If we could eradicate disgust, would global warfare disappear? That is the intriguing thesis of Marc Hauser [4], Professor of Psychology at Harvard University and contributor to Edge (www.edge.org [5]), a discussion forum for some of the world’s leading scientists.

Every year, Edge contributors are asked to consider an open-ended question. In his response to this year’s poser — What are you optimistic about, and why? — Hauser suggests that science may be able to rid the world of prejudices such as racism and sexism. These "isms" are fuelled not only by the perception of difference, but by the systematic denigration of others.

Pivotal to this process is disgust. Some aspects of this emotion are common to all cultures (an aversion to faeces and urine) but others are culture-specific. The agreeability of consuming sheeps’ eyeballs or chicken’s feet, for example, varies between countries.

Hauser calls disgust a "mischievous emotion", stretching beyond the purpose for which it originally evolved (most probably to keep us away from disease-carrying substances) and leaking into other arenas, such as the construction of social hierarchies. Look at the Indian caste system — the Dalits, or untouchables, perform the dirtiest work (such as handling dead animals or human excrement), live apart from polite society and, in some rural regions, are still banned from temples. ... [6]