漢譯英

基因和行為：雙重遺傳生物學因素

或許并不能決定人的命運，但是基因對人類行為的影響顯然比人們普遍認為的要大得多。很多自出生后便被分開的孿生子身上呈現出各種相似點，包括恐懼感、業余愛好、身體語言等。心理學家小托馬斯.J.布恰德說，許多此類行為都是“那些打算研究行為遺傳學的人根本就不會想到要去留意的”。他是明尼蘇達大學孿生與收養研究中心的主任。

布恰德稱，到目前為止，他們已經完成了詳盡的心理測試和問卷調查，研究對象包括約50對被分開撫養的同卵孿生子，25對被分開撫養的異卵孿生子，以及由若干對一同長大的孿生子組成的對照組。布恰德說：“孿生子在姿態和表達風格上的相似令我們感到驚訝。這或許是該項研究最令我們著迷的特點。”孿生子往往擁有相似的癖好、姿勢、說話的速度和節奏、習慣以及慣常講的笑話。

許多孿生子有著相似的穿著風格。一對從未見過面的孿生兄弟來到了英國，他們蓄著相同的胡須，梳著相同的發型，帶著相同的金絲邊眼鏡，穿著相同的襯衫。還有一對孿生子的洗漱用品幾乎完全一樣，包括同一個牌子的科隆香水和某種瑞典品牌的牙膏。

盡管許多被分開撫養的孿生子有著不同的職業和教育程度，但是調查者一再發現他們在興趣愛好方面的相似點。有一對孿生子都是志愿消防隊員，有一對都是副行政司法長官，有一對孿生兄弟在各自的地下室中有著相似的工作間，還有一對孿生姐妹的廚房布置驚人地相似。

在變態行為或精神病理學方面，布恰德還沒有掌握足夠的信息用于歸納總結，但是他已經發現了反復呈現的類似點。有一對孿生姐妹都很迷信;另一對只要受到最輕微的刺激就會落淚，經詢問，她倆從小就都是這樣。“她倆一同參加了一個聊天節目，在被問及其中一個問題的時候，兩人同時哭了起來。”布恰德說。

然而，最驚人的普通精神病理學案例卻來自一對被分開撫養的異卵孿生子。其中一個是由其貧窮的親生父母養大的，另外一個被一戶殷實的中上階層家庭所收養。現在，這兩個人都被認為具有反社會的個性，他們缺少控制沖動的能力，而且都有犯罪史。雖然異卵孿生子平均擁有50 010的相同基因，但是布恰德認為在這對孿生子身上相同基因的數量或許要高得多。

明尼蘇達大學心理學家奧克·特立根進行的測試表明，對于被分開撫養的同卵孿生子來說，其個性的相似點幾乎跟一同長大的同卵孿生子一樣廣泛。他的個性調查問卷列出了“社交親近度”、“傷害逃避”和“幸福感”等不同的尺度。尤其令研究者感到吃驚的，是發現“傳統主義”這種意味著保守和尊重權威的性格竟然也可以遺傳。布恰德說，事實上，通過他和別人的研究，已經發現了有大約11種性格特征似乎深受遺傳的影響。

總的來說，明尼蘇達州的研究者的發現對那些認為環境是性格的根本塑造者的人們提出了有力的反駁。布恰德預言，教科書恐怕得重新書寫了。

如今世界很多地方的人們都有充足的食物，生存繁殖比以往任何時候都更為容易，所以很容易以為人類已經停止了進化。但是一項頗具爭議的新研究結果卻不這么認為。據其分析，人類的進化速度非但不曾放緩，相反，在過去4萬年里加快了速度，過去5000年更是加快了100倍。這意味著盡管有些人游走異鄉，與異族人通婚，但各大洲大多數人正在變得越來越不同，他們的基因并沒有越來越同質化。

1800個人類基因已加快了進化，占人類基因組的7%。大多數基因突變都因人口猛增而產生。人口增長時，基因突變也會增加，這就提升了產生有益的基因變體的機會，這種有益的基因變體將提升人類的生存能力，并在整個人群中傳播(這和大群昆蟲制造抗殺蟲劑的基因的速度比小群快是同樣道理)。

研究人員沒有破譯大部分進化的基因，但他們說其中很多似乎都是應對人類飲食變化，和人類農墾初期曾肆虐過的中毒疾病卷土重來的結果。有些基因突變使成人能夠消化淀粉、脂肪酸和牛奶中的乳糖。還有些增強了人類抵御瘧疾、愛滋病和黃熱病等疾病的能力。

參考譯文

Genes and Behavior: A Twin Legacy

Biology may not be destiny, but genes apparently have a far greater influence on human behavior than is commonly thought. Similarities ranging from phobias to hobbies to bodily gestures are being found in pairs of twins separated at birth. Many of these behaviors are "things you would never think of looking at if you were going to study the genetics of behavior," says psychologist Thomas J. Bouchard, Jr., director of the Minnesota Center for Twin and Adoption Research at the University of Minnesota.

Bouchard reports that so far, exhaustive psychological tests and questionnaires have been completed with approximately 50 pairs of identical twins reared apart, 25 pairs of fraternal twins reared apart and comparison groups of twins reared together. "We were amazed at the similarity in posture and expressive style," says Bouchard. "It's probably the feature of the study that's grabbed us the most." Twins tend to have similar mannerisms, gestures, speed and tempo in talking, habits, and jokes.

Many of the twins dressed in similar fashion - one male pair who had never previously met arrived in England sporting identical beards, haircuts, wire-rimmed glasses and shirts. One pair had practically the same items in their toilet cases, including the same brand of cologne and a Swedish brand of toothpaste.

Although many of the separated pairs had differing types of jobs and educational levels, the investigators are finding repeated similarities in hobbies and interests - one pair were both volunteer firefighters, one pair were deputy sheriffs, a male pair had similar workshops in their basements and a female pair had strikingly similar kitchen arrangements.

Bouchard doesn't have enough information on abnormal behavior or psychopathology to make generalizations, but he has found repeated similarities. One pair of women were both very superstitious; another pair would burst into tears at the drop of a hat, and questioning revealed that both had done so since childhood. "They were on a talk show together and both started crying in response to one of the questions," says Bouchard.

The most striking example of common psychopathology, however, came from a pair of fraternal twins reared apart. One had been reared by his own poor family; the other had been adopted into a "good solid upper - middle-class family." Both are now considered to be antisocial personalities, suffering from lack of impulse control, and both have criminal histories. Although fraternal twins share, on average, 50 percent of their genes, Bouchard suggests that the overlap is probably considerably more with this pair.

Personality similarities between the identical twins reared apart are almost as pervasive as they are with identical twins reared together, according to the results of a test developed by University of Minnesota psychologist Auke Tellegen. His personality questionnaire contains scales such as "social closeness", " harm avoidance" and "well-being". The researchers were especially surprised to find that "traditionalism" - a trait implying conservatism and respect for authority - can be inherited. In fact, says Bouchard, his and other studies have found about 11 personality traits that appear to have significant genetic input.

Overall the emerging findings of the Minnesota study constitute a powerful rebuttal to those who maintain that environmental influences are the primary shaping forces of personality. The textbooks are going to have to be rewritten, Bouchard predicts.

Plentiful food has made it easier than ever before to survive and reproduce in many parts of the world, so it's tempting to think that our species has stopped evolving. But a controversial new study says that isn't so .Far from slowing down, human evolution has sped up in the past 40,000 years and has become 100 times faster in the past 5,000 years alone, according to the analysis. This means that even though some people have been globe-trotters who interbreed, most humans on different continents are becoming more different, rather than blending together into one genetically homogenous race.

Evolution has accelerated in 1800 human genes, which encompass about 70/o of the human genome. Most of the mutations resulted from dramatic population booms. As populations expand, the number of mutations increases, boosting the chances for a beneficial genetic variant that can improve survival and sweep through a population (in the same way that a large population of insects develops a gene for resistance to a pesticide faster than a small population).

Although the researchers don't know the identity of most of the genes, they say quite a few appear to be responses to changes in diet and a new wave of virulent diseases that swept through human populations as they began farming. Some mutations allow adults to digest starch, fatty acids, and lactose in milk. Others improve the resistance to diseases, such as malaria, AIDS, and yellow fever.