A team of Canadian researchers from the University of Saskatchewan have discovered a protein in semen, dubbed the ovulation-inducing factor' (OIF), that acts as a hormonal signal on the female brain. This sends a message to the ovaries to release an egg, increasing the likelihood of conception.
Professor Gregg Adams, who led the research which was published in the Proceedings of the National Academy of Sciences, said: "The idea that a substance in mammalian semen has a direct effect on the female brain is a new one."
So far, the research team have only studied llamas and cattle, but they are now planning further research to see if OIF plays a role in human fertility.
The Daily Mail reports that they have theorised that men who produce high concentrations of OIF could be more fertile.