To discover how lions produce their roar,
our team travelled to Gondwana Game Reserve near Cape Town.
Amongst the many wild animals found here are several lions.
And when they roar... ROARS
..they can be heard as far as eight kilometres away.
Biologist Professor Craig Packer is about to conduct an experiment
that will help to unravel exactly how
the lion produces such a powerful sound.
His first task is to locate the lions.
What's your strategy for tracking them?
Craig, we've got three adult lions on the reserve.
One adult male, two adult females, and they're all collared.
Assisting Craig is Gondwana's Jono Berry.
INTERFERENCE AND BEEPS
OK, we've got a beautiful signal on the male there.
OK. So that's the direction.
Pull in here.
Excellent. OK. So there he is, on the road.
After locating the lone male,
Jono and Craig place a loudspeaker on the ground...
..and retreat to the safety of their vehicle.
So, he's the only male in the reserve here?
He's the only adult male that we have on the property at the moment.
And he's never been challenged. No. He's always been the big boss.
So he's a little overconfident.
Using the speaker, Craig is going to play a recording
of another male lion's roar.
So this should be quite a shock when we play him that roar.
He's going to get the fright of his life.
He'll also capture the lion's response.
I'm pretty sure he's going to get up to investigate and hopefully
we're going to get a loud roar coming out of him
as he walks along announcing,
"This land is my land. You get out of here."
OK, well, let's give it a go.
OK. Let's go.
ROAR
On hearing the recording, the lion immediately springs into action.
ROARS
He responds... ROARS
..with some roars of his own...
ROARS
..and sets off in search of the intruder.
With the help of some specialist software,
Craig analyses the roars he's just recorded.
His data shows something very interesting.
The roars change frequency.
What we have here is a roar element.
It starts out very low frequency, comes up higher and comes back down
to the lowest frequency at the very end.
Up and down, up and down.
So this is like taking one of these little penny whistles here and...
PLAYS DESCENDING NOTE
..lengthening the sound chamber, lowering the pitch.
This drop in frequency or pitch is a clue
to how lions produce their roar.
So, physiologically one of the striking things
is that they have a special sound-making apparatus.
SERIES OF ROARS
Recently it's been discovered that the larynx is attached
to the ribcage at a much lower level than other mammals.
Like all mammals, a lion's larynx is controlled by several strips
of muscle that connect it to the ribcage.
But while in other animals these strap muscles are relatively short,
in lions they are much longer.
These strap muscles attach to the human larynx
up at our top rib.
But for the lions and tigers, etc, it's down about the third or fourth rib.
This increased length is vital.
It's thought that when a lion roars...
ROARS
..its elongated strap muscles enable the larynx to be pulled
far down into the windpipe.
And this extra distance between the larynx and mouth...
..is what allows the lion's deep-throated roar
to carry over such vast distances.
There are several major lineages of cats, and the one that includes
the domestic cat, of course, can meow but it can't roar.
There are cats from Latin America that climb trees
and again, they don't roar.
It's only in the genus Panthera, that includes the lion, the tiger,
the jaguar and the leopard, that is capable of roaring.
An unmistakable trait made possible by the evolutionary
adaptation of the larynx.