Oct 1, 2013 08:00 AM ET // by Emily Sohn http://news.discovery.com/human/life/can-intelligence-really-be-measured-131001.htm
Every year, the MacArthur Foundation bestows large financial grants on a group of people who are doing exceptionally creative or important work.
MacArthur fellowships are often called “genius grants,” and grant-winners tend to be unusually motivated, passionate and forward thinking. But are they geniuses? The annual conversation that ensues raises questions about what it means to be intelligent and whether that’s something that can be cultivated, measured or even defined.
Despite decades of research into how different brains work, experts said, there are no easy answers. Scientists now know that there are multiple types of intelligence. There's a strong genetic component to certain aspects of intelligence. And scores on intelligence tests are tightly linked to school performance, future income level, health and more.
Is IQ a Good Measure of Intelligence?
Much is made of a person's IQ score. But is there really anything to that number? But IQ scores are far from the only factor that determines how well people do in life. Also, conversations about innate differences in intelligence continue to make people uneasy, probably because there is a long history of racism, classism, sexism and even religious discrimination tied up in discussions about who is smarter than whom. “The field is just fraught with controversy after controversy,” said Randall Engle, a psychologist at the Georgia
Institute of Technology in Atlanta. “There are group differences all over the place in intelligence measures and that just adds to the controversy. It’s hard for the field to come to grips with what’s understandable about this in the midst of all this craziness.” Researchers have been interested in understanding the nature of intelligence since at least the 1800s, but early studies were hampered by complications.
Part of the problem was that intelligence tests were designed before anyone had come up with a specific definition of what they were trying to measure, Engle said. What’s more, British scientist Sir Francis Galton, who was the first to use statistics to test whether intelligence could be inherited, was also a eugenicist, and beliefs that good traits were inborn led to forced sterilizations and other terrible outcomes.
In the early 1900s, French psychologist Alfred Binet developed a test to identify children who might need extra help in school, and his work was incorporated into the Stanford-Binet Intelligence Scales, which originally focused on verbal skills. That and other modern IQ tests have changed over the years as new research changes our understanding of what intelligence is.
Generally, Engle said, different IQ tests correlate well with each other and scores tend to be linked to real-world outcomes. Compared to people who score lower on the tests, for example, people with the highest IQs file more patents, publish more academic papers, and earn higher incomes.
But scoring well on an IQ test doesn’t predict success, nor does a relatively average or lower score predict a life of misery.
That’s because having a high IQ is like owning a car with a big engine, said David Lubinksi, psychologist and co-director of the Study of
Mathematically Precocious Youth at Vanderbilt University in Nashville, Tenn. “If there’s no gas in your car you’re not going to go anywhere. If road conditions are bad, you’re not going to go anywhere,” he said. In the case of intelligence, you need good health, hard work and motivation to take advantage of inherent brainpower.
Another complication is that intelligence comes in many forms. One category is crystallized intelligence, Engle said, which measures how much knowledge a person has acquired and that is highly correlated to education level.
On the flip side is fluid intelligence, which is the ability to reason and solve new problems. Studies of twins show that fluid intelligence is largely genetic. Identical twins are much more similar to each other on measures of fluid intelligence than fraternal twins are.

But, according to recent research, that is true only for people with high socioeconomic status, at least in the United States, where access to education varies by zip code. In other words, genes only kick in to influence IQ when people are already getting a relatively good education.
As scientists learn more about the components of intelligence, they are developing new ways to assess nuances in the way people think.
Traditional IQ tests have long focused on math and verbal skills, Lubinksi said. Now, though, it’s becoming clear that the ability to think spatially and rotate shapes in the mind’s eye is essential for pilots, orthopedic surgeons, architects and other occupations.
Some newer tests evaluate those visualization skills.
Even as testing gets more refined, debates continue about whether IQ tests should be used at all. The military has used intelligence testing as a way to place people in the toughest posts, and experts said that evaluations can be useful in professional and educational settings, too -- as long as they’re used responsibly and sensitively.
For kids who are struggling in school, for instance, IQ tests can help determine whether they’re so intelligent that they’re bored or if they have cognitive deficits that require special attention. Determining mental strengths and weaknesses can also help teachers tailor education and steer students towards jobs that best fit their skills.
On the other hand, experts said, it wouldn’t be a good idea to test every child’s IQ and announce the number because that would unnecessarily and unfairly shape expectations. “It’s like every other tool,” Lubinski said. “It can cause harm, and it can be of great service. There are examples of both.” As for MacArthur fellows, IQ tests have nothing to do with who wins and “genius” is probably not the right word, Engle said. “I know two MacArthur award winners,” he said. “They’re pretty normal people who have done some interesting things.”

January 22, 2005 University Of California, Irvine http://www.sciencedaily.com/releases/2005/01/050121100142.htm
Irvine, Calif. (January 20, 2005) -- While there are essentially no disparities in general intelligence between the sexes, a UC Irvine study has found significant differences in brain areas where males and females manifest their intelligence.
The study shows women having more white matter and men more gray matter related to intellectual skill, revealing that no single neuroanatomical structure determines general intelligence and that different types of brain designs are capable of producing equivalent intellectual performance.
“These findings suggest that human evolution has created two different types of brains designed for equally intelligent behavior,” said
Richard Haier, professor of psychology in the Department of Pediatrics and longtime human intelligence researcher, who led the study with colleagues at UCI and the University of New Mexico. “In addition, by pinpointing these gender-based intelligence areas, the study has the potential to aid research on dementia and other cognitive-impairment diseases in the brain.”
In general, men have approximately 6.5 times the amount of gray matter related to general intelligence than women, and women have nearly 10 times the amount of white matter related to intelligence than men. Gray matter represents information processing centers in the brain, and white matter represents the networking of – or connections between – these processing centers.
This, according to Rex Jung, a UNM neuropsychologist and co-author of the study, may help to explain why men tend to excel in tasks requiring more local processing (like mathematics), while women tend to excel at integrating and assimilating information from distributed gray-matter regions in the brain, such as required for language facility. These two very different neurological pathways and activity centers, however, result in equivalent overall performance on broad measures of cognitive ability, such as those found on intelligence tests.
The study also identified regional differences with intelligence. For example, 84 percent of gray-matter regions and 86 percent of whitematter regions involved with intellectual performance in women were found in the brain’s frontal lobes, compared to 45 percent and zero percent for males, respectively. The gray matter driving male intellectual performance is distributed throughout more of the brain.
According to the researchers, this more centralized intelligence processing in women is consistent with clinical findings that frontal brain injuries can be more detrimental to cognitive performance in women than men. Studies such as these, Haier and Jung add, someday may help lead to earlier diagnoses of brain disorders in males and females, as well as more effective and precise treatment protocols to address damage to particular regions in the brain.
For this study, UCI and UNM combined their respective neuroimaging technology and subject pools to study brain morphology with magnetic resonance imaging. MRI scanning and cognitive testing involved subjects at UCI and UNM. Using a technique called voxelbased morphometry, Haier and his UCI colleagues converted these MRI pictures into structural brain “maps” that correlated brain tissue volume with IQ.
Dr. Michael T. Alkire and Kevin Head of UCI and Ronald A. Yeo of UNM participated in the study, which was supported in part by the
National Institute of Child Health and Human Development.

Last updated: 30 July 2013 at 5am PST Written by Honor Whiteman
Researchers have discovered that the longer a mother breastfeeds, the more intelligent their child will become later in life.
A study, published in the journal JAMA Pediatrics has provided evidence that breastfeeding in infancy leads to better cognitive development later in life, but it depends upon how long the infant is breastfed.
Researchers from Boston Children's Hospital say previous work has suggested that breast milk can boost an infant's brain as it contains docosahexaenoic acid (DHA), which helps cognitive development. They add that fish intake during lactation is a good source of DHA.
The study authors say: "Nutrients in breast milk, such as n-3 fatty acid DHA, may benefit the developing brain. A major determinant of breast milk DHA content is the mother's diet, and fish is a rich source of DHA.
"In pregnancy, greater maternal fish intake (particularly fish low in mercury contamination) is associated with better childhood cognitive outcomes, but the extent to which maternal fish intake during lactation accounts for the relationship between breastfeeding and cognition has not been reported."
The researchers analyzed 1,312 mothers and children to see the relationship between breastfeeding duration and child cognition at ages 3 and 7 years.
Children were measured on whether they were breastfed milk only, received mixed feeds, weaned or were never breastfed. For 1,224 of the participants at age 3, the mean duration of any breastfeeding, including mixed feeds, was 6.4 months. The mean duration for breastfeeding only was 2.4 months.
Fish intake by mothers during lactation was also analyzed to see how this would affect associations of infant feeding and later cognition.
A series of cognitive tests were carried out, including:
 Peabody Picture Vocabulary Test at age 3
 Wide Range Assessment of Visual Motor Abilities at age 3 and 7
 Kaufman Brief Intelligence Test and Wide Range Assessment of Memory and Learning at age 7
The results showed that longer breastfeeding duration was linked with higher test scores in the Peabody Picture Vocabulary test at age
3, and higher intelligence on the Kaufman Brief Intelligence Test at age 7.
However, results showed that longer breastfeeding duration was not linked to any improvement in the Wide Range Assessment of
Memory and Learning scores.
Children whose mothers had high fish intake during lactation (greater than or equal to 2 servings per week) had stronger results in the
Wide Range Assessment of Visual Motor Abilities at age 3, compared with children of women who had lower fish intake (less that 2 servings per week).
The study authors conclude:
"Our results support a causal relationship of breastfeeding in infancy with receptive language at age 3 and with verbal and nonverbal IQ at school age.
These findings support national and international recommendations to promote exclusive breastfeeding through age 6 months and continuation of breastfeeding through at least age 1 year."

Dr. Dimitri Christakis, of the Seattle Children's Hospital Research Institute, has written an editorial in JAMA Pediatrics to accompany the researchers' study, calling for women to be given better opportunities to breastfeed for longer. Dr. Christakis says:
"Workplaces need to provide opportunities and spaces for mothers to use them.
Breastfeeding in public should be destigmatized. Clever social media campaigns and high-quality public service announcements might help with that."
The problem, Dr. Dimitri Christakis adds, "is not so much that most women do not initiate breastfeeding, it is that they do not sustain it."
He continues: "In the US about 70% of women overall initiate breastfeeding, although only 50% of African American women do.
However, by six months, only 35% and 20%, respectively, are still breastfeeding."
It would, however, appear that breastfeeding is on the increase in the US. In an article covered by Medical News Today on 1 August
2013, the CDC suggested that within a 10-year period between 2000 and 2010, the number of babies who were first breastfed rose from 71% in 2000 to 77% in 2010.

By Paul Bentley for the Daily Mail Updated: 04:23 EST, 30 March 2010 http://www.dailymail.co.uk/sciencetech/article-1261490/Is-proof-smoking-lowers-IQ-Study-suggests-20-day-drastically-reduces-mental-capacity.html
Blowing the brain cells away: Those who smoke of a pack averaged an IQ seven points lower than non-smokers. Smoking has long been known to damage lungs and cause heart disease. But it could also lower your IQ, research has found. Young people who smoke regularly are likely to have markedly lower intelligence levels than those who do not smoke, and, according to the study of
20,000 young adults, the heavier the smoker, the lower the IQ. Those who smoke a pack or more of cigarettes a day averaged an IQ seven and a half points lower than that of those who do not smoke. A typical 18 to 21-year-old smoker was found to have an IQ of 94, while non-smokers of the same age averaged 101. Those who smoked more than a pack a day had particularly low IQs of around 90.
An average intelligence IQ score ranges from 84 to 116 points.
Crucially, brothers scored differently depending on whether or not they smoked. Despite similar environmental conditions, non-smoking siblings achieved higher IQs than their smoking brothers. The results come from a study of 20,000 young men conducted by the Sheba Medical Center at the Tel Hashomer Hospital in Israel. Dr. Mark Weiser, who led the research, said it is unclear whether smoking causes IQ levels to drop or whether less intelligent people are simply more inclined to smoke. 'It was really quite a straightforward study,' he said. 'We looked at cross-sectional data on IQ and smoking cigarettes, and looked at people's smoking status and their IQs. 'IQ scores are lower in male adolescents who smoke compared to non-smokers and in brothers who smoke compared to their non-smoking brothers. The IQs of adolescents who began smoking between ages 18 to 21 are lower than those of non-smokers. 'It's very clear that people with low IQs are the ones who choose to smoke. It's not just a matter of socioeconomic status
- if they are poor or have less education,' he said.
Dr Weiser suggested the results could confirm a previously held conviction that those with lower IQs tend to make poorer decisions regarding their health – that they are more likely to take drugs, eat unhealthy food and exercise less. The study could also be used to prevent smoking in young people by targeting those with lower IQs, Dr Weiser said. Researchers found that 28per cent of the teenagers polled smoked one or more cigarettes a day, three per cent admitted to having smoked in the past, while 68 per cent of the young men had never smoked.
In 2004, researchers from the University of Aberdeen first found a possible link between smoking and reduced mental function. Hundreds of volunteers who had taken part in the Scottish Mental Survey in 1947 aged 11, retook tests 53 years later.
Smokers performed worse than ex-smokers and those who had never smoked.
Scientists cannot yet conclusively explain the link between impaired lung function and cognitive ageing but it has been suggested that smoking could put the brain under oxidative stress, which causes DNA damage.
Breslau N, Paneth N, Lucia VC, Paneth-Pollak R
BACKGROUND: Maternal smoking in pregnancy lowers birth weight. It is unclear, however, whether smoking during pregnancy lowers offspring IQ, and, if it does, whether it is through the smoking effect on fetal growth.
METHOD: Representative samples of low birth weight (<2500 g) and normal birth weight children born in 1983-85 from inner-city and suburban communities in southeast Michigan, USA were assessed at ages 6, 11, and 17, using Wechsler intelligence tests. Smoking during pregnancy was ascertained from mothers at the first assessment; and smoking at any time was ascertained at the first and second assessment. Generalized estimating equation models were used, with children's IQ at all three assessments as outcomes (n =
798).
RESULTS: Without adjustment, offspring of mothers who smoked during pregnancy scored 6.8 IQ points lower than offspring of mothers who never smoked, on average. Low birth weight children scored 5.4 IQ points lower than normal birth weight children, on average. The statistical association of maternal smoking with offspring IQ was confounded by maternal characteristics, chiefly, maternal cognitive ability as measured by IQ and education; adjustment for these factors eliminated the association. By contrast, adjustment for maternal IQ and education as well as smoking during pregnancy had a negligible effect on the low birth weight-related
IQ deficit. Low birth weight did not mediate the association of smoking and lowered IQ in offspring.
CONCLUSION: Maternal smoking during pregnancy is a proxy for a matrix of vulnerabilities for adverse child cognitive development and has no direct causal effect on child's IQ. The relationship of low birth weight and IQ is independent of maternal smoking and maternal cognitive abilities.

Last updated: 16 November 2012 at 12am PST Written by Christine Kearney http://www.medicalnewstoday.com/articles/252876.php
A child's IQ suffers from even minimal levels of exposure to alcohol while in his/her mother's womb, according to a new
study conducted by researchers from the Universities of Bristol and Oxford and published in the journal PLOS ONE.
At present, theories on drinking alcohol moderately during pregnancy vary. Certain official recommendations state that women who are pregnant should completely refrain from drinking, while others say that moderately drinking is okay. Prior research has made for controversial and conflicting opinions on the matter, as well as conflicting evidence regarding how children's IQs are effected by alcohol intake among their mothers.
The report claims that this may be due to the fact that it is often hard to differentiate between whether a child's IQ is affected by the moderate alcohol intake of his/her mother or other lifestyle and social elements, including diet, smoking, age, affluence and education.
For the new study, researchers utilized the Children of the 90s study (ALSPAC) data taken from more than 4,000 mothers and their children. The new trial is thought to be the first to use genetic variation to analyze the impact that mothers' moderate drinking (less than
1-6 units of alcohol a week) has on their child's IQ. Using genetic variation is ideal because each woman has different DNA, which is not linked to lifestyle factors, therefore, this method takes away that possible complication.
In the 4,167 children involved in the study, a strong link was found between 4 genetic alternatives in genes which metabolize alcohol and lower IQ at the age of 8 years old. For each genetic modification a child had, their IQ was found to be 2 points lower. However, this was only observed in children whose mothers reported moderate drinking while pregnant. On the other hand, this link was not found at all among children whose mothers reported no drinking while pregnant, indicating that there is a direct association
between alcohol exposure in the womb and damage to a child's IQ. The report notes that the study did not involve excessive drinkers.
When alcohol is consumed, ethanol is turned to acetaldehyde by a cluster of enzymes. Differences in people's genes that 'encode' these enzymes results in variations in their capability to metabolize the ethanol. Therefore, in people whose genes metabolize slowly, alcohol levels can reach higher points and last longer than those whose enzymes metabolize quickly.
Experts say that 'fast' metabolism of ethanol defends against damage to infants' brain development, due to the fact that smaller amounts of alcohol are exposed to the fetus. However, the exact happenings remain unknown.
Earlier research has been based on evidence observed by other researchers, however, this is not concrete. Observational studies tend to claim that moderate drinking is better than not drinking at all. This is because pregnant women who drink lightly while pregnant have been reported to be educated, healthy and not likely to smoke, which are common factors associated with a child's chance of having a higher IQ, therefore covering the potential risk factors that alcohol exposure could give to the child.
The new trial observed moderate alcohol consumption among more than 4,000 mothers by utilizing a method called Mendelian randomization, a tool which analyzes the associations between exposure and later outcomes by using genetic variants that alter levels of exposure and are not affected by lifestyle habits.
The participants' intake levels were determined by a survey they were given to complete when they were 18 weeks pregnant. It involved questions regarding the average amount consumed, and how often the women consumed alcohol prior to becoming pregnant, during the first trimester, and in the two weeks prior to the first time they felt their child move. One drink was considered one unit of alcohol for this study.

When the mothers were around 32 weeks pregnant, they were asked to complete a second survey, which questioned the average amount of drinking the mothers had consumed on weekdays and weekends. Each mother who said they had consumed alcohol, regardless of whether it was less than one unit a week during the first trimester or when she felt the baby first move, was considered as a drinker while pregnant.
At weeks 18 and 32, the mothers were also asked how many days during the previous month they had consumed two pints of beer, or the same amount in alcohol. Each woman who said that they had done this, even if it was only once in a while, was considered a binge drinker in this particular study and was no longer allowed to be involved in the trial.
At age 8, the children's IQs were tested by researchers utilizing the Wechslet Intelligence Scale for Children, from which an average age adjusted complete score was made.
Dr. Sarah Lewis, lead author of the study, commented on the findings:
"Our results suggest that even at levels of alcohol consumption which are normally considered to be harmless, we can detect differences in childhood IQ, which are dependent on the ability of the fetus to clear this alcohol. This is evidence that even at these moderate levels, alcohol is influencing fetal brain development."
Dr. Ron Gray, from the University of Oxford and research leader, concluded, "This is a complex study but the message is simple: even moderate amounts of alcohol during pregnancy can have an effect on future child intelligence. So women have good reason to choose to avoid alcohol when pregnant."

April 14, 2009 |By Kayt Sukel http://www.scientificamerican.com/article/does-brain-size-matter/
What does brain size say about a creature's mental abilities? Research has shown that lead kills neurons (nerve cells), resulting in smaller brains. It has long been hypothesized that such changes in the brain caused by childhood lead exposure may be behind a higher incidence of poor cognitive performance and criminal behavior. And although it is difficult to disentangle the confounding effects of race, class and economics, a recent study by Kim Dietrich, a professor of environmental health at the University of Cincinnati, found that individuals who suffered from the highest lead exposure as children had the smallest brain sizes—as well as the most arrests.
"That early lead exposure was associated with smaller volumes of cortical gray matter [the parts of the brain rich in neural cell bodies and synapses] in the prefrontal area," he says. "And the fact that we saw both criminal behavior and volume loss in this critical area for executive function is probably more than just a coincidence."
That may be so, however, new scientific studies across several animal species, including humans, are challenging the notion that brain size alone is a measure of intelligence. 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.
Two years ago, Paul Manger, a professor of health sciences at the University of the Witwatersrand in Johannesburg, South Africa, caused quite a stir when he referred to the beloved bottlenose dolphin, owner of a large, nearly human-size brain, as "dumber than a goldfish."
"When you look at cetaceans, they have big brains, absolutely," Manger says. "But if you look at the actual structure of the brain, it's not very complex. And brain size only matters if the rest of the brain is organized properly to facilitate information processing."
He argues that the systems within the brain—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.
Mark Uhen, a vertebrate paleontologist at the Alabama Museum of Natural History, and Lori Marino, a biologist who studies brain evolution of cetaceans and primates at Emory University's Yerkes National Primate Research Center, disagree. Marino says that
Manger's theories discount years of behavioral evidence that show dolphins to be complex thinkers. What's more, she says, the mammals have an unusual brain structure with a different functional map and therefore cannot be compared with other species.
Marino believes that the dolphin's unique brain organization may represent an alternate evolutionary route to complex intelligence—and that molecules released in synapses may provide that alternative path.
A study recently published in Nature Neuroscience by Seth Grant, a neuroscientist at the Wellcome Trust Sanger Institute in
Cambridge, along with Richard Emes, a professor in Bioinformatics at Keele University School of Medicine in North Staffordshire, both in England, suggests that all species have the same basic proteins that act in the synapses.
"If you look at us and fish, we have very different cognitive abilities," Emes says. "But we have roughly the same number of these synaptic proteins. It is the number of interactions and gene duplications of these proteins that provide the brain building blocks for higher level cognitive function.”
Emes, Grant and colleagues agree with Marino and Uhenthat intelligence and differences between species are due to molecular complexity at the synaptic level. "The basic dogma says that the computational properties of the brain are based on the number of

neurons and synapses," Grant says. "But we modify that by saying that the molecular complexity within those synapses is also important."
Grant and Emes looked at where approximately 150 synaptic proteins were released in the nervous systems of yeast, fruit flies and mice. They found that a variation in production and distribution patterns was linked to higher-level brain organization.
"The proteins that you find in yeast are the sort of proteins that are far more likely to be found expressed throughout the brain in uniform quantities," Grant says. "They laid a foundation to make more diverse and different regions of the brain using different combinations and expressions of other, more innovative proteins." He likens these molecular proteins to implements in a toolbox that help to build specialized brain regions. He goes on to say that the different interactions, duplications or deletions of these proteins resulted over time in the evolutionary development of regions like the prefrontal cortex in humans which is involved in higher executive function like planning and goal-directed behavior
Grant says that this finding offers scientists a new way to approach the study of brain evolution and intelligence and, perhaps more importantly, suggests that looking at sheer brain size has very little to offer in understanding cognitive abilities.
"It's clear now that there are wonderful mental abilities in birds even with their relatively small brains, nerve cells and neural connections. But they have complex molecular synapses," says Grant. "My sense is in the next 10 to 20 years our perspectives about the mental capacities of different species will change quite radically."
But the idea that a big brain equals big smarts is not going to go away anytime soon. Though Manger discounts the role of glial cells in intelligence, a posthumous anatomical study of Albert Einstein's brain showed that the scientific genius's brain differed from the brains of other dead scientists only with its greater ratio of glial cells to neurons. But a study of Einstein's brain organization and synaptic molecule configuration still remains to be completed.

By BENEDICT CAREY Published: June 21, 2007 http://www.nytimes.com/2007/06/21/science/21cnd-sibling.html?pagewanted=all
The average difference in I.Q. was slight — three points higher in the eldest child than in the closest sibling — but significant, the researchers said. And they said the results made it clear that it was due to family dynamics, not to biological factors like prenatal environment.
Researchers have long had evidence that firstborns tended to be more dutiful and cautious than their siblings, and some previous studies found significant I.Q. differences. But critics said those reports were not conclusive, because they did not take into account the vast differences in upbringing among families.
Three points on an I.Q. test may not sound like much. But experts say it can be a tipping point for some people — the difference between a high B average and a low A, for instance. That, in turn, can have a cumulative effect that could mean the difference between admission to an elite private liberal-arts college and a less exclusive public one.
Moreover, researchers said yesterday that the results — being published today in separate papers in two journals, Science and
Intelligence — would lead to more intensive study into the family dynamics behind such differences. Though the study was done in men, the scientists said the results would almost certainly apply to women as well.
“I consider these two papers the most important publications to come out in this field in 70 years; it’s a dream come true,” said Frank J.
Sulloway, a psychologist at the Institute of Personality and Social Research at the University of California, Berkeley.
Dr. Sulloway, who was not involved in the study but wrote an editorial accompanying it, added that “there was some room for doubt about this effect before, but that room has now been eliminated.”
Effects of birth order are notoriously difficult to study, and some critics are still dubious. Joseph Lee Rodgers, a psychologist at the
University of Oklahoma and a longtime skeptic of such effects, said the new analysis was not conclusive.
“Past research included hundreds of reported birth order effects” that were not legitimate, Dr. Rodgers wrote in an e-mail message. “I’m not sure whether the patterns in the Science article are real or not; more description of methodology is required.”
In the study, Norwegian epidemiologists analyzed data on birth order, health status and I.Q. scores of 241,310 18- and 19-year-old men born from 1967 to 1976, using military records. After correcting for factors that may affect scores, including parents’ education level, maternal age at birth and family size, the researchers found that eldest children scored an average of 103.2, about 3 percent higher than second children (100.3) and 4 percent higher than thirdborns (99.0).
The difference was an average, meaning that it varied by family and showed up in most families but not all.
The scientists then looked at I.Q. scores in 63,951 pairs of brothers, and found the same results. Differences in household environments did not explain elder siblings’ higher scores.
Because sex has little effect on I.Q. scores, the results almost certainly apply to females as well, said Dr. Petter Kristensen, an epidemiologist at the University of Oslo and the lead author of the Science study. His co-author was Dr. Tor Bjerkedal, an epidemiologist at the Norwegian Armed Forces Medical Services.
To test whether the difference could be due to biological factors, the researchers examined the scores of young men who became the eldest in the household after an older sibling had died. Their scores came out the same, on average, as those of biological firstborns.
“This is quite firm evidence that the biological explanation is not true,” Dr. Kristensen said in a telephone interview.

Social scientists have proposed several theories to explain how birth order might affect intelligence scores. Firstborns have their parents’ undivided attention as infants, and even if that attention is later divided evenly with a sibling or more, it means that over time they will have more cumulative adult attention, in theory enriching their vocabulary and reasoning abilities.
But this argument does not explain a consistent finding in children under 12: among these youngsters, later-born siblings actually tend to outscore the eldest on I.Q. tests. Researchers theorize that this precociousness may reflect how new children alter the family’s overall intellectual resource pool.
Adding a young child may, in a sense, diminish the family’s overall intellectual environment, as far as an older sibling is concerned; yet the younger sibling benefits from the maturity of both the parents and the older brother or sister. This dynamic may quickly cancel and reverse the head start the older child received from his parents.
Still, the question remains: How do the elders sneak back to the head of the class?
One possibility, proposed by the psychologist Robert Zajonc, is that older siblings consolidate and organize their knowledge in their natural roles as tutors to junior. These lessons, in short, benefit the teacher more than the student.
Another potential explanation concerns how siblings find a niche in the family. Some studies find that both the older and younger siblings tend to describe the firstborn as more disciplined, responsible, high-achieving. Studies suggest — and parents know from experience — that to distinguish themselves, younger siblings often develop other skills, like social charm, a good curveball, mastery of the electric bass, acting skills.
“Like Darwin’s finches, they are eking out alternative ways of deriving the maximum benefit out of the environment, and not directly competing for the same resources as the eldest,” Dr. Sulloway said. “They are developing diverse interests and expertise that the I.Q. tests do not measure.”
This kind of experimentation might explain evidence that younger siblings often live more adventurous lives than their older brother or sister. They are more likely to participate in dangerous sports than eldest children, and more likely to travel to exotic places, studies find. They tend to be less conventional than firstborns, and some of the most provocative and influential figures in science spent their childhoods in the shadow of an older brother or sister (or two or three or four).
Charles Darwin, author of the revolutionary “Origin of Species,” was the fifth of six children. Nicolaus Copernicus, the Polish-born astronomer who determined that the sun, not the earth, was the center of the planetary system, grew up the youngest of four. The mathematician and philosopher René Descartes, the youngest of three, was a key figure in the scientific revolution that began in the
16th century.
Firstborns have won more Nobel Prizes in science than younger siblings, but often by advancing current understanding, rather than overturning it.
“It’s the difference between every-year or every-decade creativity and every-century creativity,” Dr. Sulloway said, “between innovation and radical innovation.”

You will have 15 minutes to answer the before you read questions, 10 minutes per station, and 20 minutes to answer the after you’ve read questions. This will be collected for a grade!
1.) Based off of what you know about intelligence, do you believe that intelligence can really be measured accurately? What are some possible factors that could influence IQ scores? Justify your responses.
2.) For each of the following, explain in detail how you think these factors impact IQ (negatively, positively, not at all, etc.):
Birth Order:
Environment:
Mother’s lifestyle (dietary or other) during pregnancy:
Structure and size of the brain:
Gender:
Article #1: “Can Intelligence Really Be Measured?”
1.) Do you agree with the academic areas that IQ tests focus on? Why or why not? If not, explain what areas they should focus on instead.
2.) How do you think knowing one’s IQ score could impact a person’s behavior?

Article #2: Intelligence In Men And Women Is A Gray And White Matter
1.) To what extent does gender play a role on intelligence? Be sure to address gray vs. white matter
Article #3: Breastfeeding for longer 'improves child's intelligence'
1.) Draw conclusions on how breast feeding will influence a child’s intelligence; be sure to include specific examples.
Article #4: Is this proof smoking lowers your IQ? Study suggests those on 20 a day are less intelligent
AND Article #5: Maternal smoking during pregnancy and offspring IQ.
1.) Make connections from both articles and explain how personal choices and choices of others’ impact intelligence.
Article #6: Even Moderate Drinking While Pregnant Can Hurt Child's IQ
1.) Some professionals state that women who are pregnant should completely refrain from drinking, while others say that moderately drinking is okay. To what degree should this decision be left open to interpretation?
Article #7: Fact or Fiction: When It Comes to Intelligence, Does Brain Size Matter?
1.) In what ways can the size of one’s brain be controlled, thus leading to the question, to what extent does brain size correlate to intelligence?

Article #8: Study Says Eldest Children Have Higher I.Q.s
1.) Using the information from the article, explain how & why your birth order could be related to your intelligence. If you are an only child, assume that you are the oldest 
1.) Do you believe that the government should have stricter regulations and/or create laws for pregnant women regarding their lifestyle choices? Provide details and examples for your stance.
2.) From the articles you read and from a psychological perspective, do you believe that it is possible to take control of one’s own destiny? In your opinion what does this idea mean?
3.) Explain which articles relate to the nature side of intelligence and which ones relate to nurture; justify your response.