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In the angry debate over how much of IQ comes from the genes that children inherit from parents and how much comes from experiences, one little fact gets overlooked: no one has identified any genes (other than those that cause retardation) that affect intelligence. So researchers led by Robert Plomin of London"s Institute of Psychiatry decided to look for some: Plomin"s colleagues drew blood from two groups of 51 children each. They are all White living in six counties around Cleveland. In one group, the average IQ is 136. In the other group, the average IQ is 103. Isolating the blood cells, the researchers then examined each child"s chromosome 6 (One of the 23 human chromosomes). Of the 37 land marks on chromosome 6 that the researchers looked for, one jumped out: a form of gene called IGF2R occurred in twice as many children in high IQ group as in the average growth—32 percent versus 16 percent. The study concludes that it is this form of the IGF2R gene, called allele 5, that contributes to intelligence. Plomin cautions that "This is not a genius gene. It is one of many". (About half the differences in intelligence between one person and another are thought to reflect different genes, and half reflect different life experiences.)The gene accounts for no more than four extra IQ points. And it is neither necessary nor sufficient for high IQ: 23 percent of the average-IQ kids did have it, but 54 percent of genius kids did not. The smart gene is known by the snappy name "insulin like growth factor 2 receptor" (IGH2R to its fun). It lets hormones like one similar to insulin dock with cells. Although a gene involved with insulin is not the most obvious candidate for an IQ gene, new evidence suggests it might indeed play the role. Sometimes when s hormone docks with the cell, it makes the cell grow; sometimes it makes the cell commit suicide. Both responses could choreograph the development of the brain. Scientists at the National Institutes of Health find that insulin can stimulate nerves to grow. And in rat brains, regions involved in learning and memory are chock full of insulin receptors. Even though this supports the idea that IGF2R can affect the brain and hence intelligence, some geneticists see major problems with the IQ-gene study. One is the possibility that Plomin"s group fell for what"s called the chopsticks fallacy. Geneticists might think they"ve found a gene for chopsticks dexterity, but all they"ve really found is a gene more common in Asians than, say, Africans. Similarly, Plomin"s IQ gene might simply be one that is more common in groups that emphasize academic achievement. "What if the gene they"ve found reflects ethnicity" asks geneticist Andrew Feinberg of Johns Hopkins University. "I would take these findings with a whole box of salt". It is found that insulin______.
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Your eye is a window on the nerves and blood vessels, revealing vital information about your entire body. An (1)_____ exam starts from the outside and works in. First the ophthalmologist(眼科医生) gauges (2)_____ with the familiar wall chart and checks visual field by moving objects in and out of (3)_____. A limited visual field could be the (4)_____ of the high inner eye pressure of glaucoma(青光眼)or (5)_____ a tumor pressing on nerves leading from the eye. The physician also checks for infection around the lashes and notes how fast the lids follow the eyes downward. Lid lag sometimes (6)_____ thyroid disease(甲状腺疾病). If one pupil contracts (7)_____ the other doesn"t, the physician is (8)_____ to the fact that (9)_____ a tumor or stroke, perhaps, has damaged the nerves between the eye and brain. A tumor as far away (10)_____ the lung can cause capillary problems by hitting a nerve that loops through the neck. The white of the eye, tear ducts, lens and retina(视网膜) are checked for (11)_____ of trouble. Too many white blood cells (12)_____ inflammation, blood means tissue has tom or a vessel has burst, and deposits of (13)_____ material can mean eye disease. The orange-red retina holds many more (14)_____ for disease detection. High blood pressure may announce its (15)_____ by pushing the vessels off track at their intersections. (16)_____ vessel growth is a sign of diabetic retinopathy(糖尿病性视网膜病). Narrowed vessels may indicate (17)_____ of the arteries, and damage to tiny capillaries could be a sign of early diabetes. The doctor even examines the pin-head-size hole in the back of the optic nerve on their way to the brain. (18)_____ the appearance of these nerve fibers is abnormal, nerve tissue may have been damaged because of intraocular pressure, indicating glaucoma or the presence of a tumor. When a physician needs quick, (19)_____ information about the body, the eyes have (20)_____.
Your eye is a window on the nerves and blood vessels, revealing vital information about your entire body. An (1)_____ exam starts from the outside and works in. First the ophthalmologist(眼科医生) gauges (2)_____ with the familiar wall chart and checks visual field by moving objects in and out of (3)_____. A limited visual field could be the (4)_____ of the high inner eye pressure of glaucoma(青光眼)or (5)_____ a tumor pressing on nerves leading from the eye. The physician also checks for infection around the lashes and notes how fast the lids follow the eyes downward. Lid lag sometimes (6)_____ thyroid disease(甲状腺疾病). If one pupil contracts (7)_____ the other doesn"t, the physician is (8)_____ to the fact that (9)_____ a tumor or stroke, perhaps, has damaged the nerves between the eye and brain. A tumor as far away (10)_____ the lung can cause capillary problems by hitting a nerve that loops through the neck. The white of the eye, tear ducts, lens and retina(视网膜) are checked for (11)_____ of trouble. Too many white blood cells (12)_____ inflammation, blood means tissue has tom or a vessel has burst, and deposits of (13)_____ material can mean eye disease. The orange-red retina holds many more (14)_____ for disease detection. High blood pressure may announce its (15)_____ by pushing the vessels off track at their intersections. (16)_____ vessel growth is a sign of diabetic retinopathy(糖尿病性视网膜病). Narrowed vessels may indicate (17)_____ of the arteries, and damage to tiny capillaries could be a sign of early diabetes. The doctor even examines the pin-head-size hole in the back of the optic nerve on their way to the brain. (18)_____ the appearance of these nerve fibers is abnormal, nerve tissue may have been damaged because of intraocular pressure, indicating glaucoma or the presence of a tumor. When a physician needs quick, (19)_____ information about the body, the eyes have (20)_____.
In the angry debate over how much of IQ comes from the genes that children inherit from parents and how much comes from experiences, one little fact gets overlooked: no one has identified any genes (other than those that cause retardation) that affect intelligence. So researchers led by Robert Plomin of London"s Institute of Psychiatry decided to look for some: Plomin"s colleagues drew blood from two groups of 51 children each. They are all White living in six counties around Cleveland. In one group, the average IQ is 136. In the other group, the average IQ is 103. Isolating the blood cells, the researchers then examined each child"s chromosome 6 (One of the 23 human chromosomes). Of the 37 land marks on chromosome 6 that the researchers looked for, one jumped out: a form of gene called IGF2R occurred in twice as many children in high IQ group as in the average growth—32 percent versus 16 percent. The study concludes that it is this form of the IGF2R gene, called allele 5, that contributes to intelligence. Plomin cautions that "This is not a genius gene. It is one of many". (About half the differences in intelligence between one person and another are thought to reflect different genes, and half reflect different life experiences.)The gene accounts for no more than four extra IQ points. And it is neither necessary nor sufficient for high IQ: 23 percent of the average-IQ kids did have it, but 54 percent of genius kids did not. The smart gene is known by the snappy name "insulin like growth factor 2 receptor" (IGH2R to its fun). It lets hormones like one similar to insulin dock with cells. Although a gene involved with insulin is not the most obvious candidate for an IQ gene, new evidence suggests it might indeed play the role. Sometimes when s hormone docks with the cell, it makes the cell grow; sometimes it makes the cell commit suicide. Both responses could choreograph the development of the brain. Scientists at the National Institutes of Health find that insulin can stimulate nerves to grow. And in rat brains, regions involved in learning and memory are chock full of insulin receptors. Even though this supports the idea that IGF2R can affect the brain and hence intelligence, some geneticists see major problems with the IQ-gene study. One is the possibility that Plomin"s group fell for what"s called the chopsticks fallacy. Geneticists might think they"ve found a gene for chopsticks dexterity, but all they"ve really found is a gene more common in Asians than, say, Africans. Similarly, Plomin"s IQ gene might simply be one that is more common in groups that emphasize academic achievement. "What if the gene they"ve found reflects ethnicity" asks geneticist Andrew Feinberg of Johns Hopkins University. "I would take these findings with a whole box of salt". Some geneticists don"t accept the IGF2R gene-study because______.
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