She wove language from the plainest of threads. Before she could talk, she could spin lengths of undifferentiated sound, just by voicing an outbreath and letting the noise push out on a flow of exhaled air. By eight weeks she could shape her mouth to make a contented ur-ur, expressing satisfaction at the way the world looked and the fact that she was at the centre of it. Her growing awareness of reality meant multiplying objects of desire, new ways for her material ambitions to be thwarted. There was a gutsy, frustrated errghh, which seemed to say I want something and I can’t quite get it from here. At other times her speech, like her crying, was simply an affirmation of her own existence. She learned to widen her mouth and push out a throaty pterodactyl squawk, alarmingly loud, not so much Feed me! as Look at me! As with the dancing animals she was learning to control at will, she was testing her own powers, exploring the limits of her ability to make things happen. The message was simple: I’m here. I can do this. Don’t ignore me.

Until now, these had all been variations on the same basic theme. Lacking any degree of tonal range, she had to rely on rhythm and phrasing to colour the limited sound that she could produce. The breakthrough came when she realised that she could do something with this pleasurable flow of excitation over her vocal cords. Changing the shape of the aperture it was escaping through, such as by making use of her growing tongue control, changed the noise that came out into something remarkably like adult language. When she moved her jaw, often breaking off from chomping on her knuckles with her budding teeth, she was biting off chunks of speech, leaving a trail of chewy, pensive vowels and syllables. She was finding different techniques for manipulating the sound source, eloquent new degrees of freedom. In fact, she had exactly what our primate cousins lack: an articulatory apparatus sophisticated enough to create the subtleties and nuances of speech. For all their propensities for learning sign language, chimps and bonobos can’t even get started on human speech. They’re not built for it; they simply cannot shape their tongues, lips and mouths into the right contortions. It turns out that they lack part of a particular gene, known as FOXP2, which is involved in the fine tuning of those subtle articulatory movements we need for producing speech. In humans, mistakes in this gene lead to great difficulties in producing intelligible spoken language. Without the right version of FOXP2, the simplest string of words would be a tongue-twister.
 

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