Zoologist Nigel Marven tracks down the biological roots of our sensory perception in the first of a six-part series.
Smell. Marven's search for the evolutionary reasons why we find some smells vile and others delightful leads him on a tour of horrific odours around Africa and America.
Producer Jeremy Turner ; Series producer Sam Roberts BBCi: digital viewers can access special interactive options, including putting their own senses to the test, via the red button on their handset Let your senses guide you: page 35