Life on land began billion years 'earlier'
LONDON (Reuters) - Life on land began more 1.4 billion years earlier than
scientists had thought, geologists have said.


Scientists have known that micro-organisms have lived in oceans for about 3.8
billion years, but they weren't sure when early life forms made the
transition to land.


The oldest proof of terrestrial life had been found in 1.2 billion-year-old
fossils from Arizona, but scientists in South Africa and the United States
have now discovered organic matter in 2.6 billion-year-old South African
rocks.


"This places the development of terrestrial biomass more than 1.4 billion
years earlier than previously reported," Yumiko Watanabe, of the Pennsylvania
State University, said in a study in the science journal Nature.


Knowing when micro-organisms made the transition from oceans to land is
important because it gives scientists new information about the presence of
oxygen that is needed to sustain life and the formation of the earth's
protective ozone shield.


Hiroshi Ohmoto, a geochemist at Penn State who contributed to the research,
believes there are even earlier samples of life on land.


He and his colleagues are planning to scour sites in Australia, Canada and
elsewhere to find them