1. Charmaine and Maurits

2. Pheromones draw pairs of same species together Mice pheromones attract male and female with different MHC Major Histocompatibility Complex Plays important role in immune system and autoimmunity Beneficial: produce offspring with strong immune system

3. Swiss zoologist Claus Wedekind set up first experiment Recruited volunteers: 49 college women, 44 college men Wide range of MHC genes Conducted at Bern University, Switzerland

4. Asked men to wear a clean t-shirt for 2 days straight Odourless soap and aftershave Asked to remain odour neutral Sweaty t-shirt returned after two days Put into smell box with holes, one clean t-shirt as control Women asked to sniff boxes, rated them

5. Women were more attracted to men with different MHC Because women want to have varying MHCs so that their offspring will have a wide range of MHC characteristics.