Intelligence Gene or More Eugenics Bull Puckey?

reply to post by soficrow


Genetic analysis of IQ in young adulthood: a Russian twin study.

Abstract
The present study is an investigation of 80 like-sex, Russian twin pairs aged 16–28 years undertaken to replicate and extend the existent research literature on the heritability of cognitive ability in young adults. Up to date, no study examining cognitive abilities in Russian population adult twins has been carried out. The main objective of the present investigation is to analyze the genetic and environmental contributions to individual differences in general cognitive ability in a sample of young adult Russian twins. The Russian adaptation of the Wechsler Adult Intelligence Scale (WAIS; Wechsler, 1972) was administered separately to members of twin pairs during the single visit at their home by two testers. The model-fitting showed that a simple genetic model, including additive genetic and nonshared environmental effects, provided the adequate and most parsimonious description of verbal, performance and full-scale IQ data. Additive genetic influences accounted for approximately the same amount of variance in verbal, performance and full-scale IQ data––86%, 84% and 89%, respectively. The results are consistent with the reports from the majority of studies, suggesting an increased heritability and decreased shared environmental influences on IQ variability in adulthood compared to childhood.

reply to post by Antigod

I've never ever seen an anthropolgist deny that earlier versions of our species were less intelligent because of their overall smaller brains. You see this proudly trotted out in class, the line up of replica crania from homo habilis to modern man, and the increase in brain size with each one as proof of greater intelligence

You're quite right - one of the main tenets of human evolutionary theory is that our brains just kept getting bigger as we kept getting smarter. This dogmatic misrepresentation was achieved by absolutely ignoring the existence of Neanderthals - and thus, "overlooking" the fact that Neanderthal brains were substantially larger than those of modern humans.

With an average cranial capacity of 1600cc,[14] Neanderthal's cranial capacity is known to be notably larger than the 1400cc average for modern humans, indicating that their brain size was larger.

H. neanderthalensis also had an average brain size of 1,450 cc with a range from 1,125cc to 1,750cc. The average modern H. sapiens brain size today is 1,330cc.

Neanderthal brain size at birth was similar to that in recent Homo sapiens and most likely subject to similar obstetric constraints. Neanderthal brain growth rates during early infancy were higher, however. This pattern of growth resulted in larger adult brain sizes but not in earlier completion of brain growth. Because large brains growing at high rates require large, late-maturing, mothers [Leigh SR and Blomquist GE (2007) in Campbell CJ et al. Primates in perspective; pp 396–407], it is likely that Neanderthal life history was similarly slow, or even slower-paced, than in recent H. sapiens.

reply to post by Antigod

reply to post by Antigod

they aren't my claims that IQ heritability increases with age. That's the observation of specialists in the field of human intelligence with years of study behind them.

As clarified earlier, it's old dogma now disputed. Current findings in neuroplasticity controvert the mistaken notion that the so-called heritability of intelligence increases with age. Neuroplasticity may be controversial in a subset of committed geneticists who left school years ago and haven't been keeping up, but it's a respected and exciting science.

Neuroplasticity can be defined as the ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function and connections.

Neuroplasticity, also known as brain plasticity, is an umbrella term that encompasses both synaptic plasticity and non-synaptic plasticity—it refers to changes in neural pathways and synapses which are due to changes in behavior, environment and neural processes, as well as changes resulting from bodily injury.[1] Neuroplasticity has replaced the formerly-held position that the brain is a physiologically static organ, and explores how - and in which ways - the brain changes throughout life.[2]

Neuroplasticity occurs on a variety of levels, ranging from cellular changes due to learning, to large-scale changes involved in cortical remapping in response to injury. The role of neuroplasticity is widely recognized in healthy development, learning, memory, and recovery from brain damage. During most of the 20th century, the consensus among neuroscientists was that brain structure is relatively immutable after a critical period during early childhood. This belief has been challenged by findings revealing that many aspects of the brain remain plastic even into adulthood.[3]

Also see: Aging and neuroplasticity.

2004, if you can access: Neuroplasticity: changes in grey matter induced by training.

reply to post by Antigod


Need the link to evaluate the paper, but based on what you posted - while the study seems to show heritability, it does NOT even try to distinguish between genetic and epigenetic inheritance.

soficrow


Need the link to evaluate the paper, but based on what you posted - while the study seems to show heritability, it does NOT even try to distinguish between genetic and epigenetic inheritance.

KEY POINT No study can distinguish between genetic and "epigenetic" inheritance.
That would imply one could eliminate one or the other which cannot done.

reply to post by soficrow


The larger Neanderthal brain was "overlooked" for a time but now it's a matter of hot debate as art and culture (paintings, jewelry, musical instruments) have been found at what are held as Neanderthal sites. Here's just one of the articles: www.psychologytoday.com...

I think a lot of tripe emanated out of the "snobby" 19th and early 20th centuries when these kind of fields developed that ended up influencing opinions about early man. Putting the time period in a little context, there were extraordinary social pressures and unrest occurring at the dawn of the Industrial Age. Reading some of the sociological and philosophical literature from this time period is really eye opening in illustrating that replacement of "divine right" with "elite right" in this time of turbulence. In the case of the Neanderthal, my guess was that Neanderthal was dismissed as being equal to us simply because Neanderthal did not survive; ergo, they must be inferior. However, that is just a guess. Today, views of just what Neanderthal was and represented has been changing a great deal and for at least a decade. The concept of "caveman" may still be proliferate in the public's mind as that's what they learned in their textbooks, but I am under the distinct impression that that is a very dated view due to discoveries made that indicate the use of linens and more by these uncouth "cavemen".

Here's an argument about why the larger brain size of Neanderthal didn't matter:
www.smithsonianmag.com...

I don't know if I agree with it at all, personally, because I think we tend to consistently undersell the brain functionality of our neighbors on this planet (speciesism). My point in this post, however, is to observe that opinions in regards to Neanderthals are in flux and not as prone to dogmatism as they were in the snobby 19th century.

soficrow
reply to post by Antigod

 

reply to post by Antigod

 

they aren't my claims that IQ heritability increases with age. That's the observation of specialists in the field of human intelligence with years of study behind them.

As clarified earlier, it's old dogma now disputed. Current findings in neuroplasticity controvert the mistaken notion that the so-called heritability of intelligence increases with age. Neuroplasticity may be controversial in a subset of committed geneticists who left school years ago and haven't been keeping up, but it's a respected and exciting science.

Neuroplasticity can be defined as the ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function and connections.

Neuroplasticity, also known as brain plasticity, is an umbrella term that encompasses both synaptic plasticity and non-synaptic plasticity—it refers to changes in neural pathways and synapses which are due to changes in behavior, environment and neural processes, as well as changes resulting from bodily injury.[1] Neuroplasticity has replaced the formerly-held position that the brain is a physiologically static organ, and explores how - and in which ways - the brain changes throughout life.[2]

Neuroplasticity occurs on a variety of levels, ranging from cellular changes due to learning, to large-scale changes involved in cortical remapping in response to injury. The role of neuroplasticity is widely recognized in healthy development, learning, memory, and recovery from brain damage. During most of the 20th century, the consensus among neuroscientists was that brain structure is relatively immutable after a critical period during early childhood. This belief has been challenged by findings revealing that many aspects of the brain remain plastic even into adulthood.[3]

Also see: Aging and neuroplasticity.

2004, if you can access: Neuroplasticity: changes in grey matter induced by training.

edit on 14/2/14 by soficrow because: (no reason given)

edit on 14/2/14 by soficrow because: (no reason given)

edit on 14/2/14 by soficrow because: (no reason given)

Disputed by you. I'm not seeing any links to people who study this subject arguing that IQ gets less heritable with age. Just you..

Also, I'm not sure you're grasping epigenetics. You inherit traits from your parents that get switched on or off by environmental factors. this is the interaction between genes and environment. You still inherit the gene with the on/off from a parent. It's still hereditary.

The neuroplasticity subject is a switch and bait on your part. You've still not shown anything that shows IQ heritability declines with age. Neuroplasticity is a side show to distract from the fact you've not posted anything to suppport your case. The Neuroplasticity effect would come into 'environment'. You can't endlessly boost someones brain power by training it, there are limits.

As for the Neanderthal brain size... try that with someone who didn't study bio anth. It's the brain size relative to body mass that matters, unless you have the size of those neanderthals bodies those numbers are meaningless. Add into that their visial processing areas were much larger. In fact we seem to have interbred with them a fair bit (maybe their had a gene for myopia?). FYI, modern human brain sizes vary through the historical era a fair bit, mainly due to nutrition affecting growth. The smaller the body, the smaller the brain. Its the RELATIVE size that's critical.

You see the relative brain size of hominids increase gradually from the chimp human split point.

Whitealice is quite right. There is plenty of evidence that Neanderthals functioned cognitively in a very smilar way to modern humans. There's ample evidence they had art (there are smothed ochre 'crayons') and jewellery (wolf tooth pendant) ritual in their burials etc. There is also evidence of musical instruments (bone flute in croatia).

Need the link to evaluate the paper, but based on what you posted

Google the text lazybones. Link below:
www.sciencedirect.com...

reply to post by BDBinc

KEY POINT No study can distinguish between genetic and "epigenetic" inheritance.
That would imply one could eliminate one or the other which cannot done.

As I understand it, genes are identifiable as such, not just by their protein products; misfolded proteins (for example, resulting from epigenetic influences) can be identified by their shape (and assuming the "normal" form is known). Are you saying it's all deductive assumptions?

reply to post by WhiteAlice

...opinions in regards to Neanderthals are in flux and not as prone to dogmatism as they were in the snobby 19th century.

Perhaps, but I think antigod was quite right in his observation (below) - the dogma remained in the textbooks into this century. You're right in that Neanderthal brain size is now a bit of a controversy - some researchers are just tripping over themselves trying to prove their cranial capacity did not relate to cognitive ability. lol.

I've never ever seen an anthropolgist deny that earlier versions of our species were less intelligent because of their overall smaller brains. You see this proudly trotted out in class, the line up of replica crania from homo habilis to modern man, and the increase in brain size with each one as proof of greater intelligence

oops. double

reply to post by Antigod


Not sure what you think it is, but neuroplasticity is about how environmental influences affect brain structure - as well as its function and connections - and incidentally, how said structure, function and connections impact intelligence. Rather amazing, and certainly relevant. Not sure what you think epigenetics is, but my take: "….epigenetics is the study of heritable changes in gene activity that are not caused by changes in the DNA sequence." You're right, epigenetic changes are heritable, but NOT "genetically heritable" in that they do not affect genes - just genes' activity. And as far as the "heritability of intelligence" goes - it's definitely controversial. Here's a taste of some recent work.

On the Nature and Nurture of Intelligence and Specific Cognitive Abilities: The More Heritable, the More Culture Dependent

….The findings are consistent with our hypothesis that heritability coefficients differ across cognitive abilities as a result of differences in the contribution of genotype-environment covariance. The counterintuitive finding that the most heritable abilities are the most culture-dependent abilities sheds a new light on the long-standing nature-nurture debate of intelligence.

The Heritability of Intelligence: Not What You Think

….To be clear: these findings do not mean that differences in intelligence are entirely determined by culture. Numerous researchers have found that the structure of cognitive abilities is strongly influenced by genes (although we haven’t the foggiest idea which genes are reliably important). What these findings do suggest is that there is a much greater role of culture, education, and experience in the development of intelligence than mainstream theories of intelligence have assumed. Behavioral genetics researchers– who parse out genetic and environmental sources of variation– have often operated on the assumption that genotype and environment are independent and do not covary. These findings suggests they very much do.

….these recent findings by Kees-Jan Kan and colleagues suggest just the opposite: The bigger the difference in cognitive ability between blacks and whites, the more the difference is determined by cultural influences.**

….at the very least, these findings should make you think twice about the meaning of the phrase “heritability of intelligence.” Instead of an index of how “genetic” an IQ test is, it’s more likely that in Western society– where learning opportunities differ so drastically from each other– heritability is telling you just how much the test is influenced by culture.