Males more jealous when wife or girlfriend is fertile, researchers say
and World Science staff
Men become more jealous of dominant males when their female partner is near ovulation, and thus at her most fertile, researchers have found.
The scientists said this may reflect an evolutionary mechanism in which males become more competitive during the prime times for mating.
Previous studies had found that women’s preferences for male appearance vary with their fertility, said the researchers, Rob Burriss and Anthony Little of the University of Liverpool, U.K. During ovulation, when the ripe egg is released from the ovary, women tend to find masculine looking men more attractive and prefer their voices and odor.
During this phase, Burriss and Little said, past studies had also shown that women are more prone to have an affair with a masculine-looking man. Such an appearance is linked to high levels of the hormone testosterone, social dominance and good genetic qualities that can be passed on to offspring.
The new study, they added, has found that men sense this preference shift in their female partners and find masculine men more threatening during their partner’s most fertile phase.
The experimenters showed men images of male faces that were either high or low in “dominant features,” such as a strong jaw lines and thinner lips. The viewers were asked to rate each image for dominance, a dominant person being defined as someone who looked like they could “get what they wanted.”
The viewers normally rated the faces as more dominant if at the time, the viewer’s partner was near ovulation, the researchers found. But this effect disappeared if their partners were using oral contraception, in which case they would have been less fertile.
Participants were asked to provide information on whether or not their female partner used oral contraception and the date of her current or previous menses.
“Groups of animals, such as chimpanzees, can live quite happily together, but when a female is ready to mate the two dominant males within the group become rivals and fight for her attention,” Burriss said.
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