BBC: Gender IQ study/if true how did difference evolve?

[Martin]

this week the BBC reported a controversial IQ gender study to be published in the British Journal of Psychology

 

http://news.bbc.co.uk/1/hi/education/4183166.stm

 

I do not take any position as to the truth, falsity, or significance of the results reported, which indicate a difference in statistical IQ spread that is related to gender----a difference in the statistical distribution

 

the comments on this BBC article are themselves interesting: it could be, as one person commented, that there are more men who are exceptionally stupid (as well as exceptionally intelligent as measured by the test used) so that on average it all balances out. (my personal view on that is who cares? we shouldnt be arguing this group average better than that group average. I am not an average and neither are you. what interests me is the spread and the exceptional cases)

 

it could be that the spread has to do entirely with differences in educational opportunity and social conditioning

 

it could be that the spread (if it exists and is not simply an artifact of poor research) has a genetic component.

 

if that is the case then one might ask how such a situation could have evolved?

 

it could be the ACCIDENTAL COLLATERAL EFFECT OF evolutionary pressure in an entirely different direction

 

it could be a SEXUAL SELECTION EFFECT like the peacock's tail, which raises chicken/egg problems. if males display intelligence-related accomplishments to attract females, why would females be attracted to this in the first place. What good is a large fancy tail on a peacock in the first place? Once the selection effect gets started then it is easy to think of reasons it would continue.

 

if it is a SURVIVAL effect, and assuming there is a genetic component, then why would there be any gender difference? if IQ-type intelligence is helpful to survival and reproductive success then it would seem apt to be just as helpful to females and to males. everybody should benefit from knowing how to catch fish and hide from the tiger.

 

well, I am not particularly well-prepared to discuss this kind of thing----but Mokele and Skye are. So I will put it out in case anybody wants to discuss it.

 

I started a news item on this too. since it is so hot-controversial.

[Ophiolite]

Some random thoughts:

1. It has always puzzled me that while we are quite ready to accept that Johnny may be smarter than Kevin, or Alice be smarter than Jane, we bridle if it is suggested that a particular group (sorted by 'race', sex or any other criteria) may be smarter than any other. A clear case of political correctness entering the scientific arena.

2. I was mildly surprised to find it was 'males' who came out as being slightly smarter than women. I expected the reverse.

3. As to the gender difference there will be a strong selection of females for child bearing characteristics. IQ becomes not irrelevant, but decidedly secondary. The full story will likely be more complex, but I don't find it surprising.

4. Finally, I would also not be at all surprised if further studies reversed these conclusions. This study is only important because of the rather unscientific reactions it is likely to generate. (Several of which may well be found in subsequent posts.)

[JustStuit]

Although the study used a large group of people I also wouldn't be surprised if another study came out the other way. I have heard the iq system is old and not 100% accurate. What's your opinion's on this.

[Martin]

... (Several of which may well be found in subsequent posts.)

 

yes! the subsequent posts have a wealth of different reactions. some I found quite sensible, like yours that further studies could well reverse the finding!

 

a lot of IFS

but if the test measures anything and if it has a genetic component then to me it would seem like a real evolutionary puzzle as to how that wider spread could have evolved

 

collateral evolution with some other selected trait is a possibility but I cannot imagine anything that would be associated with variability or spread.

Maybe mokele or skye can sort this out.

could it be that men are attracted to sameness or homogeneity in women and women attention is caught by the guy being different

could there be sexual selection for diversity

 

sorry if vague

 

have to go no time to finish idea

[LucidDreamer]

I think the exceptionally stupid men come from:

1) More mental retardation and disorders, resulting from having an XY chromosome pair instead of an XX.

2) Men who are not especially bright to begin with won't try as hard to overcome their mental difficulties, but instead will use their physicality to fulfill their needs.

 

The exceptionally bright men come from society’s pressure and men's natural inclination to try to prove themselves. If you are a man and you want to prove your worth, you better have/make money or be especially bright.

[JustStuit]

I think XY chromosone pair is normal and XX means you are female. Disorders may come from XXY and XYY i think. Is this right. I also agree that some men don't care and would not have wanted to try hard is they did not think they were smart. Many men are ignorant it seems like. I like this forum because you guyz are all smart and we don't have to deal with much of the stupidity and ignorance problems.

[LucidDreamer]

I think XY chromosone pair is normal and XX means you are female. Disorders may come from XXY and XYY i think. Is this right. I also agree that some men don't care and would not have wanted to try hard is they did not think they were smart. Many men are ignorant it seems like. I like this forum because you guyz are all smart and we don't have to deal with much of the stupidity and ignorance problems.

There are more disorders associated with XY than XX because XX has gene redundancy.

[Skye]

if that is the case then one might ask how such a situation could have evolved?

One thing it could be, to add to your list, is that because men could have more children than women, then positive traits will be given greater reward. A really successful man could have many more children than a really successful woman. This assumes a certain amount of choice in partners.

 

The interesting thing is that it mightn't be a matter of men being intrinsically smarter but of women providing greater care to their sons. This isn't too far fetched as it normally takes more effort anyway, men take longer to reach maturity and are bigger.

It has always puzzled me that while we are quite ready to accept that Johnny may be smarter than Kevin, or Alice be smarter than Jane, we bridle if it is suggested that a particular group (sorted by 'race', sex or any other criteria) may be smarter than any other. A clear case of political correctness entering the scientific arena.

I think it is because it can potentially lead to wrongful prejudice.

[shenzhou]

There are more disorders associated with XY than XX because XX has gene redundancy.

 

There is also a disproportinately large number of genes on the X chromsome that affect mental function. The X chromsome makes up about 3.7% of the genome but 27% of genetic diseases with mental retardation are X liked:

 

see this paper: X-linked genes and mental functioning. David H. Skuse. Human Molecular Genetics, 2005, Vol. 14, Review Issue 1

 

"Why should there be such a concentration

on this particular chromosome (1)? Zechner et al. (2) suggest

that the X-chromosome has been engaged in the development

of sexually selected characteristics for at least 300 million

years and that natural selection has favoured the development

of X-linked genes that are associated with higher cognitive

abilities. In particular, males are more likely than females to

be influenced by haplotypes that are associated with exceptionally

high abilities. For an equivalent reason, they are

also more likely to show deficits in mental abilities than

females because of the impact of deleterious mutations

carried in haploid state. The hypothesis offers an explanation

for the higher male variance in many aspects of cognitive

performance"

[Martin]

There is also a disproportinately large number of genes on the X chromsome that affect mental function. The X chromsome makes up about 3.7% of the genome but 27% of genetic diseases with mental retardation are X liked:

 

see this paper: X-linked genes and mental functioning. David H. Skuse. Human Molecular Genetics' date=' 2005, Vol. 14, Review Issue 1

 

"Why should there be such a concentration

on this particular chromosome (1)? Zechner et al. (2) suggest

that the X-chromosome has been engaged in the development

of sexually selected characteristics for at least 300 million

years and that natural selection has favoured the development

of X-linked genes that are associated with higher cognitive

abilities. In particular, males are more likely than females to

be influenced by haplotypes that are associated with exceptionally

high abilities. For an equivalent reason, they are

also more likely to show deficits in mental abilities than

females because of the impact of deleterious mutations

carried in haploid state. The hypothesis offers an explanation

for the higher male variance in many aspects of cognitive

performance"[/quote']

 

excuse me if I sound too enthusiastic

I think there is a brilliant chain of reasoning here, presented barebones

 

sex-selected characteristics would tend to code on the X and Y chromosomes

 

but in the man, whatever codes on either X or Y is going to likely be more variable because of less redundancy----you dont get a backup of either the X or the Y

 

so it makes sense.

 

as everybody knows I am obsessed with peacock tails, so let's apply what Shen says to that example.

Are male birds XY just like us male mammals?

 

If so then I would expect the fancy tail characteristics are somewhere on the Y chromo.

 

If so then there is less redundancy of the information because he only has ONE Y chromo.

 

If so then he should experience more variability of the fancy tail characteristics.

 

Please explain if I've made a mistake or it doesnt work this way for some reason.

 

Shen Zhou and others (skye, lucid) very interesting thanks, please explain more if you have time

[Skye]

Are male birds XY just like us male mammals?

No, birds are the opposite to us, ZZ is male, ZY is female.

[shenzhou]

as everybody knows I am obsessed with peacock tails' date=' so let's apply what Shen says to that example.

Are male birds XY just like us male mammals?

[/quote']

 

As Skye said female birds are ZW and male birds ZZ, but there is an interesting article which suggests that the sex chromsome system of birds is more likely to result in extreme sexually selected features:

 

Genetic biases for showy males: Are some genetic systems especially conducive to sexual selection

 

"Male secondary sexual characters (conspicuous ornaments, signals, colors) are among nature's most striking features. Yet, it is unclear why certain groups of organisms are more likely than others to evolve these traits. One explanation for such taxonomic biases is that some genetic systems may be especially conducive to sexual selection. Here, we present theory and simulation results demonstrating that rare alleles encoding either male ornaments or female preferences for those ornaments are better protected against random loss in species with ZZ/ZW or ZZ/ZO sex chromosome systems (male homogamety) than in species with XX/XY or XX/XO systems (male heterogamety). Moreover, this protection is much stronger in diploid than haplodiploid species. We also present empirical data showing that male secondary sexual characters are better developed in diploid than haplodiploid species and in diploid species with male homogamety than in those with male heterogamety. Thus, taxonomic biases for showy males may stem from differences in sex chromosome systems."

 

http://www.pnas.org/cgi/reprint/100/3/1089.pdf

 

and SEXUAL SELECTION AND SEX LINKAGE: http://evol.allenpress.com/evolonline/?request=get-document&issn=0014-3820&volume=058&issue=04&page=0683

 

There is another interesting example of sex specific traits in birds this time females. In cuckoos there are several host races (gentes) that only parasitise a particular species. These host races have traits such as egg size and colour that are specific to their host. Male cuckoos can mate with females from any host race but the daughters will inherit their mother's host preference.

[Martin]

As Skye said female birds are ZW and male birds ZZ' date=' but there is an interesting article which suggests that the sex chromsome system of birds is more likely to result in extreme sexually selected features:

 

...[/quote']

 

but perhaps, with birds, not so much VARIATION in sexually selected male characteristics (because they might be on a chromo that is duplicated)?

 

so male peacocks all have pretty much identical fine show-off tail

 

but whatever attentiongetting talents and distinctive abilities poor human males have are highly variable

 

that is, we can't all play the piano

we dont all tell jokes equally well

 

but male robins are much more uniformly able to sing the robin song

and so on

 

this is really interesting, wish I had more background in it

[Kedas]

If the male IQ is more spread out than women then you can also say that for every 'stupid women' there are 5 even 'stupider man'.

Basically what it means is that nature experiments more with man and chooses more for the safe solution if it comes to a women.

 

And since the very stupid man die you get the impression that the average is higher for man.