双语新闻：为什么10%的人是左撇子，而大多数人是右撇子
What do Lady Gaga, Barack Obama, and Bill Gates have in common – aside from their fame? They are all left-handed.
除了名气之外，Lady Gaga、Barack Obama和Bill Gates还有什么共同点？他们都是左撇子。
But why are 10 percent of people left-handed while most are right-handed?
但是为什么10%的人是左撇子，而大多数人是右撇子呢？
Researchers are trying to find out.
研究人员正试图找出答案。
A recent study identified a genetic cause of left-handedness in some people. Researchers found rare variants of a gene involved in controlling the shape of cells. They found the variants to be 2.7 times more common in left-handed people.
最近的一项研究确定了一些人左撇子的遗传原因。研究人员发现了一种罕见的与控制细胞形状有关的基因变体。他们发现这种变体在左撇子中的常见率是前者的2.7倍。
These genetic variants account for possibly 0.1 percent of left-handedness. But the researchers said a gene, called TUBB4B, might play a part in the development of brain asymmetry.
这些基因变异可能占左撇子的0.1%。但研究人员表示，一种名为TUB4B的基因可能在大脑不对称的发展中发挥作用。
In most people, the two halves, or hemispheres, of the brain have slightly different structures and are dominant for different activities.
对大多数人来说，大脑的两半或半球结构略有不同，在不同的活动中占主导地位。
"For example, most people have left-hemisphere dominance for language, and right-hemisphere dominance for tasks that require directing visual attention to a location in space," said Clyde Francks of the Max Planck Institute for Psycholinguistics in the Netherlands. Francks was the top writer of the study published recently in Nature Communications.
荷兰马克斯·普朗克心理语言学研究所的Clyde Francks说：“例如，大多数人在语言方面具有左半球优势，在需要将视觉注意力引导到太空中某个位置的任务方面具有右半球优势。”Francks是最近发表在《自然通讯》上的这项研究的主要作者。
Francks suggested that for most people, the left side of the brain controls the dominant right hand. "The nerve fibers cross from left-to-right in the lower part of the brain," Francks said. He added, "In left-handers, the right hemisphere is in control of the dominant hand. The question is: what causes the asymmetry of the brain to develop differently in left-handers?"
Francks认为，对大多数人来说，大脑的左侧控制着占主导地位的右手。Francks说：“神经纤维在大脑下部从左到右交叉。”他补充道，“在左撇子中，右半球控制着占主导地位的手。问题是：是什么导致了左撇子大脑不对称的不同发展？”
TUBB4B controls a protein that gets formed into filaments called microtubules. These microtubules give structure to the insides of cells. The changes in TUBB4B that are more common in left-handers suggest that microtubules are involved in setting up the brain's normal asymmetries, Francks said.
TUBB4B控制一种蛋白质，这种蛋白质被形成称为微管的细丝。这些微管赋予细胞内部结构。Francks说，在左撇子中更常见的TUB4B的变化表明，微管参与了大脑正常不对称的建立。
The two brain hemispheres start to develop differently in the human embryo. Scientists do not know the mechanism that controls this.
在人类胚胎中，大脑的两个半球开始有不同的发育。科学家们不知道控制这种情况的机制。
"Rare genetic variants in just a handful of people can pinpoint genes that give clues to developmental mechanisms of brain asymmetry in everyone," Francks added. TUBB4B is an example.
Francks补充道：“只有少数人的罕见基因变异可以精确定位基因，为每个人大脑不对称的发育机制提供线索。”TUBB4B就是一个例子。
The study's findings were based on genetic data from more than 350,000 middle-aged to older adults in Britain. It was from the UK Biobank. About 11 percent of the people involved were left-handed.
这项研究的发现基于英国超过35万名中老年人的基因数据。它来自英国生物银行。大约11%的参与者是左撇子。
For most people, left- or right-handedness might come down to chance. Changes in the levels of some molecules during important times of brain development could influence it, Francks suggested.
对大多数人来说，左右手可能会归结为偶然。Francks认为，在大脑发育的重要时期，一些分子水平的变化可能会对其产生影响。
Historically, many cultures disapproved of left-handedness and forced people to become right-handed.
从历史上看，许多文化都不赞成使用左手，并强迫人们使用右手。
In English, the word "right" also means "correct" or "proper." And the expression a "left-handed compliment" means that a comment might seem nice but is an insult.
在英语中，“right”一词也有“correct”或“proper”的意思。“左撇子式的赞美”一词的意思是评论看起来很好，但却是一种侮辱。
The levels of left-handedness differ around the world, with lower rates in Africa, Asia and the Middle East compared to Europe and North America, Francks said.
Francks说，世界各地的左撇子水平各不相同，与欧洲和北美相比，非洲、亚洲和中东的左撇子比例较低。
"This likely reflects suppression of left-handedness in some cultures - making left-handed kids switch to right-handedness, which also used to happen in Europe and North America," Francks added.
Francks补充道：“这可能反映了一些文化中对左撇子的压制——让左撇子孩子转而使用右手，这在欧洲和北美也曾发生过。”
The new findings might have use in the field of mental health. People with schizophrenia are around twice as likely to be left-handed or ambidextrous. People with autism are around three times as likely, Francks said.
这一新发现可能会在心理健康领域发挥作用。患有精神分裂症的人左撇子或双手灵巧的可能性大约是前者的两倍。Francks说，自闭症患者的可能性大约是正常人的三倍。
He observed that genes involved in developing the brain in early life might be involved in brain asymmetry and mental health.
他观察到，早期参与大脑发育的基因可能与大脑不对称和心理健康有关。
"Our study found suggestive evidence of this, and we have also seen it in previous studies where we looked at more common genetic variants in the population," Francks added.
Francks补充道：“我们的研究发现了这方面的提示性证据，我们在之前的研究中也看到了这一点，我们在研究人群中更常见的基因变异。”
除了名气之外，Lady Gaga、Barack Obama和Bill Gates还有什么共同点？他们都是左撇子。
But why are 10 percent of people left-handed while most are right-handed?
但是为什么10%的人是左撇子，而大多数人是右撇子呢？
Researchers are trying to find out.
研究人员正试图找出答案。
A recent study identified a genetic cause of left-handedness in some people. Researchers found rare variants of a gene involved in controlling the shape of cells. They found the variants to be 2.7 times more common in left-handed people.
最近的一项研究确定了一些人左撇子的遗传原因。研究人员发现了一种罕见的与控制细胞形状有关的基因变体。他们发现这种变体在左撇子中的常见率是前者的2.7倍。
These genetic variants account for possibly 0.1 percent of left-handedness. But the researchers said a gene, called TUBB4B, might play a part in the development of brain asymmetry.
这些基因变异可能占左撇子的0.1%。但研究人员表示，一种名为TUB4B的基因可能在大脑不对称的发展中发挥作用。
In most people, the two halves, or hemispheres, of the brain have slightly different structures and are dominant for different activities.
对大多数人来说，大脑的两半或半球结构略有不同，在不同的活动中占主导地位。
"For example, most people have left-hemisphere dominance for language, and right-hemisphere dominance for tasks that require directing visual attention to a location in space," said Clyde Francks of the Max Planck Institute for Psycholinguistics in the Netherlands. Francks was the top writer of the study published recently in Nature Communications.
荷兰马克斯·普朗克心理语言学研究所的Clyde Francks说：“例如，大多数人在语言方面具有左半球优势，在需要将视觉注意力引导到太空中某个位置的任务方面具有右半球优势。”Francks是最近发表在《自然通讯》上的这项研究的主要作者。
Francks suggested that for most people, the left side of the brain controls the dominant right hand. "The nerve fibers cross from left-to-right in the lower part of the brain," Francks said. He added, "In left-handers, the right hemisphere is in control of the dominant hand. The question is: what causes the asymmetry of the brain to develop differently in left-handers?"
Francks认为，对大多数人来说，大脑的左侧控制着占主导地位的右手。Francks说：“神经纤维在大脑下部从左到右交叉。”他补充道，“在左撇子中，右半球控制着占主导地位的手。问题是：是什么导致了左撇子大脑不对称的不同发展？”
TUBB4B controls a protein that gets formed into filaments called microtubules. These microtubules give structure to the insides of cells. The changes in TUBB4B that are more common in left-handers suggest that microtubules are involved in setting up the brain's normal asymmetries, Francks said.
TUBB4B控制一种蛋白质，这种蛋白质被形成称为微管的细丝。这些微管赋予细胞内部结构。Francks说，在左撇子中更常见的TUB4B的变化表明，微管参与了大脑正常不对称的建立。
The two brain hemispheres start to develop differently in the human embryo. Scientists do not know the mechanism that controls this.
在人类胚胎中，大脑的两个半球开始有不同的发育。科学家们不知道控制这种情况的机制。
"Rare genetic variants in just a handful of people can pinpoint genes that give clues to developmental mechanisms of brain asymmetry in everyone," Francks added. TUBB4B is an example.
Francks补充道：“只有少数人的罕见基因变异可以精确定位基因，为每个人大脑不对称的发育机制提供线索。”TUBB4B就是一个例子。
The study's findings were based on genetic data from more than 350,000 middle-aged to older adults in Britain. It was from the UK Biobank. About 11 percent of the people involved were left-handed.
这项研究的发现基于英国超过35万名中老年人的基因数据。它来自英国生物银行。大约11%的参与者是左撇子。
For most people, left- or right-handedness might come down to chance. Changes in the levels of some molecules during important times of brain development could influence it, Francks suggested.
对大多数人来说，左右手可能会归结为偶然。Francks认为，在大脑发育的重要时期，一些分子水平的变化可能会对其产生影响。
Historically, many cultures disapproved of left-handedness and forced people to become right-handed.
从历史上看，许多文化都不赞成使用左手，并强迫人们使用右手。
In English, the word "right" also means "correct" or "proper." And the expression a "left-handed compliment" means that a comment might seem nice but is an insult.
在英语中，“right”一词也有“correct”或“proper”的意思。“左撇子式的赞美”一词的意思是评论看起来很好，但却是一种侮辱。
The levels of left-handedness differ around the world, with lower rates in Africa, Asia and the Middle East compared to Europe and North America, Francks said.
Francks说，世界各地的左撇子水平各不相同，与欧洲和北美相比，非洲、亚洲和中东的左撇子比例较低。
"This likely reflects suppression of left-handedness in some cultures - making left-handed kids switch to right-handedness, which also used to happen in Europe and North America," Francks added.
Francks补充道：“这可能反映了一些文化中对左撇子的压制——让左撇子孩子转而使用右手，这在欧洲和北美也曾发生过。”
The new findings might have use in the field of mental health. People with schizophrenia are around twice as likely to be left-handed or ambidextrous. People with autism are around three times as likely, Francks said.
这一新发现可能会在心理健康领域发挥作用。患有精神分裂症的人左撇子或双手灵巧的可能性大约是前者的两倍。Francks说，自闭症患者的可能性大约是正常人的三倍。
He observed that genes involved in developing the brain in early life might be involved in brain asymmetry and mental health.
他观察到，早期参与大脑发育的基因可能与大脑不对称和心理健康有关。
"Our study found suggestive evidence of this, and we have also seen it in previous studies where we looked at more common genetic variants in the population," Francks added.
Francks补充道：“我们的研究发现了这方面的提示性证据，我们在之前的研究中也看到了这一点，我们在研究人群中更常见的基因变异。”
