The public consortium that published in mid-February its first draft of the sequence and analysis of the human genome found 200 genes that resembled genes in certain bacteria but didn't resemble genes in other animals or yeast. The researchers speculated that these 200 or so genes were transferred by bacteria to human ancestors fairly recently in evolutionary time. This finding made the "Top 10 Surprises" list of the researchers.

This month researchers associated with the competing team of human genome sequencers challenged that finding and the accompanying interpretation. They reported that they found genetic homologs or cousins to the 160 of the 200 genes in lower animals, such as the nematode C. elegans and the fruitfly.

These researchers argue that since the genes are present in humans, flies and nematodes, then it's likely that the genes have been present all along through evolution, and that there is no need to invoke transfer of the genes from bacteria directly to human.

Researchers from both camps will now likely be asking, "How similar is similar enough?" when comparing the 200 genes with genes from other organisms. This will be analogous to debates between linguists studying the origins and evolutions of words. A key issue will be deciding just how to weigh the similarity between two sequences.