The Hello and welcome to the naked scientists with me Ginny Smith and with Hannah Crichlow.

This week the science behind how you get your feet to dance to the

beat. How DJ's get us all in the groove. The new 10 million pound science prize which

the government is hoping you could win and will

spectators at the World Cup be at risk of Dengue fever. Plus we'll be

discussing some ethical questions about medicine. How do we decide which drugs

should be available on the NHS and will designer babies become more commonplace in

the future? The Naked Scientists Podcast is powered by UKfast.co.uk. UK. First up, have you ever been on the dance floor getting your grieve on, enjoying a particular tune,

and then the DJ flips the song over and it completely messes up your dancing moves. I have and in fact that

definitely affected me last night at a party. Well what's the science behind this DJ

skill? Mark Elliot is a research fellow at Birmingham University and he thinks he's

found the answer. Hello Mark. Hi there. So what makes a good DJ?

So a good DJ basically needs to mix two songs lines from two separate songs

and then closely match them up together so they sound like a common beat.

And if they get it wrong, it can sound pretty horrible and sound like this. So that's enough to put you off your dance in and is literally only like a few

tens of milliseconds out. So what we wanted to find out is how accurately those beat lines need to be matched for people to start moving in time to them as if they were a single common beat.

And how did you study that then? Did you go out to lots of clubs and start measuring people's dance moves?

It wasn't quite that exciting.

So we did a lab-based experiment where people basically had to just tap along to two metronomes played at the same time.

So what we did with those metronomes is vary the separation between them

and also the consistency and the predictability of the beats of the separate metronome. So we've probably got some examples I think. in the

predictability of the beats of the separate metronome. So we've probably got some examples I think. So this is a consistent metronome

...