Microbial genes in the human genome: Lateral transfer or gene loss?

The human genome was analyzed for evidence that genes had been Laterally tr ansferred into the genome from prokaryotic organisms. Protein sequence comp arisons of the proteomes of human, fruit fly, nematode worm, yeast, mustard weed, eukaryotic parasites, and all completed prokaryote genomes were perf ormed, and all genes shared between human and each of the other groups of o rganisms were collected. About 40 genes were found to be exclusively shared by humans and bacteria and are candidate examples of horizontal transfer f rom bacteria to vertebrates. Gene Loss combined with sample size effects an d evolutionary rate variation provide an alternative, more biologically pla usible explanation.