三级皮带运输机的控制:我们为什么没有变得更聪明？进化在认知力上的极限

我们在改善我们记忆力、智力和注意力的方面投入了很多精力。甚至借助药物比如利他林（注：中枢兴奋药）和咖啡因。但是也许更聪明并不是真的那么好。一篇在心理科学协会（注：Association for Psychological Science）的杂志《心理学近期趋势》（Current Directions in Psychological）上新发布的论文警告说人类所能得到的聪明程度是有极限的，而且任何在思考能力上的增长都会随之带来一些问题。

The authors looked to evolution to understand about why humans are only as smart as we are and not any smarter. "A lot of people are interested in drugs that can enhance cognition in various ways," says Thomas Hills of the University of Warwick, who cowrote the article with Ralph Hertwig of the University of Basel. "But it seems natural to ask, why aren't we smarter already?"

这两位作者关注着进化为了明白为什么人类只像我们现在这样聪明而不是更加聪明。“许许多多人们对可以通过不同途径增强认知力的药物非常感兴趣，”华威大学的托马斯·希尔斯说，也正是他和来自巴塞尔大学的拉尔夫·赫特威一起完成的这篇论文，“但是有个问题的提出就显得自然而然， 为什么我们不会变得更聪明？”

Tradeoffs are common in evolution. It might be nice to be eight feet tall, but most hearts couldn't handle getting blood up that high. So most humans top out under six feet. Just as there are evolutionary tradeoffs for physical traits, Hills says, there are tradeoffs for intelligence. A baby's brain size is thought to be limited by, among other things, the size of the mother's pelvis; bigger brains could mean more deaths in childbirth, and the pelvis can't change substantially without changing the way we stand and walk.

在进化中，此消彼长（注：Tradeoff（此消彼长）是指在生物的生命历程（ life-history ）中，由于可供分配的资源有限，特定两个特征（ life-history characters ）间相互作用，即提高一种特征的优势的时候，另一种特征的优势将降低。）是非常常见的。长成八英尺（注：2.44 米）高可能很不错，但是大多数心脏不能将血液输送到那么高。所以大多数人类都在六英尺（注：1.83 米）以下。正如在生理特质上的进化学此消彼长一样，希尔斯说，在智力上也有此消彼长。我们认为一个婴儿的大脑尺寸被周围的东西所限制，比如母亲的骨盆。更大的大脑可能意味着在分娩时更高的死亡率，同时骨盆不会发生实质上的变化除非我们改变站立和行走的方式。

Drugs like Ritalin and amphetamines help people pay better attention. But they often only help people with lower baseline abilities; people who don't have trouble paying attention in the first place can actually perform worse when they take attention-enhancing drugs. That suggests there is some kind of upper limit to how much people can or should pay attention. "This makes sense if you think about a focused task like driving," Hills says, "where you have to pay attention, but to the right things -- which may be changing all the time. If your attention is focused on a shiny billboard or changing the channel on the radio, you're going to have problems."

像利他林和安非他明（注：解除忧郁、疲劳的药）一类的药物帮助人们更好地集中注意力。但是它们通常只对在更低的基线能力上的人们有所帮助。那些在最初在集中注意方面没有问题的人们可能在服用注意力增强药物后表现得更糟糕。这儿有些建议说，在人们所能或者所应该得到的注意力集中程度是有上限的。“这是言之有理的，如果你想想一个需要全神贯注的任务比如开车。”希尔斯说，“那是你需要集中注意力的时候，但集中在正确的地方，就是说注意力一直在改变目标。如果你的注意力一直集中在一个闪亮亮的广告牌上或者在改变收音机的频道上，你将会遇到麻烦。”

It may seem like a good thing to have a better memory, but people with excessively vivid memories have a difficult life. "Memory is a double-edged sword," Hills says. In post-traumatic stress disorder, for example, a person can't stop remembering some awful episode. "If something bad happens, you want to be able to forget it, to move on."

看起来好像拥有好的记忆力是一个好事情，但是具备过分生动记忆力的人们却有着复杂的生活。“记忆力是把双刃剑，”希尔斯说。举个例子，一个得了创伤后紧张症的人无法停止对一些可怕事件的回忆。“如果一些坏的事发生了，你希望的是能够忘掉它，继续前行。”

Even increasing general intelligence can cause problems. Hills and Hertwig cite a study of Ashkenazi Jews, who have an average IQ much higher than the general European population. This is apparently because of evolutionary selection for intelligence in the last 2,000 years. But, at the same time, Ashkenazi Jews have been plagued by inherited diseases like Tay-Sachs disease that affect the nervous system. It may be that the increase in brain power has caused an increase in disease.

甚至一般智力的增长也会带来问题。希尔斯和赫特威引用了一个对阿什肯纳兹犹太人的研究，这类人拥有的平均智力远远高于一般的欧洲人种。由于过往两千多年的智力进化选择，这是很显然的。但是，与此同时，阿什肯纳兹犹太人却被像泰氏-萨氏病这样的会影响神经系统的遗传疾病所困扰。这可能是，在脑力方面的增长会引起在疾病方面的增长。

Given all of these tradeoffs that emerge when you make people better at thinking, Hills says, it's unlikely that there will ever be a supermind. "If you have a specific task that requires more memory or more speed or more accuracy or whatever, then you could potentially take an enhancer that increases your capacity for that task," he says. "But it would be wrong to think that this is going to improve your abilities all across the board."

考虑到这么多此消彼长的例子，它在你使人们在思考能力上变得更强时发生，希尔斯说，出现超级大脑是不可能的。“如果你有一个特别任务，它需要更强的记忆力或更快的速度或者更高的准确度或者什么其他的，然后你可能可以服用一个可以为那个任务增强你的能力的强化剂，”他说，“但是认为它可以在全方位提高你的能力的想法是错误的。”