The first concerted effort to understand all the inner workings of the DNA molecule is overturning a host of long-held assumptions about the nature of genes and their role in human health and evolution, scientists reported yesterday.

The new perspective reveals DNA to be not just a string of biological code but a dauntingly complex operating system that processes many more kinds of information than previously appreciated.

The findings, from a project involving hundreds of scientists in 11 countries and detailed in 29 papers being published today, confirm growing suspicions that the stretches of "junk DNA" flanking hardworking genes are not junk at all. But the study goes further, indicating for the first time that the vast majority of the 3 billion "letters" of the human genetic code are busily toiling at an array of previously invisible tasks.