Scientists Increasingly Think Life on Earth Originated from Another Planet
October 15th, 2013Via: South China Morning Post:
Another origins-of-life chemist, Steven Benner of the US-basedWestheimer Institute of Science and Technology has suggested that assembling RNA would have been very difficult on the ancient earth. Speaking at a conference in August, he presented results indicating that boron and molybdenum minerals can significantly help the process. But three billion years ago, the earth was too wet and the atmosphere had too little oxygen for these minerals to have been sufficiently common and in the right forms.
Instead, Benner suggested that Mars had the right chemistry, and life may have come to earth on a Martian meteorite. “The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock,” he remarked.
Within days of Benner’s presentation, a paper was published that had reached similar conclusions regarding the “phosphate problem” – concerning the phosphorus compounds crucial for RNA, DNA and proteins. There would have been few such compounds in the water on early earth, but Martian phosphates were both more soluble and plentiful, making the “red planet” appear a better nursery for life.
Just possibly, fossil microbes have been found in meteorites from Mars. The most famous of these meteorites made world news in 1996, when Nasa scientist David McKay argued that tiny structures were fossils of life forms smaller than any known cellular life.
Meteorites from asteroids are another otherworldly source of ingredients for life. They can be rich in organic material such as amino acids, which may form as comets crash into moons or planets. After a meteor fell to earth over California in April last year, researchers at the University of Arizona gathered fragments for study. At first, they were disappointed to find few organic molecules. Then, they took insoluble material and baked it for six days in conditions akin to those around hydrothermal vents.
“And lo and behold, this meteorite left behind something we have never seen,” team leader Sandra Pizzarello told New Scientist. There were long molecular chains that can form scaffold-like structures. Rather than soapy bags, it might have been this scaffolding that trapped organic molecules which led to life.