Tuesday, June 24, 2008 | Reason : In the News | print version

Evolutionarily Preserved Signature Found In The Primate Brain

by Science Daily

Thanks to GP for the link.

http://www.sciencedaily.com/releases/2008/06/080619203301.htm

Evolutionarily Preserved Signature Found In The Primate Brain

ScienceDaily (June 24, 2008) — Researchers have determined that there are hundreds of biological differences between the sexes when it comes to gene expression in the cerebral cortex of humans and other primates. These findings indicate that some of these differences arose a very long time ago and have been preserved through evolution.

These conserved differences constitute a signature of sex differences in the brain.

Many more obvious gender differences have been preserved throughout primate evolution; examples include average body size and weight, and genitalia design. This study, believed to be the first of its kind, focuses on gene expression within the cerebral cortex. The cerebral cortex is involved in many of the more complex functions in both humans and other primates, including memory, attentiveness, thought processes and language.

The researchers measured gene expression in the brains of male and female primates from three species: humans, macaques, and marmosets. To measure activity of specific genes, the products of genes (RNA) obtained from the brain of each animal were hybridized to microarrays containing thousands of DNA clones coding for thousands of genes. The authors also investigated DNA sequence differences among primates for genes showing different levels of expression between the sexes.

"Knowledge about gender differences is important for many reasons. For example, this information may be used in the future to calculate medical dosages, as well as for other treatments of diseases or damage to the brain," says team leader Professor Elena Jazin, at Uppsala University, Sweden.

In addition to the results mentioned above, the researchers also report on evolutionary speeds in genes that have been identified as male or female-oriented. This could provide clues about the power of natural selection processes during the evolution of primates.

Lead author Björn Reinius notes that the study does not determine whether these differences in gene expression are in any way functionally significant. Such questions remain to be answered by future studies.

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1. Comment #198547 by MikedubB on June 24, 2008 at 8:40 am

Maybe one day, with the help of genetics, we can finally find a cure for that 'deadliest of diseases', Homosexuality. bum,bum,bum!! (dramatic music)
Wow, I was meaning this to be a bit of a joke, but I am kinda surprised I even said it. Really, is that kinda implied here? even though it is not stating a 'functional significance'.
(this could get pretty heated)

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2. Comment #198549 by MikedubB on June 24, 2008 at 8:42 am

To be clear, I wouldn't want a genetecist changing the way I think and feel. So I presume others would not either, but I could be wrong.

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3. Comment #198551 by zeroangel on June 24, 2008 at 8:43 am

I have long maintained, at the risk of being called a sexist, that there are general, fundamental differences between the way men and women think / the way they approach problems or conflict.

It would seem that my POV is vindicated.

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4. Comment #198554 by mordacious1 on June 24, 2008 at 8:45 am

MikedubB

Huh?

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5. Comment #198562 by MikedubB on June 24, 2008 at 8:59 am

We have all seen the studies released that clarify a genetic difference between sexes and heteros and homos, so I think it is just a matter of time until you have a wacky geneticist out there claiming he can 'fix' the 'problem' and put you 'right in the eyes of the Lord forever more' I can hear em now. It is a scary thought, but definitely plausible. Research like this has implications that go far beyond the pale when expounded by radicals. Thats what I meant.

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6. Comment #198587 by clatz on June 24, 2008 at 9:20 am

Here is the link to the paper itself:
http://www.plosgenetics.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pgen.1000100

The discussion section is pretty good.

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7. Comment #198589 by TeraBrat on June 24, 2008 at 9:24 am

Homosexuality is natural occurence. It occurs in the animal kingdom and there's nothing to "fix". In fact I think it's a good thing. There's a reason for it or it wouldn't exist.

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8. Comment #198591 by Count von Count on June 24, 2008 at 9:25 am

Comment #198562 by MikedubB -
Of course it is a problem when radicals try to impose crazy ideas on others, but it sounds like you are claiming that therefore geneticists should not study differences in brains as expressed by DNA. Scare-mongering about science is exactly the kind of thing that radical religious people do (and are quite good at). A rational approach is much more preferable.

Maybe I am misinterpreting your statement, but what you said makes it sound like you have been reading a bit too much science fiction (which is pretty good at scare-mongering itself, e.g. Brave New World).

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9. Comment #198592 by Spinoza on June 24, 2008 at 9:25 am

TeraBrat, even if it WEREN'T a natural occurrence that occurs in the animal kingdom... so what?

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10. Comment #198605 by JLD Calgary on June 24, 2008 at 9:47 am

The big question is whether it the homosexuality genes would be turned off in the future by parents when the technology makes it easy to have designer babies who want their kids to have the "normal life" (or at least fit in the norm).

They already do this with some congenital defects and such. It's not a far stretch. Depends on which Christians (and others) get over first, homophobia or gene manipulation.

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11. Comment #198610 by MikedubB on June 24, 2008 at 9:56 am

JLD hit it on the head. I love the research but it allows for some interesting 'moral quandaries'.

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12. Comment #198615 by Sciros on June 24, 2008 at 10:03 am

Spinoza: then homophobes would have an easier time convincing each other that homosexuality is a conscious choice. That "it occurs in other animal species" has always been a useful argument against the notion.

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13. Comment #198621 by ThoughtsonCommonToad on June 24, 2008 at 10:10 am

TeraBrat

There's a reason for it or it wouldn't exist.

What are you talking about? Can you clarify. To talk of reasons seems strange in this context.

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14. Comment #198630 by Epinephrine on June 24, 2008 at 10:19 am

Homosexuality is natural occurence.

Agreed.

It occurs in the animal kingdom

and there's nothing to "fix".

In fact I think it's a good thing.

Opinion, but agreed.

If by reason, you mean advantage, I will disagree and call this a fallacy.

Many evolutionarily preserved changes exist without providing an advantage - is the human inability to synthesise Vitamin C a good thing?

Is it a good thing that the recurrent laryngeal nerve loops around the aorta? (I love that example, and I learned it here!)

No, these are things that could easily be improved on. Humans would be better off with the abiliy to synthesise their own vitamin C, as we are no longer fruit-eating tree dwellers, and the laryngeal nerve would be much better off enervating the larynx directly, rather than taking a detour to the chest. Blind cave fish would likely be fine if they had kept their eyes, and the human retina would likely function better if the blood vessels were behind the receptors.

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15. Comment #198636 by hungarianelephant on June 24, 2008 at 10:29 am

TeraBrat, even if [homosexuality] WEREN'T a natural occurrence that occurs in the animal kingdom... so what?

You can also turn that question around.

Even if it is a natural occurrence, what justification is there to prevent parents from selecting against it (if they can: it's far from certain that it is solely genetic)?

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16. Comment #198641 by spoo on June 24, 2008 at 10:39 am

I guess if you wanted to make a long shot, you could argue that homosexuality among certain individuals may enhance other individuals' chance of reproduction.

Or, it might in a general sense provide a more stable/secure environment in some odd ways that is positive for the collective set of genes in society. I have no idea. Just thoughts.

However, that sort of sounds like martyrdom genes, or goes into "group selection" territory.

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17. Comment #198647 by Sargeist on June 24, 2008 at 10:46 am

I tend to be of the opinion that it's the old genie out of the bottle thing as regards genetic manipulation. If it's possible, someone somewhere will do it, and we'll eventually end up in a Gattaca-like situation. But, you know, things change, opinions change, and weird things eventually become normal.

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18. Comment #198788 by andrewtott on June 24, 2008 at 1:31 pm

If homosexuality harms no one - who cares!

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19. Comment #198878 by Neal on June 24, 2008 at 3:38 pm

From Comment #198589 by TeraBrat on June 24, 2008 at 9:24 am

"Homosexuality is natural occurence. It occurs in the animal kingdom and there's nothing to "fix". In fact I think it's a good thing. There's a reason for it or it wouldn't exist."

Is it possible that homosexuality is caused by a mis-firing of some other evolutionary trait?

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20. Comment #198904 by robotaholic on June 24, 2008 at 5:14 pm

I'm gay and if you saw me you'd think homosexuality is a good thing!

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21. Comment #198910 by AoClay on June 24, 2008 at 5:40 pm

Sciros,
The point is so what even if it was a choice? I've never understood how whether or not it's a choice means anything other than a good (or formerly-good) scientific question.

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22. Comment #199095 by Faithhead on June 25, 2008 at 7:21 am

We have all seen the studies released that clarify a genetic difference between sexes and heteros and homos, so I think it is just a matter of time until you have a wacky geneticist out there claiming he can 'fix' the 'problem' and put you 'right in the eyes of the Lord forever more' I can hear em now. It is a scary thought, but definitely plausible. Research like this has implications that go far beyond the pale when expounded by radicals. Thats what I meant

Its sad we must consider the implications of genetic research like this. I wont be as bold as saying we should disregard the religious take on this(because unfortunately I can hear the fundy responce too)but I applaud the research and would definately be interested in reading the findings when they are published.

I guess if you wanted to make a long shot, you could argue that homosexuality among certain individuals may enhance other individuals' chance of reproduction.

Or, it might in a general sense provide a more stable/secure environment in some odd ways that is positive for the collective set of genes in society. I have no idea. Just thoughts.

However, that sort of sounds like martyrdom genes, or goes into "group selection" territory.

I would not really be inclined to think in these terms. If homosexuality had any genetic link, regardless of the alturistic benifits it would be too severely selected against by selection pressures to survive.

Is it possible that homosexuality is caused by a mis-firing of some other evolutionary trait?

More likely. Not that this carries any negative connoctations as some religious folk would like to infer.

If homosexuality harms no one - who cares!

Seconded

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23. Comment #199131 by Darwin's badger on June 25, 2008 at 8:13 am

Comment #198589 by TeraBrat on June 24, 2008 at 9:24 am
Homosexuality is natural occurence. It occurs in the animal kingdom and there's nothing to "fix". In fact I think it's a good thing. There's a reason for it or it wouldn't exist.

Not a comment upon homosexuality, but a comment upon this argument: Do you feel the same about cancer, which is also a natural occurrence in the animal and plant kingdom?

It's a sloppy argument, in the same way that some people argue that herbal remedies must be safer than manufactured drugs because they're 'natural'. They've obviously never heard of atropa belladonna or amanita phalloides.

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24. Comment #199201 by spoo on June 25, 2008 at 10:13 am

If homosexuality had any genetic link, regardless of the alturistic benifits it would be too severely selected against by selection pressures to survive.

I didn't really consider this side of it - thanks for the input.

But are you saying something else than genes would explain it?

I find it hard to explain why genes that ultimately lead to their own end of line would survive...

It could of course be an effect or byproduct of a shared gene/set of genes that is/are also responsible for other generic human traits, that are so important that it/they survive by means of selection. Maybe even, and a horrible analogy here; some kind of "parasitic gene"?

Another possibility could be an extraordinary high chance for mutations in this part of the genome, causing this trait to resurface even after selection did it's work.

Clearly, there are also "shades of gray" between heterosexuality and homosexuality -- bisexuality. Maybe we're just all bisexual to varying degrees, heterosexuality and homosexuality just representing the extremes of the scale?

Since heterosexuality seems to be the more common one, and the one with the best chance of reproduction, maybe it's a case of some dominant/recessive-y business going on here.

Or is the assumption that the "gay gene" wouldn't survive once you let selection play out it's role a false one? Maybe evolution just has been busy sorting out other, more noisy parts of the genome, and will get there eventually...?

These are merely thoughts and questions.. Feel free to dismiss or shoot them down :)

All of this aside, I'm also in the "if it harms no one, who cares" club. The problem here, of course, is people's varying interpretation of "harm"... :P

I don't see homosexuals as the cause for hurricanes, earthquakes, drought etc, like certain other groups believe.

Neither do I see them trying to restrict how I live my life and what I can do, based on old fairy tales, like certain other people try to.

Neither do I see them trying to limit what type of potentially revolutionary science and research can be done, based on the belief that cells have "souls", like certain other people try to.

There's the occasional annoyingly socialistic and political correctness noise coming from the movement, but I guess we'll have to tolerate some amount of that if the end result is less discrimination based on nonsense.

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25. Comment #199216 by Border Collie on June 25, 2008 at 10:37 am

Wow, differences in male and female primate brains. Amazing.

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26. Comment #199221 by KRKBAB on June 25, 2008 at 10:46 am

Dawkins is saying there should no longer be a taboo against criticizing religion. Why not homosexuality? We TOO OFTEN have to dance around any discussion about homosexuality. I accept it. I have zero prblem with gay people. So what? It's also "ok" to totally abstain from sex or be bisexual. If there is some scientific reasoning or a genetic explanation of why some (or even many) humans are not hetero, then let's delve into it without politically correct hesitation.

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27. Comment #199744 by T4Baxter on June 26, 2008 at 9:40 am

It seems pretty obvious that a homosexual gene won't be selected for as they tend not to reproduce so successfully, if at all. I'm aware that a large proportion go on to marry and have children as a heterosexual would (is it for the sake of having children, or do they 'change their minds'? another discussion perhaps) There was a story earlier, I believe it was on here, about similarities between the Gay male brain asymmetry and the straight female brain asymmetry which suggests it is a genuinely unavoidable trait, though, none the less, suggestive of a developmental 'screw up'. I think all parents, no matter how 'liberal', would be saddened that their offspring will not have a, comparably, normal life as, even in this day and age, they will be subjected to social pressures from classmates etc, which are not inflicted on heterosexual individuals. Kids are cruel.

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