Exploring a Sexual Mystery (IMAGE) Kyoto University Caption A Kyoto University research team has shown that males can 'cost' less when there is a higher proportion of females, a result that may have broad implications for studies of the evolution and sustainability of sexual reproduction. Credit Kyoto University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.