Height and intelligence
Encyclopedia
Height
and intelligence
research
investigates the relationship between height and intelligence.
and young adults indicate a very small positive correlation
between human IQ
and height within national populations. The association is supported by studies linking height at eighteen with subsequent scholarly performance.
Correlation coefficients in developing children are typically about 0.2, meaning that variation in height explains about 4% of the variation in IQ.
A large study conducted on Norwegian soldiers the correlation between height and general ability was .15, (meaning it predicts 2.25% of intelligence). The effect appears to hold into the extremes of stature, but may decrease with age.
The correlation between the two factors is therefore weak, although statistically significant. Consequently, these studies do not imply that there are no short people who are highly intelligent or that variations in stature have a direct effect on cognitive ability. However, similar strength correlations have been found in early and late childhood in both developed and developing countries, even after controlling for social class
and parental education. In adults, changes in environment and social status reduce the strength of this correlation.
A recent study by Anne Case and Christina Paxson
has attracted media attention.
It has been suggested that the large increases in average height, assumed to be due to improved nutrition, have been accompanied by an increase in brain size which may be one explanation for the Flynn effect
.
Studies have shown however, that common genetic factors
influence variation in both height and intelligence, and are responsible for some of the effect, or that both height and intelligence may be affected by adverse early environmental exposures. Two large recent twin pair studies
of the height-intelligence relationship showed that both shared environment (59% in both studies) and shared genetics (35% in one study and 31% in the other) are responsible for significant portions of the observed correlation between intelligence and height.
Human height
Human height is the distance from the bottom of the feet to the top of the head in a human body standing erect.When populations share genetic background and environmental factors, average height is frequently characteristic within the group...
and intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
research
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
investigates the relationship between height and intelligence.
Correlation
Studies of developing adolescentsand young adults indicate a very small positive correlation
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
between human IQ
Intelligence quotient
An intelligence quotient, or IQ, is a score derived from one of several different standardized tests designed to assess intelligence. When modern IQ tests are constructed, the mean score within an age group is set to 100 and the standard deviation to 15...
and height within national populations. The association is supported by studies linking height at eighteen with subsequent scholarly performance.
Correlation coefficients in developing children are typically about 0.2, meaning that variation in height explains about 4% of the variation in IQ.
A large study conducted on Norwegian soldiers the correlation between height and general ability was .15, (meaning it predicts 2.25% of intelligence). The effect appears to hold into the extremes of stature, but may decrease with age.
The correlation between the two factors is therefore weak, although statistically significant. Consequently, these studies do not imply that there are no short people who are highly intelligent or that variations in stature have a direct effect on cognitive ability. However, similar strength correlations have been found in early and late childhood in both developed and developing countries, even after controlling for social class
Social class
Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...
and parental education. In adults, changes in environment and social status reduce the strength of this correlation.
A recent study by Anne Case and Christina Paxson
has attracted media attention.
Explanations of the correlation
The reasons for the association between height and intelligence remain unclear, but possible explanations include that height may be a marker of nutritional status, prenatal maternal stress, or general mental and physical health during development. As brain size correlates 0.40 with IQ, height/IQ correlation could be merely a side product of taller people having larger heads and thus larger brains. It should be noted, however, that head size - as opposed to brain size - correlates 0.20 with intelligence.It has been suggested that the large increases in average height, assumed to be due to improved nutrition, have been accompanied by an increase in brain size which may be one explanation for the Flynn effect
Flynn effect
The Flynn effect is the name given to a substantial and long-sustained increase in intelligence test scores measured in many parts of the world. When intelligence quotient tests are initially standardized using a sample of test-takers, by convention the average of the test results is set to 100...
.
Studies have shown however, that common genetic factors
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
influence variation in both height and intelligence, and are responsible for some of the effect, or that both height and intelligence may be affected by adverse early environmental exposures. Two large recent twin pair studies
Twin study
Twin studies help disentangle the relative importance of environmental and genetic influences on individual traits and behaviors. Twin research is considered a key tool in behavioral genetics and related fields...
of the height-intelligence relationship showed that both shared environment (59% in both studies) and shared genetics (35% in one study and 31% in the other) are responsible for significant portions of the observed correlation between intelligence and height.