According to a news release from the Stanford University Medical Center, the mere presence of males shortens females’ lifespan in some species.

Researchers found that males of the laboratory roundworm secrete signaling molecules that considerably shorten females’ lifespan. If executed after reproduction, scientists think this “male-induced demise” could help to safeguard resources for a male’s offspring or lower the number of mates for other males.

Though some researchers have wondered whether the physical stress of mating may result in females’ shortened lifespan, new research implies that males are executing a calculated plan at the molecular level to kill off their female counterparts after they’ve given birth.

The researchers examined the common laboratory roundworm, called Caenorhabditis elegans, or C. elegans. A normal population is made up of 0.01 to 0.1 percent males. The remainder of the population is made up of hermaphrodites.

The study reveals that males can start the killing process even across distances. As interesting as the findings are, however, it is unlikely that the results extend to mammals, as mothers are needed to raise the young.

The researchers discovered that the extended presence of young males decreased the average lifespan of C. elegans hermaphrodites by more than 20 percent. Impacted hermaphrodites also showed symptoms of aging.

Interestingly, when the researchers located hermaphrodites on laboratory dishes that had once held male worms, those hermaphrodites also displayed a shortened lifespan.

However, the researchers discovered one method of mitigating the impact.

“Males that are deficient in pheromone production no longer induce a strong premature demise of hermaphrodites,” said Anne Brunet, associate professor of genetics, “and hermaphrodites that cannot sense pheromones are resistant to male-induced demise.”

Though researchers aren’t certain how or when the males secrete the unidentified pheromones, the effect was noticeable when the researchers examined the gene expression profiles of the impacted hermaphrodites. They noticed big alterations in hermaphrodite gene expression that took place only in the presence of males. Impeding the expression of one gene in particular specifically blocked the male-induced demise.

Researchers first investigated a domesticated strain of f C. elegans, but they were also able to detect male-induced demise in a wild strain of C. elegans, as well as in two other, distantly related species of worm — verifying that the phenomenon has been conserved over about 20 to 30 million years of evolution.

The study’s findings are described in the journal Science Express.