human genome: not so promising as first thought of

The first in-depth look at the human genetic code has revealed much less than anticipated - about half to a third the number of expected genes, scientists say. Their findings so far made it clear that far from being a blueprint, the human genetic code was only a guidepost. The true directions for what makes a human being lie not in letters of code but in what the body does with that code. They have found a few interesting titbits. Most of the variation - the mutations that underlie evolution and bring gradual change - is on the Y chromosome. That means men are responsible for most mutations, because only men have a Y chromosome. They have also confirmed that there is no genetic basis for what people describe as race, and found only a few small differences set one person apart from another. "You and I differ by 2.1 million genetic letters from each other," Craig Venter, chief scientific officer at Celera Genomics Inc, which carried out one of the two studies being published, said in a telephone interview to Reuters. "Probably only a few thousand of those differences account for the biological differences between us, which means we all are essentially identical twins - even more than I thought."