On the one hand, many scientists are proponents of the RNA world hypothesis for the origin of life on Earth. On the other hand, many of the same scientists believe life exists elsewhere in the universe. Indeed, many believe the universe is teeming with life.
However, if the RNA world hypothesis is true, then it's arguable the appearance of life on Earth was highly unlikely. In fact, the late chemist Robert Shapiro apparently said: "The appearance of such a molecule, given the way chemistry functions, is incredibly improbable. It would be a once-in-a-universe long shot. To adopt this [view], you have to believe we were incredibly lucky."
If life on a pale blue dot was so unlikely as to have been "a once-in-a-universe long shot," then how likely would life be elsewhere in the universe?
Given the diverse range of morphologies in life on Earth, since observed morphology is the basis for genetic relatedness between fossil remains, most scientists believe in common ancestry precisely because they recognize that spontaneous genesis of reproducible DNA isn't likely. Otherwise, they would entertain the idea that spontaneous genesis of reproducible DNA happened multiple times on Earth and evolved into different unrelated types of organisms.
ReplyDeleteHi Jim,
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