In mid-January, a group of computer scientists and biologists from the University of Vermont, Tufts, and Harvard announced that they had created an entirely new life form — xenobots, the world’s first living robots.

Where Will The Next Pandemic Come From? And How Can We Stop It? | Popular S

Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, we show that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. We also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution, two hallmarks of life, are not limited to DNA and RNA but are likely to be emergent properties of polymers capable of information storage.

According to this view, ancient viruses, as with the ones today, could only make copies of themselves by succesfully infecting a host. So they become engines of innovation, using every possible dodge to get their genetic payload inside the host cell. In an early, RNA-protein world, there would not be enzymes to degrade DNA, so a virus encoded by DNA would have a big survival advantage. This suggests a scenario in which a clever parasite brings along DNA plus the means of copying DNA-- a different parasite at least for bacteria and archaea/eukaryotes-- and hijacks the cell's existing interpretation equipment. The symbiosis of virus plus RNA/protein cell eventually resulted in the modern arrangement of DNA, RNA and protein.

One of the most beautiful aspects of the genetic code is its simplicity: three letters of DNA combine in 64 different ways, easily spelled out in a handy table, to encode the 20 standard amino acids that combine to form a protein.

But between DNA and proteins comes RNA, and an expanding realm of complexity. RNA is a shape-shifter, sometimes carrying genetic messages and sometimes regulating them, adopting a multitude of structures that can affect its function. In a paper published in this issue (see page 53), a team of researchers led by Benjamin Blencowe and Brendan Frey of the University of Toronto in Ontario, Canada, reports the first attempt to define a second genetic code: one that predicts how segments of messenger RNA transcribed from a given gene can be mixed and matched to yield multiple products in different tissues, a process called alternative splicing. This time there is no simple table — in its place are algorithms that combine more than 200 different features of DNA wit