¢What if other, completely distinct forms of biology also took root on the early Earth? ¢Consider how quickly life appeared here ¢What if life arose on Earth more than once? With their own biochemistry and separate evolutionary history? ¢What if one or more of those alternative forms of life is still around? ¢At ï¬rst, this idea may sound crazy
¢Its generally believed that our DNA-based ancestors drove any competitors to extinction ¢Another idea is that scientists are not looking hard enough ¢Steve Benner, Foundation for Applied Molecular Evolution in Gainesville, FL said These sorts of were the center of the universe arguments have always failed. ¢Benner believes these non-DNA-based organisms are hiding here on Earth today (with a primitive biochemistry)
¢Researchers now believe that DNA came from an RNA-based parent (s) ¢RNA can cut apart molecules and put them together, working as DNA storage and an enzyme ¢He believes that 4 billion years ago simple RNA-based organisms lived here; they developed the ability to build proteins and switched to 2 strand DNA ¢The evidence of these RNA organisms is in our own cells ¢Benner is testing his theory by building RNA organisms from scratch
¢One way RNA organisms might have survived is by thriving in places DNA organisms cannot
¢RNA organisms may be much smaller, allowing habitation of rock pores for example ¢Even if RNA life were living out in the open, the life deciton tools that we have today would not ï¬nd it, Benner says. ¢Davies is entertaining the idea that life might have begun more than once on Earth ¢His colleague estimate that theres a 95% chance that life could have existed and died out 2 or more times already ¢The giant impact on the early years of Earth is thought to have wiped out previous life forms, but the possibility that some survived cannot be ruled out
¢A microbe-bearing rock could have been blasted onto Venus or Mars, starting life there; an impact on those planets could have done the same, transferring the life back to Earth ¢The RNA organisms would had to eventually battle with the DNA organisms over living space ¢Recent estimates say the number of microbes in the ocean is 360 octillion (360,000,000,000,000,000,000,000,000,000) ¢Today scientists are manipulating DNA to create new kinds of organisms ¢All organisms genes are built with a 4 letter DNA. Chemists can create other alphabets ¢Engineered bacteria now use amino acids that have never existed in nature to build proteins.
¢Engineering organisms vs searching for organisms
¢With inadequate tools, Its like looking for a common English phrase in a book written in French; youre not going to ï¬nd it says Davies ¢December 2006 was Davies ï¬rst meeting with like-minded scientist on the topic of multiple origins of life ¢Desert varnish is a mysterious coating, unexplainable by ordinary chemistry, and worthy of researching for alternate forms of DNA ¢If you could eliminate life as we know it and something was still growing, that might be life as we dont know it Davies says. ¢Process of elimination involves putting organisms in a petri dish and trying to kill them ¢NASA has put the funding into Moon missions instead of searching for foreign life forms