爱思英语编者按:在这个世界上,对于一些人来说,玻璃杯里的水似乎总是半满。对于另外一些人来说,玻璃杯里的水总是半空。但是乐观者是如何首先获得这种积极向上的天性的呢?这是个很有趣的问题。

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Optimism, it seems, is in the genes

FOR some people in this world, the glass always seems to be half-full. For others it is half-empty. But how someone comes to have a sunny disposition in the first place is an interesting question.

It has been known for a long time that optimists see the world selectively, mentally processing positive things while ignoring negative ones, and that this outlook helps determine their health and well-being. In recent years, it has also become clear that carriers of a particular version of a particular gene are at higher risk than others of depression and attempted suicide when they face traumatic events. The gene in question lies in a region of the genome that promotes the activity of a second gene, which encodes a protein called the serotonin transporter. Serotonin is a messenger molecule that carries signals between nerve cells, and it is known to modulate many aspects of human behaviour, although the details are complex and controversial. The transporter protein recycles serotonin back into the cell that produced it, making it available for reuse, but also reducing the amount in the junctions between cells and thus, it is presumed, the strength of the signal.

It has looked increasingly likely, therefore, that genes—particularly those connected with serotonin—have a role to play in shaping a person’s outlook. So Elaine Fox and her colleagues at the University of Essex, in Britain, wondered whether genes play a part in the selective attention to positive or negative material, with consequent effects on outlook.

To find out, they took samples of DNA from about 100 people and then subjected these people to what is known as the dot-probe paradigm test to see how they reacted to different stimuli. In this test participants are briefly shown photographs that may be positive, negative or neutral in tone. They then have to press a keypad to indicate when a dot has appeared on the screen. It has been found by experience that the more distracting an image is, the longer a person takes to respond when the dot appears. That allowed Dr Fox and her team to discover how distracting particular people found particular images.

In a paper just published in the Proceedings of the Royal Society B they report that, sure enough, gene-related variation caused a bias in attention towards positive and negative material. Some people had two “long” versions of the promoter gene (one inherited from each parent), a combination that reduces the amount of serotonin in the junctions between nerve cells. These individuals were biased towards positive images and away from negative ones. By contrast, those who had either a long and a short version of the gene, or two short versions (and thus, presumably, more serotonin in the junctions), did not have such protective biases. In other words, the optimists really did see the world differently.

Rose-tinted spectacles may be good for one’s health, as these results fit in with wider ideas about how a tendency to look on the bright side of life is part of being resilient to stress. Those with short variants of this gene are expected to have an increased susceptibility to mood disorders following such stress. It is not all good news, though, for optimists. Because these results suggest that a person’s attitude to life is inherited, they serve as a stark warning to all buoyant optimists that trying to cheer the rest of the world up with nothing more than a smile and an effortlessly sunny disposition is doomed to failure.

好像乐观取决于基因
 
在这个世界上,对于一些人来说,玻璃杯里的水似乎总是半满。对于另外一些人来说,玻璃杯里的水总是半空。但是乐观者是如何首先获得这种积极向上的天性的呢?这是个很有趣的问题。

长久以来人们知道,乐观者们选择性地看待这个世界,他们的心理处理那些积极的事情但是忽略那些消极的事情,人们还知道这种心态有利于乐观者们的健康和幸福。最近人们还清楚地发现对于有些携带某种特别形式的某种特别基因的人,他们在面对创伤性事件面前更加容易患上抑郁症,也更容易尝试自杀。这种特别的基因位于人类基因组的某个区域,这个区域激活第二种基因,而这第二种基因对所谓的血清素传输子进行蛋白质编码。血清素是一种信使分子,它传输神经细胞间的信号。人们还知道血清素调节人类行为的许多方面,尽管其中的细节很复杂而且对其解释也有争议。传输蛋白把血清素“回收”到产生它的细胞,使其能重复利用,但是这也减少了细胞间的节点数量,因此人们也认为减少了信号的强度。
 
因此,人们越来越发现基因——特别是与血清素相关的基因很可能对人们形成“世界观”有作用。所以来自英国埃塞克斯大学(University of Essex) 的Elaine Fox 和她的同事想知道基因是否在对积极或者消极事件的选择性注意上起一定的作用,从而影响“世界观”。
 
为了找出答案,他们采集了大约100人的DNA样品,然后对这些人进行所谓的点探测任务实验,以便观察他们对不同刺激的反应。在这个实验中,实验参与者们短暂地看一些照片,这些照片的“格调”可能是积极的、消极的或者中性的。然后当这些实验参与者们在屏幕上看到一个点出现后,必须按一下键盘。经验发现照片越是分散人的注意力,那么当点出现在屏幕上后,人们就需要更长的时间做出反应。这就让Fox博士和她的研究小组发现特定的人对特定的照片是如何被吸引的。
 
在刚刚发表于《皇家学会学报B》(Proceedings of the Royal Society B)的文章中,他们报道说,与基因相关的变化肯定导致了人们对积极和消极事物注意力的偏爱。有些人具有两个“长”版本的启动子基因(遗传自双亲),这种组合减少了神经细胞节中血清素的含量。这些人偏爱积极的照片,而不喜欢消极的照片。相反,那些带有一长一短,或者两短“版本”启动子基因的人就没有这种保护性的偏爱,而这种基因组合可能使得神经节中的血清素含量更高。换句话说,乐观者们真地是以不同的方式看世界的。

积极的眼光可能对人的健康有好处,这些结果也和大众的观点相吻合, 那就是经常看到生活阳光的一面会有助于应付压力。而那些“短”版基因的人在这样的压力下可能更易受到情绪混乱的影响。然而,对于乐观者们来说,并非一切都是好消息。因为这些研究结果暗示一个人对待生活的态度可能来自于遗传,这对所有的乐观者们提供了一个严厉的警告:想仅仅依靠微笑和天生的积极性格让整个世界都高兴起来是注定不可行的。