( gs prevent homo-DNA from taking onthe ...)Uncovering DNA's 'sweet' secret

The findings suggest that fully hydroxylated six-carbon sugars probably would not have produced a stable base-pairing system capable of carrying genetic information as efficiently as DNA.

"The structure now provides insight of a chemical nature that (the six-carbon sugar) is just too 'bulky.' It has too many atoms," Egli said.

The new insights provided by this structure lie at the heart of the most fundamental of scientific inquiries - the origin of life on Earth. If the pieces of DNA and RNA hadn't come together just so, life as we knowit would not exist.

Although Egli's structure has ruled out six-carbon sugars as viable alternatives for the sugar backbone of DNA, the existence of a plethora of sugars - as well as alternative bases - make for an almost endless number of possibilities from which nature selected the winning DNA combination.

"Homo-DNA is just one alternative system. There are hundreds of sugars, as many as you can think of. It will be almost impossible to look at all of them," Egli said.

"But the big red herring of this work could be that nature never went through these other sugars. Maybe it just hit on gold (these five-carbonsugars) very early and took off from there."