Our Ancestors Survived Snowball Earth
Study Shows Our Ancestors Survived Snowball Earth
Seattle WA (SPX) Jun 07, 2006
It has been 2.3 billion years since Earth's atmosphere became infused with enough oxygen to support life as we know it. About the same time, the planet became encased in ice that some scientists speculate was more than a half-mile deep.
http://www.terradaily.com/reports/Study_Shows_Our_Ancestors_Survived_Snowball_Earth.html