The contraceptive pill may disrupt a woman’s natural ability to choose a partner genetically dissimilar to themselves, research at the Universities of Liverpool and Newcastle has found.
Disturbing a woman’s instinctive attraction to genetically different men could result in difficulties when trying to conceive, an increased risk of miscarriage and long intervals between pregnancies. Passing on a lack of diverse genes to a child could also weaken their immune system.
Humans choose partners through their body odour and tend to be attracted to those with a dissimilar genetic make-up to themselves, maintaining genetic diversity. Genes in the Major Histocompatibility Complex (MHC), which helps build the proteins involved in the body’s immune response, also play a prominent role in odour through interaction with skin bacteria. In this way these genes also help determine which individuals find us attractive.
Dr Craig Roberts, in collaboration with Professor Morris Gosling and Professor Marion Petrie from Newcastle University analysed how the contraceptive pill affects odour preferences. One hundred women were asked to indicate their preferences on six male body odour samples, drawn from 97 volunteer samples, before and after initiating contraceptive pill use.
Dr Roberts, a Lecturer in Evolutionary Psychology at Liverpool University, said: “The results showed that the preferences of women who began using the contraceptive pill shifted towards men with genetically similar odours.
“Not only could MHC-similarity in couples lead to fertility problems but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odour perception plays a significant role in maintaining attraction to partners.”
The research, funded by the Wellcome Trust has been published in the journal Proceedings of the Royal Society B: Biological Sciences.
The paper MHC-correlated odour preferences in humans and the use of oral contraceptives. S. Craig Roberts, L. Morris Gosling, Vaughan Carter, & Marion Petrie
Reproduced courtesy of the University of Liverpool.