Aliens Among Us: Notes
Do we share our planet with alternative forms of life?
•Every living thing on earth has a deep history
•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
•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...
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