Figure: Gene counts in a variety of species. Viruses, the simplest living entities, have only a handful of genes but are exquisitely well adapted to their environments. Bacteria such as Escherichia coli have a few thousand genes, and multicellular plants and animals have two to ten times more. Beyond these simple divisions, the number of genes in a species bears little relation to its size or to intuitive measures of complexity. The chicken and grape gene counts shown here are based on draft genomes [50,51] and may be revised substantially in the future.
But it is reassuring that our dominion over chickens extends into the genome. Read the full paper here. And while talking about chickens, check out this story of Mike the headless chicken from Barbara King's blog (also see here for the full story).