Sheep get a bad rap. Not only are they commonly portrayed in children’s stories as the helpless masses preyed upon by some evil predators, among adults, “sheep” has long been a byword for gullible, simple-minded conformism. To be a “sheep” is to be someone who just goes with the herd and never has an independent thought. But when it comes to sexual behavior, sheep are no sheep. In fact, they display some of the most varied sexual diversity in the animal kingdom.
Going back to at least the early 1970s, when the Canadian biologist Valerius Geist observed that some male sheep, known as rams, mounted other sheep “irrespective of the latter’s sex”, researchers have been aware that sheep grazed on both sides of the fence. In the decades since, scientists have paid particular attention to sheep, and as a result, sheep sexual behavior is among the best understood and measured of any species. As a 2009 study in the Journal of Neuroendocrinology sums up the research:
By far the largest group of rams is female-oriented (∼60%), while ∼8–10% are male-oriented, ∼12–18% are asexual, and ∼18–22% are bisexual.
What makes these findings so remarkable isn’t their bisexuality — we see that everywhere in nature. Nor the fact that apparently asexual rams exist, which is rare (though not unheard of) among sexually reproducing animals. What stands out is that 8–10% are exclusively homosexual (“male-oriented”). This makes sheep the only documented species outside of humans to exhibit homosexuality. For comparison, 1,500 species have been observed engaging in bi behavior.
Researchers have also extensively studied sheep’s natal and behavioral development to better understand why some sheep are oriented toward same-sex behavior while others are not. What they’ve found are hormonal and neurological differences tracing back to the earliest stages of development. Gay or bi sheep have different brain structures. Scientists have long hypothesized why some animals engage in same-sex behavior. Is it an expression of dominance? Socio-sexual bonding? Lack of access to opposite-sex partners? In the case of sheep, the answer is more conclusive: gay or bi sheep appear to be literally “born this way”. The title of a 2020 study says it all: “Programmed for Preference: The Biology of Same-Sex Attraction in Rams.”
Going back to 2004, Charles E. Roselli, Ph.D., who has led many of the studies on sheep sexual behavior over the past 30 years, said that sheep research “strongly suggests that sexual preference is biologically determined in animals”.
Not everyone agrees. A 2019 article in The Independent interviewed a commercial sheep breeder along with the chief executive of the National Sheep Association. The executive called the notion of gay or bi sheep “nonsense”, acknowledging that “you get females riding each other and you’ll get males riding each other”, but chalking it up to overactive sex drives and not any kind of orientation or sexual preference. For his part, the commercial breeder simply said that the amount of same-sex behavior is a big problem in his line of work. Even critics cannot deny the things they witness, only what they choose to call them.
The long and short of it is that sheep are the only creatures aside from humans who display such a broad range of sexual behaviors. Storytellers have pulled the wool over our eyes, but shorn of our preconceived notions, sheep aren’t very “sheep-like” at all. Of all the animals science has studied, they are, in some ways, the closest to us.