That's the bold and controversial theory of Chandra Wickramasinghe, an astrobiologist at Cardiff University in the United Kingdom, who insists that life on Earth started after a comet filled with a warm and watery clay pool collided with the Earth, creating a perfect environment for organic molecules to be transformed into living creatures.
Wickramasinghe and his team say the proof is in the math. They have calculated that it is one trillion trillion times more likely that life started inside a slushy comet than on Earth, reports Space.com. "The comets and the warm watery clay pools in comets are settings in which the organic molecules are transformed into living structures in comets," Wickramasinghe told Space.com. "That transformation is more likely in some comet somewhere in the galaxy than in any small pond on the Earth."
Not so fast! Even though the findings have been published in the prestigious International Journal of Astrobiology, not everyone is convinced this theory is right. Many scientists do think that comets could have delivered some of the water and organic materials necessary for life on Earth; however, their agreement with Wickramasinghe ends there, insisting his theory is speculative and without hard evidence. "It is a theory built on air, not solidly grounded in scientific facts," David Morrison, a senior scientist at the NASA Ames Research Center in Moffett Field, California, who was not involved in the study, told Space.com.
How could a comet be the building block of life on Earth? Wickramasinghe's theory is based on the idea that comets are filled with porous clay particles that can hold water in liquid form--for just about forever. While some comets may be like this, it doesn't fit the description of all comets. The "assumption that Earth has very little clay while comets are full of clay is the key to their argument, and it is at best speculation," Morrison insisted to Space.com.
No matter what is inside a comet, Paul Falkowski, a biochemist at Rutgers University in New Jersey, doesn't think the origin of life can be solved with a mathematical calculation. "These basic kinds of things are dependent on the beginning initial assumptions. I don't know that we know the odds," Falkowski explained to Space.com. "We know the odds for exactly one planet, and it happened once, so everything else is a game." In fact, Falkowski thinks that DNA could only survive a few hundred thousand years in space, which rules out the idea that comets could have been the key to populating the Earth.
--From the Editors at Netscape
