Animal behaviorists have long been fascinated by occurrences of same-sex behavior in various animal species, especially when that behavior doesn't appear to be "adaptive," begging the question: If the reason why animals have sex in the wild is to produce offspring, why do some species engage in same-sex behavior?

Researchers have attempted to answer to this question for a number of species, with the most recent insights coming from a study on the sexy behaviors of a group of tortoises living on a small island in the middle of a Macedonian lake.

Golem Grad Island is not only home to a bevy of ancient Roman ruins, but also a staggeringly large population of nearly all-male tortoises. Scientists aren't exactly sure why the population is almost completely male, but suggest that there might be “a scarcity of potential nest sites that provide daughter-producing temperatures.”

Regardless, the males live in harmony with one another, with one group inhabiting the island's plateau (where the population is 95% male) and the other group inhabiting the Island's shore (where the population is 77% male). Scientists studied the two groups to see if the demographics of the respective populations would influence same-sex behavior and if this behavior would occur in the same frequency across the two groups.

What researchers discovered was that though same-sex behavior definitely occurred in both groups, nearly 74% of all recorded sex interactions among the plateau group were same-sex while just barely 30% could be said for the group along the shore. Scientists also noted some fairly odd sexual behavior, with some tortoises "observed mounting juveniles, dead males, and tortoise skeletons (empty shells of males),” while others “were seen attempting to copulate with stones that vaguely resembled a tortoise.”

So what exactly does this all mean? From an evolutionary perspective, it's useful for a sexually-aroused male tortoise to try and copulate with anything that even vaguely resembles a female tortoise, with the hopes that the resulting interaction will lead to her laying eggs.

However, due to a historical dearth of female tortoises on the island, researchers believe the males have somehow evolved mechanisms that prevent them from wholly discerning between male and female partners when engaging in sex, which permits the male tortoises to gleefully get their grooves on with one another.