Gay or straight, it's decided at birth

« previous post | next post »

That's the head that the New Scientist chose for the print version (in the 21 June issue) of its story (by Andy Coghlan) on the Savic/Lindström studies that Mark Liberman reported on here on Language Log (with a link to the New Scientist's 16 June on-line version, which had a different head: "Gay brains structured like those of the opposite sex"). Mark noted that different publications headed their stories in different ways: as the discovery of a similarity between gay people and straight people of the opposite sex; as a discovery about homosexuals; or (mostly) as the discovery of a similarity between homosexual men and heterosexual women. Now the New Scientist has promoted the "decided at birth" or "born that way" interpretation of the experiments from the story's lead paragraph to its head.

And it featured the story in an editorial

It's a queer life

We need to ditch the idea that homosexuality is unnatural

First, the main story. The two versions begin in slightly different ways, with "biologically fixed trait" on-line and "biology rather than choice" in print, and with "aggressiveness" on-line and "aggression" in print. On-line:

Brain scans have provided the most compelling evidence yet that being gay or straight is a biologically fixed trait.

The scans reveal that in gay people, key structures of the brain governing emotion, mood, anxiety and aggressiveness resemble those in straight people of the opposite sex.

In print:

Brain scans have provided the most compelling evidence yet that being gay or straight is down to biology rather than choice.

Tantalisingly, the scans reveal that in gay people, key structures of the brain governing emotion, mood, anxiety and aggression resemble those in straight people of the opposite sex.

There were two sets of findings, one concerning asymmetry vs. symmetry of the two hemispheres of the brain and one concerning patterns of connection between the amygdalas and other parts of the brain. In each substudy, gay subjects of one sex and straight subjects of the other sex resembled each other. As Mark argued at length in his earlier posting, the straight-gay differences in the first substudy were very small (unable to support "essentialist" claims that gay and straight are categorically different), and that such differences in the second substudy couldn't be evaluated from the information in the published report (though Mark suspected that the differences there would turn out to be equally unimpressive).

In the New Scientist, these second differences were communicated by images of amygdalas, with areas said to be strongly connected to other parts of the brain indicated in red. This picture is labeled:


Brain connections from emotional centres, the amygdalas, clearly show that "gay" patterns match those in "straight" people of the opposite gender

These patterns of connectivity are described as follows:

In straight women and gay men, the signals from the amygdala ran mainly into the regions of the brain that mediate mood and anxiety [in the on-line version: "that manifest fear as intense anxiety"].

In straight men and lesbians, the amygdala fed their their signals mainly into the sensorimotor cortex and the striatum, regions of the brain that trigger "fright or flight" [a typo for "fight or flight"; this was correct on-line] in response to fear. "It's a more action-related response than in straight women," says Savic.

(Side point of interest to linguists: the occurrence of both the regular plural amygdalas and the zero plural amygdala in the article.)

First we get an (unsupportable) essentialist interpretation of the statistics, and then this feeds into some vulgar phrenology, in which the areas of the brain are seen as serving particular high-level functions: the amygdalas are the seat of emotion, other regions of the brain regulate mood and anxiety, and still others are action-oriented. What's communicated as a result reproduces folk theories of sex differences, with moody, passive, anxious women opposed to active, aggressive men. And it reproduces one folk theory of sexuality (there are several) — that gay men are feminine in nature, lesbians masculine. Indeed, it appears to support this folk theory by providing evidence that this cross-identification is anatomical, not cultural.

Not just anatomical, but probably present at birth. As Coghlan notes in the printed story:

Savic and her colleague, Per Lindström, chose to measure brain parameters that are probably [on-line:  "are likely to have been"] fixed at birth.

That is, brain parameters that probably are either genetic or determined in utero (or, of course, some of each).

Two comments here. First, I know absolutely nothing about the development of brain structures in childhood, but someone ought to be looking at these two parameters, to see if they are indeed fixed at birth and not affected by experience (or processes of maturation).

Second, I wonder about the selection of these two parameters, from among the great many aspects of brain structure that the investigators might have looked at. In particular, I wonder if they (or associates of theirs) looked at some other parameters in pilot studies but came up short, so that what we're seeing now is their two lucky shots, with everything else languishing in that famous file drawer.

In any case, the studies are now being taken as showing that sexuality is determined at birth, though this conclusion doesn't follow at all from the results. Nor do the studies shed any light on the causes of homosexuality. In fact, they make the whole topic more mysterious than ever: how could these particular very small (and non-categorical) differences in brain anatomy work themselves out as sexual desire for persons of the same sex?

(Topic for a future posting: the bewilderingly large number of ways in which people use the term gay and related terms.)

Now to the editorial, which was set off by a radio interview:

Iris Robinson held nothing back this month when interviewed on BBC radio. "Homosexuality is disgusting, nauseating, shameful, wicked and vile". Her Christian belief told her it is "an abomination" and she advised homosexuals to seek psychiatric help. Such intolerance may be bread and butter for preachers of the fire-and-brimstone variety but it is rare in UK politics. Robinson is a Member of Parliament and of the Northern Ireland Assembly.

The editorial goes on to argue that homosexuality is neither "unnatural" nor a mental disorder, concluding:

Does it matter that a high-profile politician is peddling ideas not backed by scientific or medical evidence? For one particular reason, yes. Robinson is chair of the Northern Ireland Assembly's health committee. One can't help wondering about the quality of healthcare the people of Northern Ireland can expect.




  1. Blake Stacey said,

    June 26, 2008 @ 2:44 pm


    My default hypothesis is now, "If it's a news story about the brain, it's probably deceptive."

  2. Justin said,

    June 26, 2008 @ 3:06 pm

    @Arnold Zwicky – I think that your comments are right on the mark. One of the fundamental concepts of neuroscience is that brains are a result of the interaction between biology and behavior. "Learning," as defined by neuroscientists, is behaviorally-induced changes in the biological connectivity of neurons. Therefore, it is impossible to conclude any "biologically fixed trait" based only on the observation of differences between two sets of brains scans. Even with maturation studies, it would be difficult/impossible to parse the two apart based on brain scans.

    The neophenology serves only to further highlight the author's lack of knowledge of the subject.

    @Blake Stacey – good null hypothesis :)

  3. David Eddyshaw said,

    June 26, 2008 @ 3:14 pm

    Poor old New Scientist; increasingly unworthy of its name.

    I recall a few months back an article suggesting that light might be shed on modern physics by the insights of speakers of Algonquian languages, on account of the "fact" that they make no distinction between nouns and verbs.

    Hard to know where to begin …

  4. Rubrick said,

    June 26, 2008 @ 5:09 pm

    David EddyShaw: I think any publication called New Scientist is pretty much doomed to become increasingly unworthy of its name over time, regardless of the "Scientist" part. :-)

  5. Bob Ladd said,

    June 26, 2008 @ 5:27 pm

    In partial defense (or defence) of New Scientist, I've been a subscriber for nearly 25 and their coverage of language-related stories has definitely improved over that time. That's not to say they don't screw up and/or sensationalize more than they should – their recent story on the future of English is an embarassing case in point – but only that they take language stuff more seriously than they used to, and get it right more often.

  6. Michael Garofalo said,

    June 26, 2008 @ 5:27 pm

    I keep wondering: if homosexuality is determined genetically, wouldn't it, according to the Mendelian theory of genetics, disappear after a single generation, since only heterosexual couples can reproduce? Even if we take cultural pressure into consideration, there's no way that homosexuality, being documented as early as (if not earlier than) the Old Testament references to Sodom and Gomorrah (the former being the root of "sodomy"), could have survived this long unless it's an experientially gained trait.

    My hypothesis, taking this latest study into account, is that certain genetic conditions can predispose a person to a sexual lifestyle of homosexuality (in this case, the differences that showed up on brain scans). That would explain the genetic trait surviving this long (not all who possess the predisposition will follow it) and would in fact confirm the age-old belief that homosexuality is, at least to some extent, a person's choice (as opposed to eye color, height, or other non-ambiguous heritable traits) while simultaneously confirming the sanity and decision-making ability of those who turned from gay to straight sexual orientation.

  7. Lee said,

    June 26, 2008 @ 5:45 pm

    Michael, consider the case of sterile bees in a hive. Your reasoning about genetics could not account for them.

    Interestingly there is now some reason to think that the genetic factors that dispose a man toward homosexual behavior are also responsible for increased fecundity in some of his female relatives.

    See here:
    "Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity"

    Your exact question is addressed: "The Darwinian paradox of male homosexuality in humans is examined, i.e. if male homosexuality has a genetic component and homosexuals reproduce less than heterosexuals, then why is this trait maintained in the population?"

  8. Peter said,

    June 26, 2008 @ 5:47 pm

    Michael — I think your argument confuses features of children and features of parents. Why should homosexuality disappear after one generation if it had a genetic cause? If all heterosexual couples had a fixed chance of having a homosexual child, say 5%, then this percentage would remain the same for every pair of heterosexual parents, generation after generation, even though such homosexual children themselves may have no offspring. In other words, any genetic cause for homosexuality is a property of the (presumably heterosexual) parents of homosexuals, not a property of their homosexual offspring, and this property may continue in the population for a long time (until mutations or evolutionary adaptation eliminates it).

  9. Blake Stacey said,

    June 26, 2008 @ 5:54 pm

    1. Recessive genes.

    2. Inclusive fitness.

    3. The ability to have sex with a partner capable of producing offspring even if we don't enjoy it very much.

    Developmental biology presents other possibilities.

  10. Virgil Ikari said,

    June 26, 2008 @ 6:14 pm

    In "On Human Nature," Edward O. Wilson posits that the genetic basis for homosexuality might be due to the increased genetic fitness of a family which includes a homosexual member. I understand that to be a form of inclusive fitness.

  11. Coby Lubliner said,

    June 26, 2008 @ 6:16 pm

    I thought that the "regular" plural was amygdalae.

  12. Taylor S. said,

    June 26, 2008 @ 6:28 pm

    Mendelian Genetics is a great tool for looking at how traits that are determined by ONE gene is passed down, but it is not very useful in simplifying complex geneitc traits.

    As Kenneth Weiss (2002, p. 44) has pointed out, although Mendelian genetics provides a foundation for understanding heredity, "a misleading, oversimplified, and overdeterministic view of life is one of the possible consequences."

    Homoesexuality, if genetic (as I think/know it is, being gay myself and not haven chosen to be), is most likely a Polygenic trait–meaning that many genescontribute to a single effect. As such, two heterosexual carriers can produce a homosexual baby if they carry some genes, but not all.

  13. Arnold Zwicky said,

    June 26, 2008 @ 8:11 pm

    Oh dear. I should have inserted some sort of request not to let the thread go off into a discussion of the genetic bases for homosexuality — which is just guaranteed to produce lots of heat and not a lot of light.

    If you want to talk about the topic, do it on your own blog and link to Language Log, please — as Mark asked in his instructions to commenters.

  14. Arnold Zwicky said,

    June 26, 2008 @ 8:15 pm

    On reflection, I've decided that there's no way to keep people from taking the discussion any way they want, no matter what the bloggers ask. My first idea was to delete my posting in its entirety, but now I've decided to disable comments.

    I'm deeply sorry to have introduced the topic at all.

  15. Rick S said,

    June 26, 2008 @ 8:15 pm

    @Michael Garofalo:
    1. Gregor Mendel developed his theories working with species with some very simple genetic machinery. Most visible characteristics of an organism, even of those he was working with, are nowhere near as simply related to their genes. Mendelian inheritance (not "theory of genetics"), with its simple dominant/recessive schema, is rare in the real world. If it applied to humans, we would all have either brown eyes (3/4) or blue eyes (1/4).
    2. Homosexuality is not infertility. It could well be argued that historically, social pressure upon homosexuals to lead a heterosexual lifestyle has tended to ensure the survival of whatever genetic basis homosexuality might have. (This is, to me, a most delightful irony!)

RSS feed for comments on this post