Melbourne: Men who exhibit 'mate guarding' behaviours, such as staying close to their wives and girlfriends at a party or gifting them jewellery, are more likely to have poorer-quality sperm than males who do not do so, a new study has found.

Researchers from the University of Western Australia studied 45 men in committed heterosexual relationships about their mate guarding actions and analysed their ejaculate samples.

They found that men who performed fewer mate guarding behaviours had a greater concentration of sperm, a higher percentage of motile sperm and sperm that swam faster and less erratically than men who performed more mate guarding behaviours.

While mate guarding behaviour is linked to sperm quality in birds and fish, the study is the first to investigate the relationship in humans, according to Samantha Leivers, who conducted the research at UWA.

Leivers said mate guarding in humans is quite broad and can include anything from physically defending a partner to giving flowers, jewellery or an engagement ring.
Leivers said it is unclear from the study whether sperm quality is plastic (dependent on situational factors) or fixed when it comes to mate guarding, 'medicalxpress.com' reported.

She said men who are unable to mate guard due to circumstances such as long distance relationships or a partner that does not allow mate guarding, may experience a plastic effect that improves his sperm quality.

"Once he's able to start mate guarding more, maybe the sperm quality would decrease," Leivers said."Another idea is that it's actually fixed, in that men who naturally have lower quality sperm basically increase their chances of paternity through the mate guarding.
"So if they have low quality sperm there is just this innate response that they have to increase their mate guarding behaviour," she said.

The study is published in the journal PLoS ONE.