Section C:
Genetics and Environmental Factors in Creating Genius
Dr. Howard Gardner of Harvard University believes that geniuses are largely made. He has banned television from his home because he fears it might ruin the minds of his family. He makes time every day to listen to his seven-year-old son play the piano — even if it is no more than a few minutes during a phone call while he is away at a conference.
Dr. Sandra Scarr of Virginia University(弗吉尼亚大学), president of the Society for Research in Child Development(儿童发展研究会主席), believes geniuses are largely born. She says parents should not worry too much about whether to take their kids to a ball game or to a museum. Talent will out.
It seems experts are as divided as ever over the issue of which is more important, environment or genetics. This may, however, be about to change. A conference organized earlier this year brought to London some of the biggest names from both sides of the debate. Amazing results from unpublished work were revealed — and the beginning of agreement could be perceived.
The most exciting results came from those working on the biology of individual differences. Dr. Robert Plomin of Penn State University(宾夕法尼亚州立大学), hopes to announce within the next few months that he has tracked down one of the genes that plays a part in determining intelligence. A gene has been identified but the results have yet to be confirmed.
At present, it is believed that genes account for at least half of what researchers call "g" — the general thinking ability that IQ tests are supposed to measure — while environmental influences account for the other half. But so far the only evidence for a genetic component has been through statistics, the relationship being inferred mathematically from comparisons of twins and other such studies of close relatives. Plomin's method makes use of new gene mapping techniques and promises to provide direct evidence of the role that genes play.
Plomin stresses that the discovery of a first gene does not mean the puzzle of intelligence has been solved. A single gene will code for only one of the many molecules and cell proteins that are the building blocks of the brain. This means that hundreds, if not thousands, of genes must be involved in intelligence. The identification of even one gene does, however, have immense implications for the genetics/environment debate.
Another advance, a computer-controlled brain scanning device, has led to a second discovery by those seeking the biological component of mental abilities. Professor Camilla Benbow of Iowa State University(爱荷华州立大学) is head of a long-term study of children who are unusually good at math. For many years she has been puzzled as to why so many of the children in her study should be boys — at the top level, there are more boys than girls by a ratio of thirteen to one. In a soon-to-be-published paper, Benbow reveals that the talented boys' brains appear to process information concerning the location of objects in a very different way from those of average boys and even of talented girls.
The brains of children in the study were scanned while being presented with a simple visual puzzle. The boys of average ability and the gifted girls showed strong activity on both sides of their brains as they thought about the puzzle. However, the gifted boys responded very differently. There was a sudden drop in activity in the left side of the brain — the side most involved in language — and an exaggerated reaction on the right, the side strongest at thinking about the location of objects. It seems that the brains of boys with mathematical talent operate in a way that is physically unique.
Benbow says she was surprised that the talented girls should lack this pattern of response. The only explanation she has is that male brains have a tendency to become more divided during development, with different functions located on one side of the brain or the other. When this division is taken to an extreme, unusual mathematical abilities result.
Because females do not have this tendency (this brain division is known to be influenced by male sex chemicals), girls who perform well in mathematics are doing so because they are superior in their overall mental development. And because such all-round ability is less common, this would be the reason for there being fewer mathematically talented girls.
Benbow is quick to add, however, that cultural expectations probably exaggerate the difference. In China, where girls are more likely to get encouragement in mathematics, the number of gifted boys exceeds that of gifted girls by four to one, rather than the thirteen to one seen in the United States.
Both Plomin's and Benbow's findings would seem to give support to the argument that outstanding mental abilities are largely the result of genetics. But the conference heard equally strong evidence for the role that environmental factors play in creating genius. A theme repeatedly heard from the speakers was that special children invariably have special parents.