Hugh Pickens writes: "Evidence that the smell of fear is real was uncovered by US scientists last year who studied the underarm secretions of 20 terrified novice skydivers and found that people appear to respond unconsciously to the sweat smell of a frightened person. Now the Telegraph reports that researchers hope a ''fear detector'' will make it possible to identify individuals at check points who are up to no good. ''The challenge lies in the characterization and identification of the specific chemical that gives away the signature of human fear, especially the fear in relation to criminal acts," says Professor Tong Tun at City University London who leads the team developing security sensor systems that can detect the human fear pheromone. The project will look at potential obstacles to the device, such as the effects of perfume and the variances in pheromone production and if the initial 18-month feasibility study is successful, the first detectors could be developed in the next two to three years. ''I do not see any particular reason why similar sensor techniques cannot be expanded to identify human smells by race, age or gender to build a profile of a criminal during or after an incident,'' Tong added."