Philipp Holliger, a senior author on the study, said the work proved that two hallmarks of life – heredity and evolution – were possible using alternatives to natural genetic material.
"There is nothing Goldilocks about DNA and RNA," Holliger told Science. "There is no overwhelming functional imperative for genetic systems or biology to be based on these two nucleic acids."
Vitor Pinheiro, a co-author on the paper, said the research could help scientists unpick how DNA and RNA became so crucial in the evolution of life, and perhaps even help in the search for extraterrestrial organisms. "If a genetic system doesn't have to be based on DNA and RNA, what then do you define as life? How do you look for life?" he said.
In an accompanying article, Gerald Joyce, of the Scripps Research Institute in La Jolla, California, says the study heralds an "era of synthetic genetics, with implications for exobiology [which deals with extraterrestrial life], biotechnology and understanding life itself". He adds: "Construction of genetic systems based on alternative chemical platforms may ultimately lead to the synthesis of novel forms of life."
Other scientists, including a team at the J. Craig Venter Institute, in Rockville, Maryland, are hoping to make synthetic organisms from scratch, but the majority of the work so far has used conventional DNA.
In his article on the Cambridge study Joyce alludes to the potential dangers of synthetic genetics. He writes: "As one contemplates all the alternative life forms that might be possible with XNAs and other more exotic genetic molecules, the words of Arthur C. Clarke come to mind. In 2010: Odyssey Two, HAL the computer tells humanity, 'all these worlds are yours', but warns – 'except [Jupiter's moon] Europa, attempt no landings there'. Synthetic biologists are beginning to frolic on the worlds of alternative genetics but must not tread into areas that have the potential to harm our biology."
Intellpuke: You can read this article by Guardian Science Correspondent Ian Sample in context here: www.guardian.co.uk/science/2012/apr/19/dna-alternative-xnas-science-genetics