Intelligence is the key to success in a competitive environment. Parents watch the activities of their children in their formative years. They proudly tell others how intelligently their children do certain things when they are left to their own devices or are interacting with others. Intelligence is a human faculty that distinguishes humans from lower animals. Scientists have devised techniques to measure the level of intelligence of people for choosing their abilities for doing certain jobs. Standard tests have been designed that quantify the level of intelligence a person possesses and put a figure on every person undergoing these tests. There are critiques of this method, too. They argue that human intelligence is not linear and that a particular kind of test can give an idea about only one side of a person's intellect. The American psychologist Howard Gardner came up with such a theory to incorporate different traits of a person's intelligence. Encarta gives the following accounts of people's IQ tests based on the assumption that there are separate spots in a human brain that are dedicated to different kinds of intellectual activities:
"Gardner argued that we do not have one underlying general intelligence, but instead have multiple intelligences, each part of an independent system in the brain.
In formulating his theory, Gardner placed less emphasis on explaining the results of mental tests than on accounting for the range of human abilities that exist across cultures. He drew on diverse sources of evidence to determine the number of intelligences in his theory. For example, he examined studies of brain-damaged people who had lost one ability, such as spatial thinking, but retained another, such as language. The fact that two abilities could operate independently of one another suggested the existence of separate intelligences. Gardner also proposed that evidence for multiple intelligences came from prodigies and savants. Prodigies are individuals who show an exceptional talent in a specific area at a young age, but who are normal in other respects. Savants are people who score low on IQ tests-and who may have only limited language or social skills-but demonstrate some remarkable ability, such as extraordinary memory or drawing ability. To Gardner, the presence of certain high-level abilities in the absence of other abilities also suggested the existence of multiple intelligences.
Gardner initially identified seven intelligences and proposed a person who exemplified each one. Linguistic intelligence involves aptitude with speech and language and is exemplified by poet T. S. Eliot. Logical-mathematical intelligence involves the ability to reason abstractly and solve mathematical and logical problems. Physicist Albert Einstein is a good example of this intelligence. Spatial intelligence is used to perceive visual and spatial information and to conceptualize the world in tasks like navigation and in art. Painter Pablo Picasso represents a person of high spatial intelligence. Musical intelligence, the ability to perform and appreciate music, is represented by composer Igor Stravinsky. Bodily-kinesthetic intelligence is the ability to use one's body or portions of it in various activities, such as dancing, athletics, acting, surgery, and magic. Martha Graham, the famous dancer and choreographer, is a good example of bodily-kinesthetic intelligence. Interpersonal intelligence involves understanding others and acting on that understanding and is exemplified by psychiatrist Sigmund Freud. Intrapersonal intelligence is the ability to understand one's self and is typified by the leader Mohandas Gandhi. In the late 1990s Gardner added an eighth intelligence to his theory: naturalist intelligence, the ability to recognize and classify plants, animals, and minerals. Naturalist Charles Darwin is an example of this intelligence. According to Gardner, each person has a unique profile of these intelligences, with strengths in some areas and weaknesses in others.
Gardner's theory found rapid acceptance among educators because it suggests a wider goal than traditional education has adopted. The theory implies that traditional school training may neglect a large portion of human abilities, and that students considered slow by conventional academic measures might excel in other respects. A number of schools have formed with curricula designed to assess and develop students' abilities in all of the intelligences Gardner identified".
Heredity, environment and intelligence
Is there a correlation between intelligence and heredity? The question is not new. Even in antiquity such questions were raised by scientists and philosophers. Eugenics was such a scientific proposition that attempted to classify people's merit according to their ancestral and racial lineage. The proponents of eugenics did not consider the influence of environmental factors in the development of human intellect. Moreover, such an attempt to discriminate people based on their familial backgrounds created a lot of controversy among the intellectual circles. Encarta has again the following to say:
"Is intelligence determined primarily by heredity or by one's environment?
The issue has aroused intense debate because different views on the heritability of intelligence lead to different social and political implications. The strictest adherents of a genetic view of intelligence believe that every person is born with a fixed amount of intelligence. They argue that there is little one can do to improve intelligence, so special education programs should not be expected to produce increases in IQ. On the other hand, those who see intelligence as determined mostly by environmental factors see early intervention programs as critical to compensate for the effects of poverty and other disadvantages. In their view, these programs help to create equal opportunities for all people. Perhaps the most controversial issue surrounding intelligence has been the assertion by some people that genetic factors are responsible not only for differences in IQ between individuals, but also for differences between groups. In this view, genetic factors account for the poorer average performance of certain racial and ethnic groups on IQ tests. Others regard genetic explanations for group differences as scientifically indefensible and view as racist the implication that some racial groups are innately less intelligent than others.
Today, almost all scientists agree that intelligence arises from the influence of both genetic and environmental factors. Careful study is required in order to attribute any influence to either environment or heredity. For example, one measure commonly used to assess a child's home environment is the number of books in the home. But having many books in the home may be related to the parents' IQ, because highly intelligent people tend to read more. The child's intelligence may be due to the parents' genes or to the number of books in the home. Further, parents may buy more books in response to their child's genetically influenced intelligence. Which of these possibilities is correct cannot be determined without thorough studies of all the factors involved.
In behavioural genetics, the heritability of a trait refers to the proportion of the trait's variation within a population that is attributable to genetics. The heritability of intelligence is usually defined as the proportion of the variation in IQ scores that is linked to genetic factors. To estimate the heritability of intelligence, scientists compare the IQs of individuals who have differing degrees of genetic relationship. Scientists have conducted hundreds of studies, involving tens of thousands of participants, that have sought to measure the heritability of intelligence. The generally accepted conclusion from these studies is that genetic factors account for 40 to 80 percent of the variability in intelligence test scores, with most experts settling on a figure of approximately 50 percent. But heritability estimates apply only to populations and not to individuals. Therefore, one can never say what percentage of a specific individual's intelligence is inherited based on group heritabilities alone.
Although any degree of genetic relationship can and has been studied, studies of twins are particularly informative. Identical twins develop from one egg and are genetically identical to each other. Fraternal twins develop from separate eggs and, like ordinary siblings, have only about half of their genes in common. Comparisons between identical and fraternal twins can be very useful in determining heritability. Scientists have found that the IQ scores of identical twins raised together are remarkably similar to each other, while those of fraternal twins are less similar to each other. This finding suggests a genetic influence in intelligence. Interestingly, fraternal twins' IQ scores are more similar to each other than those of ordinary siblings, a finding that suggests environmental effects. Some researchers account for the difference by noting that fraternal twins are probably treated more alike than ordinary siblings because they are the same age.
Some of the strongest evidence for genetic influences in intelligence comes from studies of identical twins adopted into different homes early in life and thus raised in different environments. Identical twins are genetically identical, so any differences in their IQ scores must be due entirely to environmental differences and any similarities must be due to genetics. Results from these studies indicate that the IQ scores of identical twins raised apart are highly similar-nearly as similar as those of identical twins raised together. For adoption studies to be valid, placement of twin pairs must be random. If brighter twin pairs are selectively placed in the homes of adoptive parents with higher intelligence, it becomes impossible to separate genetic and environmental influences".