Iq And Behavioral Genetics example essay topic

Human Behavior Genetics To illustrate a point concerning the inheritance of gestures, Charles Darwin quoted an interesting case that had been brought to his attention by Galton. A gentleman of considerable position was found by his wife to have the curious trick, when he lay fast asleep on his back in bed, of raising his right arm slowly in front of his face, up to his forehead, and then dropping it with a jerk so that the wrist fell heavily on the bridge of this nose. The trick did not occur every night but occasionally. Many years after his death, his son married a lady who had never heard of the family incident. She, however, observed precisely the same peculiarity in her husband... One of his children, a girl, has inherited the same trick.

(Darwin, 1872: 33-34) Probably everyone could cite some examples, perhaps not as quaint as Gallons, in which some peculiarity of gait, quality of temper, degree of talent, or other trait is characteristic of a family, and such phrases as a chip off the old block, like father, like son, and it runs in the family give ample evidence of the general acceptance of the idea that behavioral traits may be inherited, as are physical ones. Discussion What Is Behavioral Genetics: Behavioral genetics is simply the intersection between genetics and the behavioral sciences. Behavioral geneticists are currently applying the various techniques of genetic analysis to various behavioral characters in order to learn more about them. The characters under study are diverse, varying in subject from homosexuality, IQ, and even hostility. Homosexuality: Many theories have been presented to explain homosexuality behavior in humans. Two of these such theories are E. Slaters Birth order and maternal ag of homosexuals theory and hormonal differences.

Birth Order and Maternal Age of Homosexuals: E. Slaters studies in homosexuality led him to the finding that male homosexuals tend to be born late in sibling order. He found an increase in mean birth order, and increase in maternal age at birth, and a variance of maternal age as great as that of patients with Downs syndrome (mongolism) This increase approached the figure obtained in the small series of Turners and Klinefelters cases in the literature and differed widely from that of the general population. Slater regarded these findings as supporting a hypotheses of heterogeneity in the etiology of homosexuality in the male and as suggesting that a chromosomal anomaly such as might be associated with late maternal age may play a part in causation in some instances. To be sure, this information was re investigated and found that a shift in paternal age was primary; this finding would rule out a chromosomal theory and suggest a genetically predisposition to sexual deviance manifesting in the fathers (Kaplan, 1976: 301-304). Hormonal Differences: Another theory on the subject of homosexuality deals with hormonal differences in adult homosexuals.

Low urinary testosterone levels have been noted in male homosexuals and, likewise, female homosexuals have been reported as excreting low levels of estrogen. IQ and Behavioral Genetics: Human intelligence can be usefully construed as a single trait which is largely under genetic control. The influence of different genetic and environmental factors have been estimated, but only crudely. A study of foster children by S kodak and S keels showed that both the rate of increasing resemblance to true parents and the final level achieved is the same regardless of whether children are raised by their true parents or not. This is extremely strong evidence in support of genetic control of intelligence. However, that same study also revealed evidence that the childrens IQ levels were in fact, higher on average than the mothers.

These differences can be attributed to adoption (Barker, 1995: 74-79). There is interesting evidence that societies which reward on the basis of individual ability are becoming stratified in such a way that differences in intelligence have a genetic component. Earlier studies of family size and IQ led to the prediction of a decline in the intelligence of the populations studied. These predictors were shown to be due to an error, and natural selection for IQ was shown to be positive in the same populations. Nevertheless, the relationship is a dynamic one, changing with different social conditions, and it should be a topic of constant scrutiny (Barker, 1995: 74-79). Alcoholism: Alcoholism, regarded by the early eugenicists as part of a syndrome of hereditary degeneration including also criminality, insanity, and epilepsy, has remained a social issue of great importance.

Indeed, alcoholism is one of the principal public health problems in the United States today, with estimates of the number of those dependent upon alcohol in the country ranging as high as 10 million. The tendency for alcoholism to run in families has been long noted in folklore, and is upheld by a number of investigations into the distribution of alcoholism within families. A particularly extensive investigation was made by A mark, who studied several large samples of alcoholics and their relatives in the Swedish population. One feature of this study is particularly clear. The incidence of the condition is higher in males than in females, and is also higher among relatives of pro bands than in the population at large (Ehrman, 1976: 285-291). Antisocial Behavior: Within the last several decades, a specific sex-chromosome anomaly in phenotypic males has received considerable publicity.

In 1965, Jacobs and so-workers reported that the incidence of chromosomal anomalies among individuals institutionalized because of dangerous, violent, or criminal behavior was higher than that in the population at large. Of 197 institutionalized volunteers who were karyotype d, 12 were found to have a chromosomal anomaly of some kind. One was a 46, XY/47, XXY mosaic, one as 48, XYY, and seven were 47, XYY. Three had no sex-chromosome differences, but only minor autosomal defects. The average height of the 47, XXY males was 73 inches, in contrast to an average height of 67 inches for the males of normal karyotypes in the institution (Dawkins, 1973: 301-304). The possibility of a genetic component in criminality has raised a number of interesting legal problems.

In 1968, the defense attorney for a man on trial for murder in Paris presented an unusual defense. He claimed that his client possessed an extra Y chromosome and, thus, was not criminally responsible for this act. Although convicted, a reduced sentence was imposed. At about the same time in Australia, a jury acquitted a man charged with murder on the grounds of legal insanity after a defense witness testified that the man had an extra Y chromosome.

As it stands, there now appears to be some precedent for diminished responsibility before the law of XYY individuals (McC learn, 1973: 301-304). Conclusions Although history has long attributed some actions to like father, like son or it runs in the family, the quickly expanding field of behavioral genetics is finally offering some proof to those claims. After determining the cause of starting point of such problems as alcoholism, sleep problems, schizophrenia, and certain types of antisocial behavior, the field of behavioral genetics may begin to shed some light upon possible solutions with the use of genetic engineering for eliminating these problems. The only remaining thought would be whether or not we have the right to start eliminating and changing human characteristics.