The Earth's ancient oceans held much lower concentrations of sulphate - a key biological nutrient - than previously thought, a new report says.
The findings paint a new portrait of our planet's early biosphere and primitive marine life.
Organisms require sulphur as a nutrient and it also plays a central role in regulating atmospheric chemistry and global climate.
"Our findings are a fraction of previous estimates and thousands of time lower than current seawater levels," said Sean Crowe, assistant professor at the University of British Columbia, Vancouver in Canada.
"At these trace amounts, sulphate would have been poorly mixed and short-lived in the oceans and this sulphate scarcity would have shaped the nature, activity and evolution of early life on Earth," he added.
To reach this conclusion, the team used new techniques and models to calibrate fingerprints of bacterial sulphur metabolism in Lake Matano - a modern lake in Indonesia with chemistry similar to Earth's early oceans.
The study was published in the journal Science.
