> "The researchers said that seven species of bacteria were found in the frozen water in 2012. The DNA match to any known organisms never went past 86 percent,

> "The researchers said that seven species of bacteria were found in the frozen water in 2012. The DNA match to any known organisms never went past 86 percent, so it is considered to be an unknown form of life. Anything under 90 percent is considered enough to designate a new species." Is that 90% figure standard convention? Where did it come from? I'm not too familiar with this field, so is that basic textbook stuff? It seems arbitrary.