Pictures of two "male" lions mating in the wild have made a sensation online, but the truth may be even more intriguing.

The lion on the bottom is more than likely a female African lion with a mane, a type of animal regularly seen in northern Botswana, where Nicole Cambré recently photographed the lions on safari.

One of the photos shows the two animals rubbing their heads against each other, which is not unusual behavior for males as part of a dominance display, notes Kathleen Alexander, an African lion expert and professor at Virgina Polytechnic Institute in Blacksburg.

As for the mating, "I’ve never seen male-to-male interaction like that, and I’ve been working [in Botswana] for 20 years," she says. "I would say it's more likely a maned lioness." (See more lion pictures.)

The maned lionesses of Botswana may carry a genetic disposition toward the phenomenon, according to Luke Hunter, president of the big-cat conservation group Panthera.

View Images Maned lionesses are seen regularly in parts of northern Botswana. Photograph by Nicole Cambre, REX, Shutterstock

Such maned females may be a sign of developmental disruption either at conception or while in the womb, he said in a previous interview.

“If the former case, the genetic contribution of the sperm—which determines the sex of the fetus in most mammals—was probably aberrant, giving rise to a female with some male characteristics.

“Alternatively and perhaps more likely, the problem may have occurred during gestation if the fetus was exposed to increased levels of androgens—male hormones such as testosterone.”

If a lion mother had abnormally high androgens during pregnancy, her female offspring may end up “masculinized”—a situation that occurs occasionally in people but which is rarely observed in wild animals.

Alexander adds that other African species have evolved mascunlinized females as part of a survival strategy.

View Images It's possible the bottom lion may be a maned lioness, which likely carry a genetic disposition toward the phenomenon. Photograph by Nicole Cambre, REX, Shutterstock