Complaints from men afflicted with seemingly minor ailments are often attributed to "man flu." Now scientists say that men may have been left by evolution less well-equipped to fend off disease, The Times of London reported Wednesday.

In an evolutionary twist, it appears that there is a trade-off between high testosterone levels and being able to produce a robust immune response.

The theoretical study, by University of Cambridge scientists, looked at various scenarios to test whether environmental and behavioral factors could have led men and women to evolve slightly different immune systems.

Clinical studies have found that males are more susceptible to certain infections, such as malaria, and there is some evidence for men suffering more severe symptoms and higher mortality. However, until now scientists had struggled to find an evolutionary explanation for the apparent lower level of immunity in males.

The latest study, published in the Royal Society journal Proceedings B, suggested that in some cases there could be a trade-off between developing a strong immune system and being reproductively competitive. Because males tend to compete more fiercely, this trade-off is likely to be exaggerated in men.

"If you are devoting a lot of resources to producing proteins and cells in the immune system, you may be limiting your resources for reproduction," said Olivier Restif, who led the research.

In particular, testosterone has been shown to interfere with the immune response, meaning that men with high testosterone levels are potentially at greater risk of infection. In theory, this should help females select the best men - only the strongest and healthiest would be able to afford the risk of producing lots of testosterone.

SOURCE LINK: The Times of London