In a separate article to be published in this week's edition of the journal Science, researchers at the privately funded Celera Genomics Corporation also confirmed that the human genome contains between 26,000 and 39,000 genes. That's far fewer than what many scientists were predicting only last year when, in one of science's great rivalries, Celera and the consortium rushed to publish rough drafts of the entire human genome sequence. Instead, they have discovered that vast stretches of the code create very few genes. Researchers will spend coming months taking a deeper look. The lack of human genes poses a conundrum for scientists.
Geneticists have many possible theories.
For example, complexity may stem from combinations of genes. Since 30,000 genes can combine in far more ways than 20,000, these combinations alone may be enough to explain human complexity. Also, there's evidence that genes in vertebrates work harder by producing more kinds of proteins than the genes in worms and flies. Then there are parts of genes, known as domains, that get shuffled around into new architectures. Scientists are finding that humans have far more combinations of these architectures than simpler life forms.