In the animal kingdom, wild creatures are quite literally hard-wired to locate suitable mates and work as quickly as possible to ensure reproductive success. But one thing scientists have long wondered about is how sexually transmitted diseases (STDs) play into wild animals’ instinctive thinking. More specifically, do wild animals discriminate against potentially infected mates?
Based on the results of a study that was published just this past week in the journal Science Advances, that may very well be so. The researchers reached this conclusion after scrutinizing the multitude of failed mating attempts by infected olive baboons at Tanzania’s Lake Manyara National Park.
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At this particular park, a subset of both males and females in a study group comprising of roughly 170 olive baboons were infected with Treponema pallidum, a pathogen known to cause genital ulcers, skin lesions, and other discomforting effects. Given the high visibility of these conditions, it may come as no surprise that some baboons took notice when a potential mate exhibited one of them.
While not every olive baboon in the study group exhibited the STD, a small subset did, and among that small subset were both females and males. Out of those infected, the researchers learned that the females were the most unwilling to participate in intercourse with an infected partner. Similarly, females avoided intercourse if they themselves were infected, even if the male wasn’t.
"Our findings indicate that the risk of contracting a sexually transmitted disease can produce individual behavioral changes that could lead to a change in partner choice and potentially reduce the degree of promiscuity in a nonhuman primate population," elucidated Dietmar Zinner, a co-author of the paper.
Perhaps unsurprisingly, this conscious mating avoidance on the female olive baboons’ part wasn’t shared by their male counterparts. Whether it was the male or the female that was infected, males still tried their hardest to copulate with other females, seemingly ignoring the potential risk of contracting the disease for themselves.
Over the course of the 18-month science experiment, the researchers witnessed this polarizing behavior between female and male olive baboons time and time again. Out of 876 total mating attempts, which were mostly initiated by males, just 540 resulted in successful copulation. Most of the time, failed copulations involved the presence of a clearly visible STD infection, either by the female or the male.
The results are particularly fascinating because similar patterns occur in humans, and perhaps even in other animal species. With further research, scientists may determine whether other animal types exhibit similar behavior in an effort to distinguish suitable mates from others.