A little known sexually transmitted infection can boost the survival of patients infected with HIV—a more dangerous virus, researchers say. GB virus C (GBV-C) is the only known case of a potentially beneficial STI in humans. But it’s an example of a phenomenon that scientists are beginning to see elsewhere: STIs that are good for your health. What’s more, the health benefits of these helpful STIs could have given a boost to the evolution of promiscuity, scientists say.
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The more sex that individuals have, the more likely they are to pick up an advantageous STI. The increased survival rates could help explain the evolution of promiscuous behavior, which is widespread among the animal kingdom, Smith says. There are limits to this idea, however, says Joël White, an evolutionary ecologist at the University of Toulouse in France who was not part of this study. Other factors that also provide evolutionary advantages are likely to have a stronger influence, he notes. For example, mating with several partners increases the chances that females will become fertilized by a top-notch male.