It smells fishy to me

Sunday 28 June 2015

“Amines smell of rotting fish” is often quoted in chemistry textbooks. As chemists we should probably look at this the other way round and state that rotting fish smell of amines (the amine functional group is covered in sub-topic 10.1). This is because much of the the smell actually comes from the amines that are produced when the fish decays. One of the objectives of the new syllabus is to relate chemistry to other areas of knowledge. In English we have the expression “It smells fishy” when we suspect that all is not as it appears to be. Apparently this expression, or close variants of it, is common in more than twenty different languages worldwide. It would seem that the smell of amines is fairly universally linked with a suspicious nature.

Research recently published in the Journal of Experimental Social Psychology bears this out. Norbert Swartz from the University of Southern California together with David Lee and Eunjung Kim from the University of Michigan carried out an interesting experiment on 61 students. 31 of them were placed in a room that had been sprayed with fish oil and the remaining 30 were placed in a room that did not smell of fish. They were then asked various questions. One of the questions was the Moses illusion: “How many animals of each kind did Moses take on the Ark?” In repeated tests in the past using this illusion participants consistently answer “two” even when they know that Noah, not Moses, built the Ark in which all the animals went in two by two. In the test with the students in the normal room only five (17%) of the students realised that the answer is not two whereas in the room with the fishy smell 13 of the 31 students (42%) realised that the question was a ‘trick’ question. It can be interesting for chemists to question the validity of the claims made by such social science experiments, as chemists generally require reproducible results before they can form a sound conclusion. Even so, it does appear as though humans have an evolved mechanism based on the smell of amines that has helped them survive for centuries.



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