A pair of lions apparently mating in a Botswana safari park has captured the attention of the internet — and has thrown a wrench in the argument that homosexuality is somehow unnatural.

The photograph is one in a series depicting two male lions in Botswana's Lagoon Camp area, captured last month by Nicole Cambré, a Belgian lawyer and award-winning photographer. Her full photo series can be viewed on her website.

Cambré said that despite the presence of lionesses, the two males appeared to be engaging in homosexual behavior. She recounted the experience in a statement to the Huffington Post.

"According to our guide they had only started their behaviour that same week. These intruder males had pushed out the resident males earlier in the year and the other female lions had headed into the Mopani woodlands, an area difficult to access with a safari vehicle. Only one lioness was seen in the centre of the concession where the male lions were and the lions showed no interest in the lioness leading to the assumption that she may have been pregnant. One of the lions was wearing a collar and our guide thought that they may have crossed from Namibia. It is the first time I have seen homosexual behaviour in lions but when reading about it upon my return, it is not that uncommon. With the light just around sunset, it gave some spectacular images."

Homosexuality among lions has been observed before, and it's thought that the behavior reinforces bonds and allegiances between lions. But similar behavior has cropped up in many more species.

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There's research to suggest that homosexual behavior in animals is perhaps more common than previously believed, as one 2012 Yale Scientific article posited. And in 2004, National Geographic filmmakers observed female Japanese macaques engaged in intimate activity.

"The team caught female Japanese macaques engaged in intimate acts which, if observed in humans, would be in the X-rated category," the report noted at the time.

The report also speculated that the homosexual behavior observed in the macaques may have been motivated by a more complex social impulse. "Taking something that's nonreproductive, like mounting another female — if it leads to control of a resource or acquisition of a resource or a good alliance partner, that could directly impact your reproductive success," Amy Parish, a primatologist, suggested at the time.

Whether it's to control a resource and get a leg up on reproductive success, or purely for pleasure, homosexuality in the animal kingdom is apparently far from unnatural.