When scientists completed the first map of the human genome in 2004, they were surprised by how few genes they found.
In total, a human being has roughly 20,000 genes. By contrast, a poplar tree has 45,000 genes.
Most scientists had been working under the assumption that each gene produces just one message or set of instructions, so they were initially baffled by the fact that the complex human brain seemed to be governed by fewer genes than a block of wood.
But in recent years, additional studies have hinted that human genes are capable of performing far more than one trick apiece.
And this week, Canadian researchers report in the journal Nature that they have now deciphered "a code within a code" deep in the inner workings of the human genome. The hidden code contains the biological instructions that enable single genes to generate multiple messages.
Essentially, one genetic message can be rearranged or spliced with others to produced tens of thousands of different messages, said lead researcher Brendan Frey of the University of Toronto.
Dr. Frey compares the discovery of the hidden code to "hearing a full orchestra playing behind a locked door, and when you pry the door open you discover only three or four musicians generating all that music."