"腦袋大"的人一定是天才嗎?

At Einstein’s autopsy in 1955, his brain was something of a disappointment: it turned out to be a tad smaller than the average Joe’s. Indeed, later studies have suggested a minimal link between brain size and intelligence. It seems brain quality rather than quantity is key。

在1955 年對愛因斯坦屍體的解剖中，他的大腦多少讓人有些失望——它比一個成年男子大腦的平均體積還稍微小一點。其實後來的研究也指出，大腦的體積與智力的關係極微，似乎“質”比“量”更爲關鍵。

One important factor seems to be how well our neurons can talk to each other. Martijn van den Heuvel, a neuroscientist at Utrecht University Medical Center in the Netherlands, found that smarter brains seem to have more efficient networks between neurons – in other words, it takes fewer steps to relay a message between different regions of the brain. That could explain about a third of the variation in a population’s IQ, he says。

一個重要的因素就是我們大腦中的神經元相互的交流度有多好。荷蘭烏特勒支大學醫學中心的神經科學家馬丁·範登·赫維爾發現，較聰明的大腦似乎擁有更加有效的神經元網絡，換句話說就是信息在大腦不同區域間傳遞所花費的步驟更少。他說，人類1/3 的智力差異都是由於這個原因。

Another key factor is the insulating fatty sheath encasing neuron fibers, which affects the speed of electrical signals. Paul Thompson at the University of California, Los Angeles, has found a correlation between IQ and the quality of the sheaths。

另一個關鍵要素是將神經纖維與外界隔離的脂肪鞘，它可以影響電信號的傳輸速度。加利福尼亞大學洛杉磯分校的保羅·湯普森發現，智力與脂肪鞘質量之間是有關聯的。

We still don’t know exactly how much genes contribute to intelligence, with various studies coming up with estimates rangingfrom 40 to 80 per cent. This wide range of estimates might have arisen because genes contribute more to IQ as we get older, according to a study published last year. By comparing the intelligence of 11,000 pairs of twins, Robert Plomin of King’s College London found that at age 9, genes explain 40 per cent of the variation, but by 17 they account for roughly two-thirds。

對於基因對智力起的作用佔多少，各種研究估計出的比例從40% 到 80% 不等，我們仍然無法確定具體數字。根據去年公佈的一項研究，這個寬泛的估計值可能會升高，因爲隨着年齡的增長，基因對智力的作用會越來越大。通過對1.1 萬對雙胞胎智力的比較，倫敦國王學院的羅伯特·普洛明發現，9歲的時候，40%的智力差異是由基因影響的，而到了17 歲，比例升到了大概2/3。

How could that be? Perhaps the genes affect how our brain rewires itself as we mature. Alternatively, they may dictate whether someone is likely to seek out stimulating experiences to help their brain grow and develop. “If we are predisposed to have a talent, we may actively seek out an environment to suit it,” says Thompson。

這種結果是如何產生的呢？也許是因爲隨着我們長大，基因會影響我們的大腦如何進行神經重塑，要麼就是基因會支配一個人是否願意去尋找有刺激性的體驗來幫助他們的大腦生長髮育。湯普森說，“如果我們預先決定要創造出一個天才，那我們可能就要積極地去尋找一個環境來配合他的成長”