The first life on land may not have dramatically stepped forth from the ocean to boldly claim the soil. Maybe, instead, it was left high and dry when its lake evaporated.
Regardless of how life became terrestrial, new data may push back scientists' estimate of when that event occurred. An international team led by scientists at Pennsylvania State University in University Park says that unusually carbon-rich rocks found in eastern South Africa provide evidence of life on land around 2.6 billion years ago.
Life on Earth dates back as far as 3.85 billion years ago (see "An early cosmic wallop for life on earth?", in this week's issue: An early cosmic wallop for life on Earth?). However, indisputably land-dwelling organisms had been previously dated to only 1.2 billion years ago, the researchers say.
The evidence for the possibly reluctant landlubbers showed up in sequential layers of carbon-rich clays within a 17-meter-thick band of rock, say