Study turns back clock on origins of life on Earth
2009 05 25

By Julie Steenhuysen | Reuters.com


The bombardment of Earth by asteroids 3.9 billion years ago may have enhanced early life, according to a new University of Colorado study. Credit: NASA/JPL


A heavy bombardment by asteroids the size of Ireland was not enough to wipe out life on Earth 3.9 billion years ago, researchers said on Wednesday in a finding that turns back the clock of life by 500 million years.

Many scientists had thought the violent pelting by massive asteroids during the period known as the Late Heavy Bombardment would have melted the Earth's crust and vaporized any life on the planet.

But new three-dimensional computer models developed by a team at the University of Colorado at Boulder shows much of Earth's crust, and the microbes living on it, could have survived and may even have thrived.

"These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago," said Oleg Abramov, a researcher at the university whose study appears in the journal Nature.

"It opens up the possibility that life emerged as far back as 4.4 billion years ago, about the time the first oceans are thought to have formed," Abramov said in a statement.

To study this period, Abramov and colleague Stephen Mojzsis used data from moon rocks, meteorite samples and the dented surfaces of neighboring planets to develop a three-dimensional model of this period of bombardment.

"What we did was recreate the Late Heavy Bombardment on a computer," Abramov said, adding that the simulation randomly "smacked the Earth" with giant asteroids.

The team then looked at the impact that would have had on the Earth's temperature in the so-called geophysical habitable zone -- a zone representing the top 2.5 miles of the Earth's crust.

Based on these models, Abramov said this sustained period of impacts would have killed any life on the Earth's surface, but not all life on Earth, as many had assumed.

"We find it is essentially impossible to sterilize the entire habitable zone of the Earth by this kind of bombardment," Abramov said in a telephone interview.

"Certainly, the surface of the Earth was sterilized repeatedly," he said.

But he said hydrothermal vents below the surface of the Earth may have offered sanctuaries for certain heat-loving microbes, and may have even provided a kind of incubator for life.

He said many scientists had thought that a cataclysmic bombardment event would have sterilized the planet and life would have had to start anew.

"The important thing about these results is they push back the possible beginnings of life as we know it," he said.

"Exactly when life originated on Earth is a hotly debated topic," said Michael New, an astrobiologist at the National Aeronautics and Space Administration, which sponsored the research.

"These findings are significant because they indicated life could have begun well before the Late Heavy Bombardment, during the so-called Hadean Eon of Earth's history 3.8 billion to 4.5 billion years ago," New said in a statement.

(Editing by Michael Conlon and Doina Chiacu)

Article from: www.Reuters.com




Related Articles
Dinosaur Killer May Have Been Volcanism, Not Asteroid
New Insight into Earth's Early Bombardment
Holes in the Earth: 170 and Counting
Greatest Mysteries: How Did Life Arise on Earth?
The Asteroid Paradox: Harm or Help? [Video]


Latest News from our Front Page

Secret underground tunnels of ancient Mesopotamian cult revealed under Ani ruins
2014 09 01
For the first time in history, the academic world is paying attention to the spectacular underground world of Ani, a 5,000-year-old Armenian city located on the Turkish-Armenian border. Hurriyet Daily News reports that scientists, academics, and researchers have just met at a symposium in Kars titled ‘Underground Secrets of Ani’ to discuss the city’s underground world mentioned in ancient ...
A Government Vision Of The Future That Isn’t That Great
2014 09 01
Here’s a report by the UK Ministry of Defense, a document that they’re not hiding - it’s not classified. In fact, they WANT you to read it: the Global Strategic Trends 2045. For your convenience, they’ve even produced a handy video about their dire predictions: They present a warning call for how things are going to be bad in the future. ...
Bad Memories Turned to Happy Ones in Mice Brains
2014 09 01
Memories are often associated with emotions, and these feelings can change through new experiences and over time. Now, using light, scientists have been able to manipulate mice brain cells and turn the animals’ fearful memories into happy ones, according to a new study. Memories are encoded in groups of neurons that are activated together or in specific patterns, but it is ...
CIA MKULTRA: they intended to use drugs for “everything”
2014 09 01
Drugs to transform individuals…and even, by implication, society. Drug research going far beyond the usual brief descriptions of MKULTRA. The intention is there, in the record. A CIA document was included in the transcript of the 1977 US Senate Hearings on MKULTRA, the CIA’s mind-control program. The document is found in Appendix C, starting on page 166. It’s simply labeled “Draft,” dated 5 May ...
Harmful Compound Found in Many BPA-Free Bottles
2014 09 01
A chemical found in many products labeled “BPA free” may produce many of the same health problems as the original chemical, including hyperactivity and cardiac arrhythmia, according to a pair of studies presented recently at the joint meeting of the International Society of Endocrinology and the Endocrine Society in Chicago. “BPS, termed the safe alternative to BPA, may be equally as ...
More News »