India, Feb. 28 -- It all began with a simple question: How do bacteria defend themselves against viruses?

The answer was as strange as it was elegant: Bacteria develop clustered, repeated sequences in their DNA, that can remember dangerous viruses that attack them. To do this they take little mugshots, or small sections of DNA from the invaders, and stash them in their own genome, for future reference.

When biochemist Jennifer Doudna and her colleagues at the University of California, Berkeley, published the paper on their findings in 2012, it went largely unnoticed.

But it wouldn't be long before it set off a revolution in genetics.

The clustered repeated sequences that the bacteria develop were named Clustered Regularly Interspaced ...