Inherent in the statement that homosexuality ‘is not natural’ are two assumptions. The first is that what is ‘natural’ is fundamentally good and moral. The second assumption is that homosexual behaviour is not seen anywhere else in the natural world – for such behaviour is assumed to be the conscious choice of sinful humans. This argument might carry some weight if there were no examples of homosexual activity and behaviour in other animals. This is not the case, however.

Bruce Bagemihl has trawled through many scientific journals, as well as respected naturalist’s notebooks, to uncover a wealth of information on homosexual behaviour within the animal kingdom.

“Homosexuality in its myriad of forms has been scientifically documented in more than 450 species of mammals, birds, reptiles, insects and other animals worldwide. It is found in every major geographic region and every major animal group. Animals engage in all types of non-reproductive sexual behaviour. Same-sex sexual expression includes courtship, pair-bonding, sex and co-parenting – even instances of lifelong homosexual bonding in species that do not have lifelong heterosexual bonding.”[1]

The examples Bagemihl cites indicate the great complexity that exists in the natural world for both gender distinctions and differences in sexual behaviour.

We might assume that animals are either male or female, however some animals undergo a natural gender change during the course of their life. This phenomenon is found in invertebrates such as oysters which may undergo a complete sex reversal during their lives (sometimes more than once). Coral reef fish also provide examples. Over 50 species of such fish have been found to be transsexual. Working ovaries become working testes, and a fish that was once female is able to mate as a male.[2]

These gender complexities continue with gynandromorphic specimens. A gynandromorph is an animal that appears divided in half, one side male in appearance and the other female. There is usually a clear dividing line between the two halves. An example of a gynandromorphic butterfly is shown in the picture on the right and clearly shows the male/female difference from side to side.

One spider gynandromorph was observed to court and mate with females using its male organs, but also to build an egg case (which is typical female behaviour).[3]

Scientific American reported the case of a zebra finch that was gynandromorphic. The right side displayed the male red feathers around the eye and zebra striping, while the other side looked female. The bird had both male and female gonads, yet it acted male. The scientists found that one side of the brain was genetically male and the other side female.[4]

Turning to same-sex behaviour, the case of male Black Swans is worth telling in detail. Some male Black Swans “form stable, long lasting homosexual pairs. Like heterosexual mates, same-sex partners often remain together for many years.”[5]

These male partners have far more success in defending their territory (by pooling their strength), so same-sex partners often gain the best spots on the lake with far larger territories. Partially because of this, but also because of more evenly shared incubation duties, same-sex partners are more successful parents. They incubate eggs that have been abandoned or taken by stealth, as well as eggs resulting from a temporary ‘fling’ with a female swan. Same-sex partners have an 80% success rate in raising their chicks, whereas heterosexual Black Swan partners average 30%.[6] The success rate is measured as the proportion of chicks that survive.

In the study population, 25% of successful Black Swan parents were homosexual pairs, despite the fact that the group of homosexual pairs made up only 13% of the total number of associations or breeding pairs.[7]

While it would be inappropriate to suggest that because it happens in the animal world, then it is fine for humans (for instance, many species are not monogamous and some notoriously practise cannibalism after sex!), this information about homosexuality in the animal kingdom is helpful:

• It tells us that homosexual behaviour has been documented in many different species throughout the natural world.
• It tells us that the belief that all life consists of two absolutely distinct sexes, male and female, is a simplification of what is actually the case in nature.
• It tells us that an assumption that homosexuality is not found in nature, and thus is unnatural, is not valid.
• It tells us that any theological position that depends upon this assumption is questionable.