This little girl seems to have come into the world with few social skills. But she does have one crucial one and within seconds of being born she uses it. —————（1）——————. But this, the first face she's ever seen is also physically altering her brain. This first moment of Isla's social life is stimulating her brain at the tiniest level. Our brain contains complex networks of brain cells called neurons. Like all of us, Isla has been born with a staggering hundred billion of them. These neurons are connected to each other at tiny junctions called synapses. As Isla sees her mother's face for the first time, an electrical signal is created. This signal travels through these synapses along a pathway which is unique to her mother's face. As she sees another face, her father's, a different pathway is stimulated in her brain. From now on, Isla's brain will adapt and develop, creating many more pathways as she meets new people. But even at this tender age, a baby's ability to distinguish between faces is almost unbelievable.

Like all babies, little Grace here can look at the faces of primates, like these lemurs, and actually tell one from another. But what's interesting is that her older sister can't. To her, all these lemurs look the same. So how are you doing? Well, let's make it easier for you. Can you tell them apart now? No? Well you're not alone. ——————（2）——————. But, just like little Grace, there was a time in our lives when all of us could. And scientists at Sheffield University have proved it. They showed primate faces to two sets of babies, one group under six months, the other over nine months. ——————（3）——————. But when the researchers tried again with a different face, the results were astonishing. The older babies refused to look at the new face. They were bored. They thought they'd seen it before. Clearly they couldn't see the difference in the two faces. But when the younger babies were shown the new face, it was a different story they were fascinated. That's because they could see that this was a different lemur. But in order to get on in the world of humans, all babies have to lose this extraordinary skill. So what happens to make a baby's brain more like their parents? The answer to this tells us a lot about the way our brain develops its ability to communicate with other people. A baby's brain is a little bit like this tray of cress, with all the seeds representing individual connections or synapses, all doing different jobs. ——————（4）——————. This gives them skills they'll simply never need, like recognizing the difference in primate faces. Our brain now has too many synapses. It needs to specialize. Which connections live and die depends on who we look at. Human babies grow up looking almost entirely at human faces. So the connections that process these continue to survive and grow. What babies don't use they lose, including the connections that recognize primate faces. This means by ten months their skills at recognizing the difference in human faces are better than ever. As babies, ———————（5）————————, which is just as well, because the world around us is about to get far more complicated.