It’s not just about people. Researchers are working to unravel not only the human genome but also the genome of other species, as well. Cats, for example, seeing as they have shared households with humans for an estimated 9,000 years. Researchers at Washington University School of Medicine in St. Louis led an international team that sequenced and analyzed the cat genome to better understand the animal’s domestication. Their report appeared in the Proceedings of the National Academy of Sciences Early Edition. They found changes in the genes of domestic cats that other studies have shown are involved in behaviors such as memory, fear, and reward-seeking. Cats rely less on smell to hunt than dogs—and scientist found fewer genes for smell in cats than dogs. However, they identified genes related to an alternate form of smell that detects chemicals called pheromones, which allow cats to monitor their social environment, including seeking out the opposite sex. This ability is not as important to dogs, which tend to travel in packs. But it is crucial in cats, which are more solitary and may have more difficulty finding mates.