RNA (Ribonucleic Acid) strands have been found in two different species of organisms that separated from the main evolutionary group, which includes humans, a few billion years ago. Until recently, it was believed that RNA was characteristic of more evolved creatures, members of a class known as bilaterians. This evolutionary strand includes just about every animal on Earth, from worms to cows and humans.

 

The unveiling of RNA existence in basic organisms, such as the anemone (Nematostella vectensis), is a clear indication that the acid exists in virtually any living organism. This explains why dangerous mutations did not extinguish life as we know it a long time ago, as one of RNA's basic functions is to inhibit the activity of transposons, which are tiny bits of free DNA that move around the genome, causing potentially harmful mutations.

Also, scientists think it's safe to assume that, due to the acid's fine genome-tuning abilities, it greatly influenced evolution as we know it, and may have even been responsible for accelerating simple organisms towards multi-cellular life.

 

Andrew Grimson, a postdoctoral fellow, and David Bartel, member of the Whitehead Institute for Biomedical Research, Howard Hughes Medical Institute investigator and a professor of biology at the Massachusetts Institute of Technology, used high throughput sequencing of organism samples thought to be more than a billion years old. "In a relatively narrow spectrum of evolution microRNAs are often conserved. But in a broader spectrum they have completely changed. This suggests that microRNA evolution is more flexible and may be evolving more rapidly than suspected." Grimson said.

 

MicroRNA and piRNA strands have been located in both the sponge (Amphimedon queenslandica) and the starlet sea anemone, which split from bilaterian evolution millions of years ago. "Remarkably, we discovered their presence within sponge, a member of the earliest diverging group of animals." said Grimson, working in Bartel's lab at the Whitehead Institute for Biomedical Research.