Time-Traveling Sex Partners May Be Bad for Your Health, Scientists Say

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Michael  J. Fox met his mother and endangered his own existence in the movie "Back to the Future."

She may have been more hazardous to his health than he realized.

Evolutionary ecologist Nicolas Rode of the Center for Functional and Evolutionary Ecology in Montpellier, France, and his colleagues discovered that mating with time-traveling partners can shorten one's lifespan, Discover Magazine noted.

The time-travelers in the study are brine shrimp (more commonly called Sea-Monkeys), because the hardy shrimp eggs can survive for years when dehydrated before hatching into healthy young when water returns. Rode and his colleagues gathered eggs from the Great Salt Lake in Utah from sediment layers they dated to 1985, 1996, and 2007. They brought them back to the lab, reared brine shrimp, and mated females with males from their own time as well as from the other years.

Rode and his colleagues discovered that having sex with males from another time is bad for a brine shrimp’s health. The further away in time they were, the sooner the female creatures died, Discover reported.

When the male traveled 22 years to mate with a female, her life was cut short on average by 12 percent.

Why? In many species, males and females have conflicting evolutionary interests. Males compete with each other to fertilize females, and evolve a variety of techniques to ensure success: They put scrapers into females to dump out the sperm from previous males, and they inject “anti-aphrodiasiacs” to make females unreceptive to other males. Females strive to live longer, despite these dangerous male devices.

If sexual conflict is an ongoing evolutionary process, you’d expect females to fare differently with males from different time periods -- and indeed, they did, though the scientists were unclear about exactly how the males were harming the females.

Read more science stories in Discover Magazine.