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This is poo,

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and what I want to do today is share my passion

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for poo with you,

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which might be quite difficult,

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but I think what you might find more fascinating

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is the way these small animals deal with poo.

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So this animal here has got a brain

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about the size of a grain of rice, and yet it can do things

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that you and I couldn't possibly entertain the idea of doing.

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And basically it's all evolved to handle its food source,

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which is dung.

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So the question is, where do we start this story?

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And it seems appropriate to start at the end,

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because this is a waste product that comes out

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of other animals, but it still contains nutrients

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and there are sufficient nutrients in there

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for dung beetles basically to make a living,

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and so dung beetles eat dung, and their larvae

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are also dung-feeders.

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They are grown completely in a ball of dung.

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Within South Africa, we've got about 800 species of dung beetles,

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in Africa we've got 2,000 species of dung beetles,

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and in the world we have about 6,000 species of dung beetles.

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So, according to dung beetles, dung is pretty good.

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Unless you're prepared to get dung under your fingernails

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and root through the dung itself, you'll never see

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90 percent of the dung beetle species,

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because they go directly into the dung,

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straight down below it, and then they shuttle back and forth

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between the dung at the soil surface

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and a nest they make underground.

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So the question is, how do they deal with this material?

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And most dung beetles actually wrap it into a package of some sort.

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Ten percent of the species actually make a ball,

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and this ball they roll away from the dung source,

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usually bury it at a remote place away from the dung source,

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and they have a very particular behavior

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by which they are able to roll their balls.

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So this is a very proud owner of a beautiful dung ball.

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You can see it's a male

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because he's got a little hair on the back of his legs there,

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and he's clearly very pleased about what he's sitting on there.

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And then he's about to become a victim

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of a vicious smash-and-grab. (Laughter)

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And this is a clear indication

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that this is a valuable resource.

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And so valuable resources have to be looked after

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and guarded in a particular way, and we think

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the reason they roll the balls away is because of this,

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because of the competition that is involved

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in getting hold of that dung.

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So this dung pat was actually -- well, it was a dung pat

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15 minutes before this photograph was taken,

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and we think it's the intense competition

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that makes the beetles so well-adapted

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to rolling balls of dung.

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So what you've got to imagine here is this animal here

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moving across the African veld.

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Its head is down. It's walking backwards.

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It's the most bizarre way to actually transport your food in any particular direction,

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and at the same time it's got to deal with the heat.

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This is Africa. It's hot.

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So what I want to share with you now

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are some of the experiments that myself and my colleagues

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have used to investigate how dung beetles

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deal with these problems.

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So watch this beetle,

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and there's two things that I would like you to be aware of.

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The first is how it deals with this obstacle

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that we've put in its way. See, look, it does a little dance,

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and then it carries on in exactly the same direction

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that it took in the first place.

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A little dance, and then heads off in a particular direction.

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So clearly this animal knows where it's going

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and it knows where it wants to go,

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and that's a very, very important thing,

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because if you think about it, you're at the dung pile,

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you've got this great big pie that you want to get away from everybody else,

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and the quickest way to do it is in a straight line.

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So we gave them some more tasks to deal with,

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and what we did here is we turned the world

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under their feet. And watch its response.

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So this animal has actually had the whole world

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turned under its feet. It's turned by 90 degrees.

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But it doesn't flinch. It knows exactly where it wants to go,

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and it heads off in that particular direction.

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So our next question then was,

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how are they doing this?

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What are they doing? And there was a cue that was available to us.

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It was that every now and then they'd climb on top of the ball

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and they'd take a look at the world around them.

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And what do you think they could be looking at

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as they climb on top of the ball?

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What are the obvious cues that this animal could use

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to direct its movement? And the most obvious one

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is to look at the sky, and so we thought,

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now what could they be looking at in the sky?

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And the obvious thing to look at is the sun.

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So a classic experiment here,

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in that what we did was we moved the sun.

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What we're going to do now is shade the sun with a board

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and then move the sun with a mirror

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to a completely different position.

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And look at what the beetle does.

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It does a little double dance,

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and then it heads back in exactly the same direction

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it went in the first place.

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What happens now? So clearly they're looking at the sun.

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The sun is a very important cue in the sky for them.

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The thing is the sun is not always available to you,

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because at sunset it disappears below the horizon.

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What is happening in the sky here

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is that there's a great big pattern of polarized light in the sky

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that you and I can't see. It's the way our eyes are built.

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But the sun is at the horizon over here

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and we know that when the sun is at the horizon,

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say it's over on this side,

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there is a north-south, a huge pathway across the sky

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of polarized light that we can't see

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that the beetles can see.

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So how do we test that? Well, that's easy.

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What we do is we get a great big polarization filter,

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pop the beetle underneath it, and the filter is at right angles

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to the polarization pattern of the sky.

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The beetle comes out from underneath the filter

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and it does a right-hand turn,

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because it comes back under the sky

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that it was originally orientated to

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and then reorientates itself back

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to the direction it was originally going in.

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So obviously beetles can see polarized light.

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Okay, so what we've got so far is,

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what are beetles doing? They're rolling balls.

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How are they doing it? Well, they're rolling them in a straight line.

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How are they maintaining it in a particular straight line?

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Well, they're looking at celestial cues in the sky,

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some of which you and I can't see.

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But how do they pick up those celestial cues?

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That was what was of interest to us next.

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And it was this particular little behavior, the dance,

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that we thought was important, because look,

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it takes a pause every now and then,

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and then heads off in the direction that it wants to go in.

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So what are they doing when they do this dance?

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How far can we push them before they will reorientate themselves?

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And in this experiment here, what we did was we forced them

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into a channel, and you can see he wasn't

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particularly forced into this particular channel,

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and we gradually displaced the beetle by 180 degrees

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until this individual ends up going in exactly the opposite direction

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that it wanted to go in, in the first place.

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And let's see what his reaction is

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as he's headed through 90 degrees here,

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and now he's going to -- when he ends up down here,

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he's going to be 180 degrees in the wrong direction.

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And see what his response is.

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He does a little dance, he turns around,

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and heads back in this. He knows exactly where he's going.

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He knows exactly what the problem is,

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and he knows exactly how to deal with it,

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and the dance is this transition behavior

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that allows them to reorientate themselves.

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So that's the dance, but after spending many years

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sitting in the African bush watching dung beetles on nice hot days,

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we noticed that there was another behavior

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associated with the dance behavior.

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Every now and then, when they climb on top of the ball,

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they wipe their face.

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And you see him do it again.

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Now we thought, now what could be going on here?

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Clearly the ground is very hot, and when the ground is hot,

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they dance more often, and when they do this particular dance,

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they wipe the bottom of their face.

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And we thought that it could be a thermoregulatory behavior.

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We thought that maybe what they're doing is trying to

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get off the hot soil and also spitting onto their face

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to cool their head down.

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So what we did was design a couple of arenas.

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one was hot, one was cold.

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We shaded this one. We left that one hot.

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And then what we did was we filmed them with a thermal camera.

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So what you're looking at here is a heat image

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of the system, and what you can see here emerging

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from the poo is a cool dung ball.

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So the truth is, if you look at the temperature over here,

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dung is cool. (Laughter)

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So all we're interested in here is comparing the temperature

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of the beetle against the background.

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So the background here is around about 50 degrees centigrade.

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The beetle itself and the ball are probably around about

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30 to 35 degrees centigrade,

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so this is a great big ball of ice cream

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that this beetle is now transporting across the hot veld.

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It isn't climbing. It isn't dancing, because

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its body temperature is actually relatively low.

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It's about the same as yours and mine.

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And what's of interest here is that little brain is quite cool.

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But if we contrast now what happens in a hot environment,

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look at the temperature of the soil.

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It's up around 55 to 60 degrees centigrade.

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Watch how often the beetle dances.

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And look at its front legs. They're roaringly hot.

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So the ball leaves a little thermal shadow,

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and the beetle climbs on top of the ball

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and wipes its face, and all the time it's trying to cool itself down,

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we think, and avoid the hot sand that it's walking across.

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And what we did then was put little boots on these legs,

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because this was a way to test if the legs

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were involved in sensing the temperature of the soil.

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And if you look over here, with boots they climb onto the ball

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far less often when they had no boots on.

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So we described these as cool boots.

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It was a dental compound that we used to make these boots.

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And we also cooled down the dung ball, so we were able

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to put the ball in the fridge, gave them a nice cool dung ball,

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and they climbed onto that ball far less often

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than when they had a hot ball.

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So this is called stilting. It's a thermal behavior

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that you and I do if we cross the beach,

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we jump onto a towel, somebody has this towel --

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"Sorry, I've jumped onto your towel." --

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and then you scuttle across onto somebody else's towel,

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and that way you don't burn your feet.

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And that's exactly what the beetles are doing here.

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However, there's one more story I'd like to share with you,

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and that's this particular species.

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It's from a genus called Pachysoma.

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There are 13 species in the genus, and they have

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a particular behavior that I think you will find interesting.

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This is a dung beetle. Watch what he's doing.

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Can you spot the difference?

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They don't normally go this slowly. It's in slow motion.

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but it's walking forwards,

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and it's actually taking a pellet of dry dung with it.

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This is a different species in the same genus

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but exactly the same foraging behavior.

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There's one more interesting aspect of this

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dung beetle's behavior that we found quite fascinating,

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and that's that it forages and provisions a nest.

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So watch this individual here, and what he's trying to do

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is set up a nest.

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And he doesn't like this first position,

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but he comes up with a second position,

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and about 50 minutes later, that nest is finished,

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and he heads off to forage and provision

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at a pile of dry dung pellets.

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And what I want you to notice is the outward path

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compared to the homeward path, and compare the two.

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And by and large, you'll see that the homeward path

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is far more direct than the outward path.

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On the outward path, he's always on the lookout

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for a new blob of dung.

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On the way home, he knows where home is,

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and he wants to go straight to it.

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The important thing here is that this is not a one-way trip,

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as in most dung beetles. The trip here is repeated

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back and forth between a provisioning site and a nest site.

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And watch, you're going to see

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another South African crime taking place right now. (Laughter)

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And his neighbor steals one of his dung pellets.

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So what we're looking at here

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is a behavior called path integration.

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And what's taking place is that the beetle

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has got a home spot, it goes out on a convoluted path

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looking for food, and then when it finds food,

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it heads straight home. It knows exactly where its home is.

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Now there's two ways it could be doing that,

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and we can test that by displacing the beetle

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to a new position when it's at the foraging site.

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If it's using landmarks, it will find its home.

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If it is using something called path integration,

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it will not find its home. It will arrive at the wrong spot,

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and what it's doing here if it's using path integration

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is it's counting its steps or measuring the distance out in this direction.

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It knows the bearing home, and it knows it should be in that direction.

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If you displace it, it ends up in the wrong place.

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So let's see what happens when we put this beetle

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to the test with a similar experiment.

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So here's our cunning experimenter.

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He displaces the beetle,

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and now we have to see what is going to take place.

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What we've got is a burrow. That's where the forage was.

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The forage has been displaced to a new position.

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If he's using landmark orientation,

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he should be able to find the burrow,

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because he'll be able to recognize the landmarks around it.

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If he's using path integration,

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then it should end up in the wrong spot over here.

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So let's watch what happens

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when we put the beetle through the whole test.

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So there he is there.

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He's about to head home, and look what happens.

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Shame.

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It hasn't a clue.

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It starts to search for its house in the right distance

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away from the food, but it is clearly completely lost.

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So we know now that this animal uses path integration

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to find its way around, and the callous experimenter

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leads it top left and leaves it. (Laughter)

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So what we're looking at here are a group of animals

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that use a compass, and they use the sun as a compass

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to find their way around,

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and they have some sort of system

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for measuring that distance,

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and we know that these species here actually

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count the steps. That's what they use as an odometer,

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a step-counting system, to find their way back home.

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We don't know yet what dung beetles use.

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So what have we learned from these animals

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with a brain that's the size of a grain of rice?

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Well, we know that they can roll balls in a straight line

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using celestial cues.

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We know that the dance behavior is an orientation behavior

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and it's also a thermoregulation behavior,

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and we also know that they use a path integration system

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for finding their way home.

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So for a small animal dealing with a fairly revolting substance

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we can actually learn an awful lot from these things

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doing behaviors that you and I couldn't possibly do.

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Thank you. (Applause)