Roughly 200 years after being tamed, bred and adopted as science’s favourite laboratory animal, the brown Norway rat has had its genome sequenced. It is only the third mammal after humans and mice to have its genetic plan read.Researchers say the feat will allow important human genes to be tracked down more quickly, for example those related to cardiovascular disease or behaviour, and will speed the creation of treatments for diseases. Comparisons between the genomes is also yielding tantalising insights into how each species evolved. The analysis has already shown, for example, that rats have been evolving faster than both humans and mice. “We find that rodent evolution is an order of magnitude faster than in humans,” says Richard Gibbs of the Baylor College of Medicine in Houston, Texas, and head of the sequencing effort.The regions evolving fastest are those associated the rat’s acute sense of smell and its use in detecting danger, marking territory and choosing mates. Rats have an estimated 2070 smell receptor genes, about a third more than mice, and also make more “pheromone” scents.
