From the most dramatic moment in life – the day of your birth – to first steps, first words, first food, right up to nursery school, most of us can't remember anything of our first few years. How come?

从你一生当中最激动人心的时刻——你的出生日开始，到第一次走路，第一次说话，第一次吃东西，一直到上幼儿园，我们大多数人不记得生命中头几年的事情了。这是怎么回事呢？

This gaping¹ hole in the record of our lives has been baffling psychologists, neuroscientists and linguists² for decades. It was a minor³ obsession⁴ of the father of psychotherapy, Sigmund Freud, who coined the phrase 'infant amnesia⁵' over 100 years ago.

我们生命记录中的这一空白已经困扰心理学家、神经系统科学家和语言学家数十年了。心理疗法之父西格蒙德·弗洛伊德对此也颇有研究，他于100多年前创造了"婴儿健忘症"一词。

Part of the puzzle comes from the fact that babies are, in other ways, sponges for new information, forming 700 new neural⁶ connections every second and wielding⁷ language-learning skills to make the most accomplished⁸ polyglot⁹ green with envy. The latest research suggests they begin training their minds before they've even left the womb.

从另一方面来说，该困惑的部分原因在于婴儿能够不断吸收新的信息，每秒钟可形成700个新的神经连接，并通过语言习得技能引得精通数国语言的人投之以羡慕之情。最新的研究表明，他们甚至在母亲分娩之后便开始训练自己的大脑了。

But even as adults, information is lost over time if there's no attempt to retain it. So one explanation is that infant amnesia is simply a result of the natural process of forgetting the things we experience throughout our lives.

但即便是成年人，若不刻意记忆，信息也会随着时光流逝而消失。因此，就有解释称，婴儿健忘症仅仅是我们一生当中忘记我们所经历过的事情这一自然过程的一个结果。

Our culture may also determine the way we talk about our memories, with some psychologists arguing that they only come once we have mastered the power of speech.

我们的文化也决定着我们谈论记忆力的方式。一些心理学家表示，只有当我们掌握了说话的能力，我们才会有记忆力。

This leads us to the theory that we can't remember our first years simply because our brains hadn't developed the necessary equipment. The explanation emerges from the most famous man in the history of neuroscience, known simply as patient HM.

这样我们便可得出结论，我们记不住头几年的事情仅仅是因为我们的大脑还未发育出必需的物质。这一解释的出现得益于神经科学史上最有名人物，他被戏称为病人HM。

Perhaps, when we're very young, the hippocampus simply isn't developed enough to build a rich memory of an event. Baby rats, monkeys and humans all continue to add new neurons to the hippocampus for the first few years of life and we all are all unable to form lasting¹⁰ memories as infants – and it seems that the moment we stop creating new neurons, we're suddenly able to form long-term memories.

或许，当我们还很小的时候，海马体尚未发育成熟，因此我们无法对一件事情形成丰富的记忆。幼鼠，幼猴和婴儿在生命开始的头几年都会持续向海马体增加新的神经元，而与此同时，我们也都像婴儿一样无法形成长久的记忆--似乎当我们停止增加新的神经元时，我们便突然之间能够形成长久的记忆了。

Perhaps the biggest mystery is not why we can't remember our childhood – but whether we can believe any of our memories at all.

或许最大的谜团并非我们为何无法回忆起我们的童年，而是我们是否能够完全相信自己的记忆。