Why young brains are so much better than adults' at learning.
Dad matters: Children learn such a lot in a very short time
When you think about it, 15 months is not long to learn new skills or new abilities. It is not much time to figure out what they're all about, let alone work out how to do them yourself. Learning a new language is a classic example. Many western people - including myself - have not picked up more than a smattering of Arabic words during their time in the UAE. In contrast, Astrid's learnt a lot in 15 months. She's changed from a burbling, gurgling newborn to a walking, almost-talking human being. This ability to learn so much in such a short amount of time is remarkable and it owes a lot to the way the brain is structured.
The brain is made up of long, thin cells called neurons. Information passes down these wire-like structures in the form of pulses of electricity. Between each neuron is a gap called a synapse. Each neuron monitors the electrical signals being sent to it and if the number of signals exceeds a certain number it will secrete chemicals called neurotransmitters that bridge this gap and pass the signals on to the next neuron.
The adult brain has about 10 billion neurons, each with about 1,000 connections. The infant brain has almost the same number of neurons, but the difference is that the connections between them have not set yet. "Set" is not quite the right word, for it's more that while the connections are possible, they are not well worn. In the womb, synapses are created at a rate of about two million per second and for a time we have more connections than we will have at any other point in our lives. About three months before birth a pruning process begins, a so-called "neural Darwinism" in which only the strongest synapses survive.
The pruning process continues throughout our lives, as does the forming of new connections. Thanks to this process the brain becomes more efficient, but it also becomes less flexible. So while a more mature brain can focus better, this ability comes at the expense of a more wide-ranging capacity to absorb what is going on around it. If you've ever been for a walk with a young child, you'll have seen this difference in action. Walking 50 metres with Astrid takes at least five minutes. She stops to look at the ground. She toddles off in different directions. She waves and plays peep-o with the man in the air-conditioning shop. She wants to run up and down the stairs at the entrance to the building next door.
While this capacity to be easily distracted can be infuriating to an adult with somewhere to go, this open-mindedness also helps to explain why babies can learn so many new things so quickly. They don't seem to worry about what they are going to do with the information they take in, how they are going to use it or why it is worth remembering, they just take it in. Young children are often told to "pay attention" when their gaze starts to wander or they start doing something else. In fact, they are paying too much attention, just to the world around them rather than what they are meant to be doing.
The poet John Ashbery described the work of his friend and fellow poet Frank O'Hara as "the inspired ramblings of a mind open to the point of distraction". The way the brain develops - keeping connections that are well trammelled and pruning ones that are not - leads to a necessarily more focused and more restricted view of the world, but it is worth remembering that sometimes distraction may not always be such a bad thing.