A news story at Science about a new study, which is summarised adequately in the title:
Bisexual behavior genetically tied to risk-taking, controversial DNA analysis finds
Study also finds different genes drive bisexuality versus other same-sex sexual behavior, but scientists split over data and potential for stigma
The first couple of paragraphs:
Politically and ethically fraught, research into what leads to bisexual behavior or exclusive homosexuality typically sparks controversy. The latest study, published today in Science Advances, is no exception. By mining a DNA database of some 450,000 people in the United Kingdom, a research team has concluded that the genes underlying bisexual behavior are distinct from those driving exclusive same-sex behavior, and may be intertwined with a propensity for taking risks. This connection to risk-taking, the authors suggest, may also explain why men with a history of bisexual behavior still have a reasonably high number of offspring, albeit fewer than heterosexual men, possibly explaining why the genes driving such sexual behavior have persisted.
The work has drawn a mix of strong reactions. Some scientists called the findings valuable, whereas others found fault with the underlying data. Still others argued the research could potentially stigmatize sexual minorities. The result that bisexuality is tied with risky behavior, some scientists say, could be used by others to discriminate against, and further perpetuate false narratives about, bisexual people.
I would have thought that part of the problem may be the way "risky behaviour" is used. Here further down there is a line:
These DNA patterns were linked to taking risks in life and being open to new experiences.
Well, seems almost a given that you could describe a key aspect of bisexuality as "being open to new experiences". If that was the extent of the DNA influence, it would surely count as "unsurprising".
There are some other parts of the article which are of interest, though:
From one stark evolutionary perspective, sex without the prospect of producing children could be seen as waste of time and energy—behavior that might be selected against. Yet population surveys have consistently found that about 2% to 10% of people engage in sex with others of the same sex. Studies of twins have suggested such sexual activity is at least partly heritable, and therefore has a genetic component. And scientists have proposed several evolutionary theories explaining why same-sex sexual behavior may persist.
In 2019, a research team used data from the UK Biobank, a large genetic and health database of half a million people of European ancestry in the United Kingdom, combined with data from the consumer DNA testing service 23andMe to pinpoint gene variants linked to sexual behavior. In what is still the largest genome-wide association study (GWAS) on this topic, the researchers found that having certain genetic variants could explain up to 25% of same-sex sexual behavior.
The 25% figure sounds surprisingly low? I suppose the issue of exposure to hormones in utero could take up a lot of the slack?
Anyway, the article notes that there is a lot of criticism of the study, and yeah, that issue of the use of the term "risk taking" is one of them:
Steven Reilly, a geneticist at Yale School of Medicine, and others note the use of the UK Biobank’s data itself is problematic. Most of the people in it are more than 50 years old and grew up during a time when same-sex sexual encounters were illegal in the U.K. and homosexuality was considered by many a mental disorder. That history of stigma could have affected how they responded to questions about their sexual history, he notes. He adds that because the risk-taking behavior trait used in the study comes from the answer to a single question, it’s not clear, scientifically, what “risk-taking” entails.
So, overall, sounds more than a tad dubious, but it is interesting if it does provide reason to definitely accept bisexuality as a "genuine" thing. They have complained forever that both straight and gay people get up their nose (not literally!) when they label them as just "gay in denial". And this is blackly funny:
Important formative work has been conducted that aims to understand the concept of bisexuality in the consciousness of the general population. One study, using a feeling thermometer technique, found that bisexual men and women were viewed less favorably than all other comparison populations provided (including religious, racial, political and sexuality groups), save for injection drug users.31I've always found this modern "disbelief" in bisexuality hard to understand - I would have thought that the ancient world of Greece and Rome, not to mention China and Japan, and various other societies at various stages of history, (not to mention more modern high profile individuals like Oscar Wilde), provide plenty of evidence that some men, in particular, were open to sexual activity with both genders, and didn't get hung up on categorising their behaviour.
The 25% figure sounds surprisingly low? I suppose the issue of exposure to hormones in utero could take up a lot of the slack?
ReplyDeleteNot just hormones, also chemicals that mimic hormones. The exposure probably has to be in utero and\or early years exposure, possibly through the mother during pregnancy. There is abundant literature on this. I read about that possibility over 20 years ago. It was found that in animal studies the concentrations of endocrine disruptors causing sexual maturation quirks was at the same level then found in humans. A very recent study found 95% of humans have these chemicals.
https://www.abc.net.au/news/2023-12-30/tas-how-to-reduce-exposure-to-endocrine-disrupting-chemicals/103256060
All behavior is to some extent mediated by genes. The 25% does seem low but GWAS studies are rather broad. We need something much more specific, like SOX 9 interference.
The increased openness is interesting because it is a key feature in the OCEAN personality profile and higher Openness scores are typically regarded as a good attribute.
I forgot. A recent study found that men who carry bisexual genes have more children than the rest! That perhaps solves the evolutionary conundrum of why differing sexuality persists.
ReplyDeleteYou're right Steve, it has always been there and refusal to acknowledge that has more to do politics and religion than reality. I think social media and the ubiquitous use of cell phones has bumped up the trend. That's the remarkable thing about human beings, at present our behavior can't be reduced to molecules and I suspect that will never be possible. As such I still have a faint, dim hope, to steal the words of Manning Clark, that we may still exist after our bodies have turned to dust.