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William_the_Bloody · 02-06-2016, 02:04 AM

Human Intelligence: Are some people smarter than others?

Despite time constraints I will try not to be intellectually lazy with this one, as it is probably one of the most important subjects I will cover in my journal. Despite this, I only have free access to scholarly article if I drive to the University I graduated from, so I will largely be relying on articles that cite scientific studies.

It is quite apparent that physical inequality exists, it is visually noticeable, we can see it before our eyes, but because we still know so little about the human brain, the scientific evidence to support intellectual inequality, at least on a significant level, is less clear. So I'll attempt to answer three major questions...

1) Does genetic differentiation lead to notable differences in individual intelligence?
2) Is there a scientific reliable way to measure intelligence? (Ie; IQ testing)
3) Does intelligence lead to inevitable income inequality? (ie ; a correlation with IQ and income)

Human Intelligence Part 1

1) Does genetic differentiation lead to notable differences in individual intelligence?

There is strong irrefutable evidence that our intelligence is in part biologically determined. First we know that some humans are born with intellectual disabilities, (retarded; a term still used in the US) while others are seemingly born gifted (genius) with the ability to solve complex equations within a very quick timeframe.

We also know that this seems to be a hereditary in that a child who is born a genius, or retarted, or bright, but with some sort of learning disability, will often have a brother or sister who displays the same features or challenges in their life.

Some of the strongest evidence used to prove that intelligence is hereditary, and therefore not solely environmental has come from the studying identical twins that have grown up in different households, as the article below points out...

Most twins are raised together by the same parent(s) and in the same home, and so they share similar environments as well as similar genes. Yet even when twins are raised separately (perhaps because they have been adopted and raised by different parents), they typically have similar IQ scores (Bouchard & McGue, 1981; N. Brody, 1992; Mackintosh, 1998; Plomin & Petrill, 1997). In a review of many twin studies, Bouchard and McGue (1981) found these average (median) correlations:

Correlations of Twins’ IQs:
Identical twins raised in the same home .86
Identical twins raised in different homes .72

These are pretty high correlations, and the same reigns true for adoptive children whose IQ's more closely resembled their hereditary parents that their adoptive parents.

Another way to separate the effects of heredity and environment is to compare adopted children with both their biological and adoptive parents. Adopted children tend to be similar to their biological parents in genetic makeup. Their environment, of course, more closely matches that of their adoptive parents. Researchers have found that adopted children’s IQ scores are more highly correlated with their biological parents’ IQs than with their adoptive parents’

Still the .72 correlation would suggest that environment still plays a role, and there is the bigger problem of the IQ tests themselves, and their ability to reliably be able to accurately define and measure intelligence, so I will try to leave this aside for now (though it appears to be next to impossible) when examining the evidence of the brain itself. Just what has science found?

At least since the mid nineteenth century, scientists have been trying to find a link between brain size and intelligence, which would lead to scientists theorizing that intelligence is linked to brain size in comparison to a creatures body mass, which gives humans a steep edge over other animals in their taxonomy, and a recent study seems to back this hypothesis up...

A research team led by University of Wyoming's Sarah Benson-Amram found that carnivore species with relatively larger brains that are proportionate to their body size are better at completing problem-solving tasks. The team chose 140 animals from 39 different mammalian carnivore species and presented them with a new problem-solving task.

The animals involved in the study included arctic foxes, polar bears, tigers, spotted hyenas and wolves, among others. The team presented each animal with a metal box containing their favorite food. They were given only 30 minutes to extract it. The metal box can be opened by a sliding bolt latch. Results showed that animals with larger brains that are proportionate to their body size were more successful in gaining access to the food compared to the animals with smaller brains.

When It Comes To Intelligence, Brain Size Matters: Study : SCIENCE : Tech Times

but the real question is this, Is the size of human brains between individuals enough to result in one person being more intelligent than another? some recent scientific studies suggests that it does...

In 2005, a psychologist using brain scan imaging to determine brain size found evidence that people with larger brains tended to score higher on IQ tests.

This study’s best estimate of the correlation between brain volume and intelligence is 0.33. The correlation is higher for females than males. It is higher for adults than children. Regardless of theexamined, the correlation between brain volume and intelligence is always positive. It is very clear that brain volume and intelligence are related.

http://www.people.vcu.edu/~mamcdani/...%20article.pdf

The study was controversial in that it showed that men (whose brains generally weigh slightly more) on average had slightly higher IQ scores, but it was also noted that the ratio between men and women picked for the test was largely unequal, and although I am not a scientist, my understanding is that .33 is regarded as weak to moderate correlation at best. The study and brain scanning imaging has gone under critique since, but nevertheless further studies have supported this hypothesis.

In 2012 a group of neuroscientists released their findings that once again showed a link between brain size and intelligence.

Another notable genetic sequence, located within the HMGA2 gene on chromosome 12, was linked with intracranial volume — in other words, the space inside your skull that marks the outer limit as to how big your brain can get. At this spot, every C-allele variant was linked to not only lower intracranial volume, but also to lower IQ scores on the Multidimensional Aptitude Battery, a measure of intelligence.

Specific Genes Linked to Big Brains and Intelligence | Brain Size & Genetics

The largest brain study of its kind had found a gene linked to intelligence, a small piece in the puzzle as to why some people are smarter than others.
A variant of this gene "can tilt the scales in favour of a higher intelligence", says study leader Paul Thompson, stressing though that genetic blessings were not the only factor in brainpower.

Searching for a genetic explanation for brain disease, the scientists stumbled upon a minute variant in a gene called HMGA2 among people who had larger brains and scored higher on standardised IQ tests

Tiny gene change affects brain size, IQ › News in Science (ABC Science)

In short, they discovered a gene that effects a persons brain size, and the bigger the brain, the higher they scored on IQ tests. This reinforces a previous study by UK scientists, who found that bigger brains were less effected by cognitive deterioration than smaller brains as they got older.

Big heads really are smarter | UK news | The Guardian

Still many scientists argue that it is not necessarily the brain size that matters per say, but other factors which may or may not be enabled by a big brain...

They found that people with high IQ scores had significantly more grey matter in 24 of the regions than people with lower scores. Many of the areas, which are spread throughout the brain, are known to be related to memory, attention and language. Their results are reported online in Neuroimage1.Haier believes that different aspects of intelligence might depend on the amount of grey matter in these different brain regions. "This may be why one person is quite good at mathematics and not so good at spelling, and another person, with the same IQ, has the opposite pattern of abilities," he says.

Grey matter matters for intellect : Nature News

and other scientists suggest that it is not necessarily the brain size that matters, but how well the neurons and synapses are firing...

Rather, scientists now argue, it is a brain's underlying organization and molecular activity at its synapses (the communication junctions between neurons through which nerve impulses pass) that dictate intelligence.how neurons or nerve cells and synapses are organized—are the keys to determining information-processing capacity. Manger speculates that cetacean brains are large not because of intelligence but instead due to an abundance of fatty glial cells (non-nerve cells serving as a supporting tissue), which may be present to provide warmth in cold waters for the information-processing neurons in the brain's interior.

Fact or Fiction: When It Comes to Intelligence, Does Brain Size Matter? - Scientific American

and of course, as already mentioned, there is now direct evidence that our genes contribute to our intellect, or lack there of it...

We know that genetics plays a major role in intelligence but until now haven’t known which genes are relevant. This research highlights some of genes involved in human intelligence, and how they interact with each other,” said Dr Johnson, a Consultant Neurologist at Imperial College Healthcare and Deputy Head of the Center for Clinical Translation in the Division of Brain Sciences at Imperial College London.

and the good news...“Our research suggests that it might be possible to work with these genes to modify intelligence.

Intelligence 'networks' discovered in brain for the first time

All in all, the evidence would suggest that there is a hereditary basis for our intelligence, and that genetic differentiation does appear to suggest there are some differing levels of intelligence amongst humans, though it should be noted that their does not appear to be a strong consensus within the scientific community as to what the primary factors are, and the sought after link between brain size and intelligence only has a .25 correlation, which is pretty weak.

This is worrisome for me, we had all sorts of scientific studies in the early and mid twentieth century that showed some promise of correlation but now seem to be defunct. I obviously would choose science over religion and philosophy when coming to a theoretical decision, but I think we have to be wary of positivism as well, as scientific theories are nothing more than just theories, in which the conclusions of one study could be proven wrong tomorrow.

We seem to know so little about the human brain that I have some series doubts on whether we can accurately measure intelligence, I guess I'll find out in researching part 2.

02-06-2016, 02:04 AM	#29 (permalink)
William_the_Bloody Music Addict Join Date: Nov 2012 Location: Sunnydale Cemetary Posts: 2,093	Human Intelligence: Are some people smarter than others? Despite time constraints I will try not to be intellectually lazy with this one, as it is probably one of the most important subjects I will cover in my journal. Despite this, I only have free access to scholarly article if I drive to the University I graduated from, so I will largely be relying on articles that cite scientific studies. It is quite apparent that physical inequality exists, it is visually noticeable, we can see it before our eyes, but because we still know so little about the human brain, the scientific evidence to support intellectual inequality, at least on a significant level, is less clear. So I'll attempt to answer three major questions... 1) Does genetic differentiation lead to notable differences in individual intelligence? 2) Is there a scientific reliable way to measure intelligence? (Ie; IQ testing) 3) Does intelligence lead to inevitable income inequality? (ie ; a correlation with IQ and income) Human Intelligence Part 1 1) Does genetic differentiation lead to notable differences in individual intelligence? There is strong irrefutable evidence that our intelligence is in part biologically determined. First we know that some humans are born with intellectual disabilities, (retarded; a term still used in the US) while others are seemingly born gifted (genius) with the ability to solve complex equations within a very quick timeframe. We also know that this seems to be a hereditary in that a child who is born a genius, or retarted, or bright, but with some sort of learning disability, will often have a brother or sister who displays the same features or challenges in their life. Some of the strongest evidence used to prove that intelligence is hereditary, and therefore not solely environmental has come from the studying identical twins that have grown up in different households, as the article below points out... Most twins are raised together by the same parent(s) and in the same home, and so they share similar environments as well as similar genes. Yet even when twins are raised separately (perhaps because they have been adopted and raised by different parents), they typically have similar IQ scores (Bouchard & McGue, 1981; N. Brody, 1992; Mackintosh, 1998; Plomin & Petrill, 1997). In a review of many twin studies, Bouchard and McGue (1981) found these average (median) correlations: Correlations of Twins’ IQs: Identical twins raised in the same home .86 Identical twins raised in different homes .72 These are pretty high correlations, and the same reigns true for adoptive children whose IQ's more closely resembled their hereditary parents that their adoptive parents. Another way to separate the effects of heredity and environment is to compare adopted children with both their biological and adoptive parents. Adopted children tend to be similar to their biological parents in genetic makeup. Their environment, of course, more closely matches that of their adoptive parents. Researchers have found that adopted children’s IQ scores are more highly correlated with their biological parents’ IQs than with their adoptive parents’ Still the .72 correlation would suggest that environment still plays a role, and there is the bigger problem of the IQ tests themselves, and their ability to reliably be able to accurately define and measure intelligence, so I will try to leave this aside for now (though it appears to be next to impossible) when examining the evidence of the brain itself. Just what has science found? At least since the mid nineteenth century, scientists have been trying to find a link between brain size and intelligence, which would lead to scientists theorizing that intelligence is linked to brain size in comparison to a creatures body mass, which gives humans a steep edge over other animals in their taxonomy, and a recent study seems to back this hypothesis up... A research team led by University of Wyoming's Sarah Benson-Amram found that carnivore species with relatively larger brains that are proportionate to their body size are better at completing problem-solving tasks. The team chose 140 animals from 39 different mammalian carnivore species and presented them with a new problem-solving task. The animals involved in the study included arctic foxes, polar bears, tigers, spotted hyenas and wolves, among others. The team presented each animal with a metal box containing their favorite food. They were given only 30 minutes to extract it. The metal box can be opened by a sliding bolt latch. Results showed that animals with larger brains that are proportionate to their body size were more successful in gaining access to the food compared to the animals with smaller brains. When It Comes To Intelligence, Brain Size Matters: Study : SCIENCE : Tech Times but the real question is this, Is the size of human brains between individuals enough to result in one person being more intelligent than another? some recent scientific studies suggests that it does... In 2005, a psychologist using brain scan imaging to determine brain size found evidence that people with larger brains tended to score higher on IQ tests. This study’s best estimate of the correlation between brain volume and intelligence is 0.33. The correlation is higher for females than males. It is higher for adults than children. Regardless of theexamined, the correlation between brain volume and intelligence is always positive. It is very clear that brain volume and intelligence are related. http://www.people.vcu.edu/~mamcdani/...%20article.pdf The study was controversial in that it showed that men (whose brains generally weigh slightly more) on average had slightly higher IQ scores, but it was also noted that the ratio between men and women picked for the test was largely unequal, and although I am not a scientist, my understanding is that .33 is regarded as weak to moderate correlation at best. The study and brain scanning imaging has gone under critique since, but nevertheless further studies have supported this hypothesis. In 2012 a group of neuroscientists released their findings that once again showed a link between brain size and intelligence. Another notable genetic sequence, located within the HMGA2 gene on chromosome 12, was linked with intracranial volume — in other words, the space inside your skull that marks the outer limit as to how big your brain can get. At this spot, every C-allele variant was linked to not only lower intracranial volume, but also to lower IQ scores on the Multidimensional Aptitude Battery, a measure of intelligence. Specific Genes Linked to Big Brains and Intelligence \| Brain Size & Genetics The largest brain study of its kind had found a gene linked to intelligence, a small piece in the puzzle as to why some people are smarter than others. A variant of this gene "can tilt the scales in favour of a higher intelligence", says study leader Paul Thompson, stressing though that genetic blessings were not the only factor in brainpower. Searching for a genetic explanation for brain disease, the scientists stumbled upon a minute variant in a gene called HMGA2 among people who had larger brains and scored higher on standardised IQ tests Tiny gene change affects brain size, IQ › News in Science (ABC Science) In short, they discovered a gene that effects a persons brain size, and the bigger the brain, the higher they scored on IQ tests. This reinforces a previous study by UK scientists, who found that bigger brains were less effected by cognitive deterioration than smaller brains as they got older. Big heads really are smarter \| UK news \| The Guardian Still many scientists argue that it is not necessarily the brain size that matters per say, but other factors which may or may not be enabled by a big brain... They found that people with high IQ scores had significantly more grey matter in 24 of the regions than people with lower scores. Many of the areas, which are spread throughout the brain, are known to be related to memory, attention and language. Their results are reported online in Neuroimage1.Haier believes that different aspects of intelligence might depend on the amount of grey matter in these different brain regions. "This may be why one person is quite good at mathematics and not so good at spelling, and another person, with the same IQ, has the opposite pattern of abilities," he says. Grey matter matters for intellect : Nature News and other scientists suggest that it is not necessarily the brain size that matters, but how well the neurons and synapses are firing... Rather, scientists now argue, it is a brain's underlying organization and molecular activity at its synapses (the communication junctions between neurons through which nerve impulses pass) that dictate intelligence.how neurons or nerve cells and synapses are organized—are the keys to determining information-processing capacity. Manger speculates that cetacean brains are large not because of intelligence but instead due to an abundance of fatty glial cells (non-nerve cells serving as a supporting tissue), which may be present to provide warmth in cold waters for the information-processing neurons in the brain's interior. Fact or Fiction: When It Comes to Intelligence, Does Brain Size Matter? - Scientific American and of course, as already mentioned, there is now direct evidence that our genes contribute to our intellect, or lack there of it... We know that genetics plays a major role in intelligence but until now haven’t known which genes are relevant. This research highlights some of genes involved in human intelligence, and how they interact with each other,” said Dr Johnson, a Consultant Neurologist at Imperial College Healthcare and Deputy Head of the Center for Clinical Translation in the Division of Brain Sciences at Imperial College London. and the good news...“Our research suggests that it might be possible to work with these genes to modify intelligence. Intelligence 'networks' discovered in brain for the first time All in all, the evidence would suggest that there is a hereditary basis for our intelligence, and that genetic differentiation does appear to suggest there are some differing levels of intelligence amongst humans, though it should be noted that their does not appear to be a strong consensus within the scientific community as to what the primary factors are, and the sought after link between brain size and intelligence only has a .25 correlation, which is pretty weak. This is worrisome for me, we had all sorts of scientific studies in the early and mid twentieth century that showed some promise of correlation but now seem to be defunct. I obviously would choose science over religion and philosophy when coming to a theoretical decision, but I think we have to be wary of positivism as well, as scientific theories are nothing more than just theories, in which the conclusions of one study could be proven wrong tomorrow. We seem to know so little about the human brain that I have some series doubts on whether we can accurately measure intelligence, I guess I'll find out in researching part 2.