The base pairs that hold together two pieces of RNA, the
older cousin of DNA, are some of the most important molecular interactions in
living cells. Many scientists believe that these base pairs were part of life
from the very beginning and that RNA was one of the first polymers of life. But
there is a problem. The RNA bases don’t form base pairs in water unless they
are connected to a polymer backbone, a trait that has baffled origin-of-life
scientists for decades. If the bases don’t pair before they are part of
polymers, how would the bases have been selected out from the many molecules in
the “prebiotic soup” so that RNA polymers could be formed?