Tuesday, February 20, 2018

On sexual orientation


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Part 2

Vertebrate animals such as fish, amphibians, reptiles, birds and mammals have all evolved diverse reproductive strategies that obviously work. The general mammalian reproduction strategy is, with exceptions of some oddities such as that of two egg laying species or the marsupials that incubate young in pouches common to the group, namely internal development and suckling of young and a wide range of courtship behaviours. Most readers will surely be generally familiar with the broad general details of the physiology of human reproduction. Few however will be familiar with the parallel behavioural aspects of the reproduction especially of reptiles, birds and mammals where there are extremely complex associated behaviours that bring the separate sexes together.

Take the common garden lizard or Anolis. Some may have these small iguanids sitting on a shrub or fence nodding their heads up and down as an extended fan below their throats spreads. This is meant to impress a passing female. Take as another example our common keskidee that may be seen in urban and suburban areas from time to time sitting on electricity wires making an absolute racket alongside two or three other individuals with the noisiest ones raising a crest of brilliant yellow on its head, spreading and waving its wings. This is essentially a courtship ritual meant to attract a mate, for a time anyway. But some birds actually pair bond, or marry if you will have it, for their lives. When you see flocks of parrots on an evening going to their roosts in the trees the flocks almost always consists of closely flying pairs of birds, occasionally a threesome. Or take the common white lined tanager, or parson bird, which we see about gardens in suburbia. They travel in pairs.

Mammals may come together in different ways for differing periods of time. At one extreme some may pair off briefly in a session of sexual contact while at the other extreme a pair will bond for life. Amongst our cousins the great apes display a range of bondings. The gibbons of south east Asia for example bond for life and live together in well established territories. The orangutans on the other hand are solitary and bond transiently for mating. The gorillas exist is small family groups with a silver back male leading the group. Chimpanzees on the other hand live in much larger groups and there may be one of more dominant males. Their cousins, the smaller bonobos, are promiscuous, pairing whenever possible with any available member of troop, female or male.

But there is a phenomenon that is relatively commonly seen even sometimes in the wild, where a pair of the same sex bond for extended periods, either demonstrating typical mating behaviour or going through the mechanical movements of mating. They demonstrate behaviours that amongst human beings are collectively called homosexuality, sometimes broken down into the terms gay and lesbian. Such behaviour even today may exact from society the most severe of sanctions in religious law in many countries, and perhaps not so drastic penalties in law in secular states, largely on the grounds that it is abominable or unnatural behaviour. Perhaps therefore it might be helpful to the debate to look at the occurrence of such behaviours amongst animals, noting the anthropocentricity of the words "homo" and "sexuality".

One of the problems of determining the nature of interrelationships of animals is that if one relies entirely on captive animals in artificial surroundings, observations become naturally suspect and flavoured by captivity, which is an unnatural condition for many animals. Indeed, observed behaviours may be a product of captivity. Observing animals in the field is obviously to be preferred but this is fraught with considerable difficulties, especially the time taken and the need to make observations in such a way as not to alert or divert the attention of the observed. As with humans, animals may display heterosexual behaviour, or behaviour between the two sexes, bisexual behaviour or mating behaviours with either opposite sex, or homosexual or sexual behaviours between animals of the same sex.

Sexual behaviours in many animals, especially birds and mammals, and in many invertebrates, usually include some manner of courtship or attraction between individuals, possibly some degree of bonding for a time and sometimes a measure of parenting or caring and such can vary considerably with the different species, and tend to be more common in species that have developed some measure of social organisation.

Homosexuality in animals has been widely reported in scientific literature and pops up from time to time in science columns in quality foreign newspapers and the tabloids. The very fact that homosexuality is seen in the wild in related life forms, must inevitably lead any detached and rational mind to the conclusion that variability in sexual orientation is a natural phenomenon within a broad continuum of behaviours, as natural as a silk cotton tree shedding its seeds to the winds or a hurricane hitting land somewhere in the Caribbean, and one to be expected in human behaviour. (Continues next week)

* Julian Kenny is a biologist and natural history author. He is a

former UWI Professor of Zoology and Independent Senator.