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Aliens Among Us Essay

•Earth is 4.5 billion years old, uninhabitable for the 1st 6 million •3.8 billion years ago is when life began to emerge more and more •All living organisms use DNA to encode their genetic info •They all use RNA •“In short, every species seems descended from a common ancestor whose attributes define what scientists mean when they say ‘life as we know it’.”

•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 first, 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 ‘we’re 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

•Page 2

•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 find it,’ Benner says.” •Davies is entertaining the idea that life might have begun more than once on Earth •His colleague estimate that there’s 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.”

•Page 3

•Engineering organisms vs searching for organisms

•With inadequate tools, “‘It’s like looking for a common English phrase in a book written in French; you’re not going to find it’” says Davies •December 2006 was Davies first 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 don’t 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


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