With few exceptions, all known forms of life on our planet rely
on the same genetic code to specify the amino acid composition
of proteins. Although different hypotheses abound, just how
individual amino acids were assigned to specific three-letter
combinations or codons during the evolution of the genetic code
is still subject to speculation. Taking their hints from relics
of this evolution left behind in modern cells, researchers at
the Salk Institute for Biological Studies concluded that after
only two waves of "matching" and some last minute fiddling, all
20 commonly used amino acids were firmly linked with their
respective codons, setting the stage for the emergence of
proteins with unique, defined sequences and properties. Their
findings, which will be published in next week's online edition
of the Proceedings of the National Academy of Sciences, provide
the first in vivo data shedding light on the origin and
evolution of the genetic code. "Although different algorithms,
or codes, were likely tested dur