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Humans evolved speech because they walked on two feet

This article was first published in the May 2016 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.

To better understand the human brain, neuroscientist Sophie Scott uses a universal tool: the voice. 
The cognitive neuroscientist at University College London studies the brain processes linked to speech patterns and voice recognition. Scott believes the voice is a musical instrument human beings use in a rather limited way but which, if better understood, could help us make sense of who we are, and who we used to be. WIRED talks to Scott about laughter, human evolution and the neuroscience of beatboxing. 

WIRED: Why does a neuroscientist study the human voice?
Sophie Scott: Cognitive neuroscience tries to understand the brain at the behavioural level. At the level I am at, it's about how the whole brain system relates to behaviour. Much of what we do relies on functional imaging - such as magnetic resonance imaging (MRI), which photographs neural activity, looking at blood flow changes. From that perspective, understanding the voice is really important because it's the primary source of an important human behaviour such as communication.

Most people talk to each other, and have conversations in some sort of language. Language can change but people still use it to talk to each other. So it's understanding the brain system involved in that - how you understand the way people speak, how you produce your own speech, the sounds that you make, the sort of information that the brain pulls out when it hears voices: these are the major questions that remain in neuroscience.

You suggest that by studying the human voice we could learn something about how our species evolved over time. How?
There are some really key factors that have driven human evolution, which lead us to be the very flexible animals that we are. I am very interested in how voice and speech have been part of this. If you were to go about as a quadruped, you would need to use your ribcage to support your weight and that severely limits the kind of stuff you can do with it. If a chimpanzee is laughing, it goes "ah-step, ah-step, ah-step": it can't walk and laugh simultaneously. If you stress the system - if you try talking while you're doing press-ups - that's when you notice that we couldn't have used voice in this way, had we not evolved. 

Was laughter part of the same evolutionary process?
What you can say is that the use of laughter is the same wherever you go - even among animals like rats, laughter is a social phenomenon1. That being said, among human beings there are some cultural factors that influence it. In some cultures it seems impolite to laugh in serious public places, while in other cultures, it's appropriate to laugh if you're given very bad news. In the Philippines, people will mark severely bad news with laughter.

That's something that for us is very hard to understand because you're seeing a cultural elaboration taking a certain behaviour in a different direction. On the other hand, MRI studies show that the only positive emotions we can universally recognise as a sound is laughter. Not all people can necessarily recognise cheers or sounds of contentment, but we all recognise laughter.

Recently, you've been researching beatboxing. Was it just for fun, or to make a neuro-scientific point?
What beatboxing2 revealed to me is the sheer range of things we can do with our voices. And it's amazing how much we don't know. Granted, the biomechanics of speech is phenomenally complex, but if you take a step back and have a look at beatboxing you realise that we're barely scratching the surface of what we can do with our voices. We can do so much more. It raises some interesting questions about why we can do this at all.

An analogy I use is that there was a swimming competition in the Victorian era in London, and some Native Americans were taking part. The Native Americans swam using what we would call crawl. Back then it wasn't a stroke that was known in the UK: it was thought to be very inappropriate and splashy. But it was also very fast, and the Native Americans won; the Victorians were completely blown out of the water by the crawl. The crawl is an incredibly good use of the human body shape.

We didn't evolve to crawl. It just happens to be a phenomenal use of the human shape. I think that what might have happened with speech if we'd been unlucky is that we could have evolved not to speak. It may be that speech is something that is just a phenomenally good use of this system.

1. Laughter is the only positive emotion recognised across the globe. Negative ones are much more universal, Scott says. "Fear, anger, disgust vocalisations - screaming - are recognised anywhere."
2. To study beatboxing in depth, Scott worked with the artist and beatboxer Reeps One. 
"It was very bizarre to go to the UK Beatbox Championships and ask all the artists, 'Please can we scan your brain?'," she recalls. "Luckily, Reeps accepted immediately."

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