Interesting Things

While the biological basis for homosexuality remains a mystery, a team of neurobiologists reports they may have closed in on an answer — by a nose.

The team led by University of Illinois at Chicago researcher David Featherstone has discovered that sexual orientation in fruit flies is controlled by a previously unknown regulator of synapse strength. Armed with this knowledge, the researchers found they were able to use either genetic manipulation or drugs to turn the flies’ homosexual behaviour on and off within hours.

Featherstone, associate professor of biological sciences at UIC, and his co-workers discovered a gene in fruit flies they called “genderblind,” or GB. A mutation in GB turns flies bisexual.

Featherstone found the gene interesting initially because it has the unusual ability to transport the neurotransmitter glutamate out of glial cells — cells that support and nourish nerve cells but do not fire like neurons do. Previous work from his laboratory showed that changing the amount of glutamate outside cells can change the strength of nerve cell junctions, or synapses, which play a key role in human and animal behaviour.

But the GB gene became even more interesting when post-doctoral researcher Yael Grosjean noticed that all the GB mutant male flies were courting other males.

“It was very dramatic,” said Featherstone. “The GB mutant males treated other males exactly the same way normal male flies would treat a female. They even attempted copulation.”

Other genes that alter sexual orientation have been described, but most just control whether the brain develops as genetically male or female. It’s still unknown why a male brain chooses to do male things and a female brain does female things. The discovery of GB provided an opportunity to understand why males choose to mate with females.

“Based on our previous work, we reasoned that GB mutants might show homosexual behaviour because their glutamatergic synapses were altered in some way,” said Featherstone. Specifically, the GB mutant synapses might be stronger.

“Homosexual courtship might be sort of an ‘overreaction’ to sexual stimuli,” he explained.

To test this, he and his colleagues genetically altered synapse strength independent of GB, and also fed the flies drugs that can alter synapse strength. As predicted, they were able to turn fly homosexuality on and off — and within hours.

“It was amazing. I never thought we’d be able to do that sort of thing, because sexual orientation is supposed to be hard-wired,” he said. “This fundamentally changes how we think about this behavior.”

Featherstone and his colleagues reasoned that adult fly brains have dual-track sensory circuits, one that triggers heterosexual behavior, the other homosexual. When GB suppresses glutamatergic synapses, the homosexual circuit is blocked.

Further work showed precisely how this happens — without GB to suppress synapse strength, the flies no longer interpreted smells the same way.

“Pheromones are powerful sexual stimuli,” Featherstone said. “As it turns out, the GB mutant flies were perceiving pheromones differently. Specifically, the GB mutant males were no longer recognizing male pheromones as a repulsive stimulus.”

Featherstone says it may someday be possible to domesticate insects such as fruit flies and manipulate their sense of smell to turn them into useful pollinators rather than costly pests.-Press release from Nature Neuroscience

Fascinating research that has turned up an accidental discovery that could revolutionise pest control. Spraying sexuality-switching chemicals sounds to me an incredibly bad idea, even if it only affects insects, but I have no doubt that someone will try it. I’m more interested, however, in the aspect of this that proves that, in insects at least, homosexuality can be induced and repressed. With this being proved in insects, it is probably only a matter of time before similar discoveries are made for humans, though it is likely to be a far more complex combination of genes, and that will open up a whole can of ethical worms.

There are some people who view homosexuality to be a mental disorder rather than an aspect of diversity, and seek to provide a cure. Currently there are any number of therapies on offer, some more bizarre than others. They are especially popular amongst conservative christians and similar groups. Conversion therapy, as it is called, (or sometimes reparitive therapy), is not particularly effective, with frequent psychological side-effects, and only rarely results in a permanent conversion with no relapses. In spite of their ineffectiveness, and sometimes methods that in other circumstances might be described as torture, they are overwhelmingly endorsed by the evangelical movement. Should a reliable drug be found that changes sexual inclinations, it will find eager cheerleaders, and more importantly perhaps, extremely deep pockets where funding is concerned. It is likely that such research is already underway.

There are some homosexuals who, for religious and other reasons, really do desire to be “cured”. In such cases I suppose it would be right to provide such medication, just as sex-change operations are made available. But such a medication is also another tool in the arsenal of intolerance. No longer would people be able to claim that homosexuality is not a choice. One can imagine a state such as Iran, which already claims to contain no homosexuals, making such a drug mandatory for those with tendencies deemed deviant by the state. Of course, that could never possibly happen in our enlightened western world. (Insert laughter track here.)

Where homosexuality is now grudgingly tolerated, it is easy to imagine more and more pressure, from family, church, or employers, being heaped upon individuals to get themselves “fixed”. Consider that the US army, never shy about trying out interesting new drugs upon its troops, is utterly opposed to having homosexuals within its ranks. Currently they are fired upon discovery, but a conversion drug would allow someone to keep his or her job. It’s not hard to imagine that someone might make that choice in order to keep alive their career and their tight-knit support network. Someone in that position is incredibly vulnerable to coercion from their superior officers.

I wanted to keep this blog politics free, and just about science, but sometimes science and politics get intertwined. I apologise for the intrusion, but the ethics of science are always worthy of thought. We should always consider the darker possibilities of a discovery, as well as the hopeful ones.

What do you think? Should such a drug for humans even be researched in the first place, or is it too dangerous to our liberties? Myself, I find it a pretty scary thought.