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

Gene That Once Aided Survival in the Arctic Found to Have Negative Impact on Health Today
2014 10 23
In individuals living in the Arctic, researchers have discovered a gene variant that arose thousands of years ago and most likely provided an evolutionary advantage for processing high-fat diets or for surviving in a cold environment; however, the variant also seems to increase the risk of hypoglycemia, or low blood sugar, and infant mortality in today’s northern populations. {snip} “Our work ...
The Ebola hoax: questions, answers, and the false belief in the “One It”
2014 10 23
“The Reality Manufacturing Company doesn’t just sell ‘fake paintings’ that are easy to spot. No. They also sell images that are geared to mesh with people’s deeply held instincts and thereby produce rigid false beliefs. People are sure that if they gave up such beliefs, their world would fall apart and blow away in the wind.” ...
New Controversial Theory Suggests "Hobbits" Were Not Human - Who Were These Mysterious Beings?
2014 10 23
The origin of the Hobbit species remains a challenging subject to scientists. The Hobbit’s discovery confirmed the view that the Earth was once populated by many species of human, but new research the Hobbit’s were not human at all! So, who were these mysterious beings? Where did they come from? The idea that our species, Homo sapiens, was the only species of human on ...
Right into enemy hands? ISIS shows off new weapons allegedly airdropped by US (VIDEO)
2014 10 23
Islamic State has published a new video in which a jihadist shows off brand-new American hardware, which was purportedly intended for the Kurds they are fighting in the Syrian border town of Kobani. The undated video, posted by the unofficial IS mouthpiece “a3maq news”, sees a jihadist showing several boxes of munitions with English-language markings, with a parachute spread out on ...
STAGED INFECTION: Has The Ebola ‘Outbreak’ Narrative Fallen Apart?
2014 10 22
Over the past month, the ‘pandemic’ propaganda surrounding the deadly Ebola virus seemed to reach vitriolic levels – raising serious questions about the validity of this current viral outbreak… On Monday of this week, it was reported that 48 people were released and cleared after a 21-day quarantine due to their contact with the now deceased Ebola-stricken patient Thomas Eric ...
More News »