This site is not maintained. Click here for the new website of Richard Dawkins.

Fossil microbes give sulphur insight on ancient Earth

Tiny structures found in 3.4bn-year-old sandstones in Western Australia represent some of the oldest, best preserved evidence of life on Earth.

Scientists say their analysis of the microfossils clearly shows the organisms were processing sulphur for energy and growth - not oxygen.

They report their discovery in the journal Nature Geoscience.

The team says the microbe remains offer a fascinating insight into conditions on the ancient Earth.

"At last we have good solid evidence for life over 3.4 billion years ago. It confirms there were bacteria at this time, living without oxygen," said co-researcher Professor Martin Brasier at Oxford University, UK.

"Such bacteria are still common today. Sulphur bacteria are found in smelly ditches, soil, hot springs, hydrothermal vents - anywhere where there's little free oxygen and they can live off organic matter," he explained.

The fossils were first identified in 2007 at Strelley Pool, a remote location of the Pilbara, a dry region about 60km west of Marble Bar.

alt text
The fossils were found in sandstones found at the base of these prominent ridges

Their host sandstones were laid down in what would have been a shallow-water beach or estuary.

They measure just a few millionths of a metre (microns) across and have been subjected in recent years to a series of advanced analytical techniques to probe their origin.

The scientists say they are now confident that the spheroidal and ellipsoidal forms buried in the rock are the remains of bacterial cells, along with the protective tubes that once housed them.

Form and behaviour are good indicators. The shape and clustering are reminiscent of bacterial cells. But more than that, the fossils are associated with tiny crystals of "fool's gold" - the pyrite mineral composed of iron and sulphur.

The types of atoms, or isotopes, present in these crystals point to the pyrite being formed as a by-product of cellular metabolism based on compounds of sulphur.

"Life likes lighter isotopes, so if you have a light signature in these minerals then it looks biological," said lead author Dr David Wacey from the University of Western Australia.

Read on

TAGGED: BIOLOGY, EVOLUTION, SCIENCE


RELATED CONTENT

Nasa's Curiosity rover zaps Mars rock

Jonathan Amos - BBC News Comments

Pew pew pew pew

Sun Is Roundest Natural Object Known

Dave Mosher - National Geographic Comments

The sun is the roundest natural object ever precisely measured, astronomers say.

Book written in DNA code

Geraint Jones - The Guardian Comments

Scientists who encoded the book say it could soon be cheaper to store information in DNA than in conventional digital devices

Prisoners pitch in to save endangered...

Ed Yong - Nature News Comments

Under the supervision of guards and graduate students, a small group of prisoners is breeding the beautiful orange-and-white insects in a greenhouse outside the prison. They have even carried out research to show what plants the butterfly prefers to lay its eggs on.

U.S. Should Adopt Higher Standards for...

- - Scientific American Comments

Teachers, scientists and policymakers have drafted ambitious new education standards. All 50 states should adopt them

17-year-old girl builds artificial...

John Roach - NBC News Comments

An artificial “brain” built by a 17-year-old whiz kid from Florida is able to accurately assess tissue samples for signs of breast cancer, providing more confidence to a minimally invasive procedure.

MORE

MORE BY JONATHAN AMOS

Nasa's Curiosity rover zaps Mars rock

Jonathan Amos - BBC News Comments

Pew pew pew pew

LHC reports discovery of its first new...

Jonathan Amos - BBC News Science &... 24 Comments

The Large Hadron Collider (LHC) on the Franco-Swiss border has made its first clear observation of a new particle since opening in 2009.

African fossils put new spin on human...

Jonathan Amos - BBC News -Science &... 23 Comments

Features seen in the brain, feet, hands and pelvis of A. sediba all suggest this species was on the direct evolutionary line to us - Homo sapiens.

Cosmic distance record 'broken'

Jonathan Amos - BBC News, Science &... 40 Comments

A cataclysmic explosion of a huge star near the edge of the observable Universe may be the most distant single object yet spied by a telescope.

Fossils may be 'earliest animals'

Jonathan Amos - BBC 8 Comments

Planck telescope reveals ancient cosmic...

Jonathan Amos - BBC 20 Comments

MORE

Comments

Comment RSS Feed

Please sign in or register to comment