionary Big Bang blossomed about the time that cosmic debris began pummeling our planet at an increasing rate.
The timing may not be mere coincidence, argue the geologists who found evidence for the revved-up impact rate. The researchers speculate that a spate of meteoroids battering Earth might have ferried in large amounts of the organic compounds vital to life, or the pummeling could have sparked diversity by forcing organisms to adapt to a new environment.