"As far as morality goes, disgust has received a lot of attention, and there has been a lot of work on it. The flip side of it is cleanliness, or being tidy, proper, clean, pure, which has been considered the absence of disgust, or contamination. But there is actually more to being clean, and having things in order. On some level even cleanliness, or the desire to feel clean and pure has a social origin in the sense that primates show social grooming: Monkeys tend to get really close to each other, they pick insects off each other's fur, and it's not just useful in terms of keeping themselves clean, but it has an important social function in terms of bonding them together."