0:00:00.724,0:00:02.972 This is poo, 0:00:02.972,0:00:05.455 and what I want to do today is share my passion 0:00:05.455,0:00:08.598 for poo with you, 0:00:08.598,0:00:11.411 which might be quite difficult, 0:00:11.411,0:00:14.504 but I think what you might find more fascinating 0:00:14.504,0:00:17.705 is the way these small animals deal with poo. 0:00:17.705,0:00:20.057 So this animal here has got a brain 0:00:20.057,0:00:24.017 about the size of a grain of rice, and yet it can do things 0:00:24.017,0:00:27.767 that you and I couldn't possibly entertain the idea of doing. 0:00:27.767,0:00:31.889 And basically it's all evolved to handle its food source, 0:00:31.889,0:00:34.023 which is dung. 0:00:34.023,0:00:36.602 So the question is, where do we start this story? 0:00:36.602,0:00:39.627 And it seems appropriate to start at the end, 0:00:39.627,0:00:42.412 because this is a waste product that comes out 0:00:42.412,0:00:45.985 of other animals, but it still contains nutrients 0:00:45.985,0:00:47.942 and there are sufficient nutrients in there 0:00:47.942,0:00:50.905 for dung beetles basically to make a living, 0:00:50.905,0:00:53.840 and so dung beetles eat dung, and their larvae 0:00:53.840,0:00:55.995 are also dung-feeders. 0:00:55.995,0:00:59.225 They are grown completely in a ball of dung. 0:00:59.225,0:01:03.020 Within South Africa, we've got about 800 species of dung beetles, 0:01:03.020,0:01:06.290 in Africa we've got 2,000 species of dung beetles, 0:01:06.290,0:01:10.888 and in the world we have about 6,000 species of dung beetles. 0:01:10.888,0:01:16.026 So, according to dung beetles, dung is pretty good. 0:01:16.026,0:01:18.698 Unless you're prepared to get dung under your fingernails 0:01:18.698,0:01:21.467 and root through the dung itself, you'll never see 0:01:21.467,0:01:23.758 90 percent of the dung beetle species, 0:01:23.758,0:01:26.164 because they go directly into the dung, 0:01:26.164,0:01:28.776 straight down below it, and then they shuttle back and forth 0:01:28.776,0:01:30.831 between the dung at the soil surface 0:01:30.831,0:01:33.771 and a nest they make underground. 0:01:33.771,0:01:39.016 So the question is, how do they deal with this material? 0:01:39.016,0:01:42.996 And most dung beetles actually wrap it into a package of some sort. 0:01:42.996,0:01:46.676 Ten percent of the species actually make a ball, 0:01:46.676,0:01:50.838 and this ball they roll away from the dung source, 0:01:50.838,0:01:54.274 usually bury it at a remote place away from the dung source, 0:01:54.274,0:01:57.579 and they have a very particular behavior 0:01:57.579,0:02:02.554 by which they are able to roll their balls. 0:02:02.554,0:02:06.147 So this is a very proud owner of a beautiful dung ball. 0:02:06.147,0:02:07.382 You can see it's a male 0:02:07.382,0:02:09.623 because he's got a little hair on the back of his legs there, 0:02:09.623,0:02:14.692 and he's clearly very pleased about what he's sitting on there. 0:02:14.692,0:02:16.604 And then he's about to become a victim 0:02:16.604,0:02:21.853 of a vicious smash-and-grab. (Laughter) 0:02:21.853,0:02:24.551 And this is a clear indication 0:02:24.551,0:02:27.162 that this is a valuable resource. 0:02:27.162,0:02:31.287 And so valuable resources have to be looked after 0:02:31.287,0:02:34.606 and guarded in a particular way, and we think 0:02:34.606,0:02:37.908 the reason they roll the balls away is because of this, 0:02:37.908,0:02:40.318 because of the competition that is involved 0:02:40.318,0:02:42.193 in getting hold of that dung. 0:02:42.193,0:02:45.390 So this dung pat was actually -- well, it was a dung pat 0:02:45.390,0:02:47.836 15 minutes before this photograph was taken, 0:02:47.836,0:02:50.885 and we think it's the intense competition 0:02:50.885,0:02:54.765 that makes the beetles so well-adapted 0:02:54.765,0:02:57.454 to rolling balls of dung. 0:02:57.454,0:02:59.487 So what you've got to imagine here is this animal here 0:02:59.487,0:03:03.090 moving across the African veld. 0:03:03.090,0:03:06.438 Its head is down. It's walking backwards. 0:03:06.438,0:03:11.809 It's the most bizarre way to actually transport your food in any particular direction, 0:03:11.809,0:03:14.675 and at the same time it's got to deal with the heat. 0:03:14.675,0:03:16.663 This is Africa. It's hot. 0:03:16.663,0:03:18.370 So what I want to share with you now 0:03:18.370,0:03:21.545 are some of the experiments that myself and my colleagues 0:03:21.545,0:03:26.386 have used to investigate how dung beetles 0:03:26.386,0:03:28.438 deal with these problems. 0:03:28.438,0:03:30.975 So watch this beetle, 0:03:30.975,0:03:35.119 and there's two things that I would like you to be aware of. 0:03:35.119,0:03:37.681 The first is how it deals with this obstacle 0:03:37.681,0:03:40.569 that we've put in its way. See, look, it does a little dance, 0:03:40.569,0:03:43.503 and then it carries on in exactly the same direction 0:03:43.503,0:03:47.193 that it took in the first place. 0:03:47.193,0:03:50.959 A little dance, and then heads off in a particular direction. 0:03:50.959,0:03:54.336 So clearly this animal knows where it's going 0:03:54.336,0:03:55.675 and it knows where it wants to go, 0:03:55.675,0:03:57.560 and that's a very, very important thing, 0:03:57.560,0:03:59.975 because if you think about it, you're at the dung pile, 0:03:59.975,0:04:04.498 you've got this great big pie that you want to get away from everybody else, 0:04:04.498,0:04:07.391 and the quickest way to do it is in a straight line. 0:04:07.391,0:04:11.770 So we gave them some more tasks to deal with, 0:04:11.770,0:04:15.930 and what we did here is we turned the world 0:04:15.930,0:04:19.609 under their feet. And watch its response. 0:04:25.287,0:04:28.083 So this animal has actually had the whole world 0:04:28.083,0:04:30.930 turned under its feet. It's turned by 90 degrees. 0:04:30.930,0:04:33.402 But it doesn't flinch. It knows exactly where it wants to go, 0:04:33.402,0:04:36.370 and it heads off in that particular direction. 0:04:36.370,0:04:38.562 So our next question then was, 0:04:38.562,0:04:40.522 how are they doing this? 0:04:40.522,0:04:43.971 What are they doing? And there was a cue that was available to us. 0:04:43.971,0:04:47.098 It was that every now and then they'd climb on top of the ball 0:04:47.098,0:04:49.730 and they'd take a look at the world around them. 0:04:49.730,0:04:51.450 And what do you think they could be looking at 0:04:51.450,0:04:53.126 as they climb on top of the ball? 0:04:53.126,0:04:56.681 What are the obvious cues that this animal could use 0:04:56.681,0:05:00.859 to direct its movement? And the most obvious one 0:05:00.859,0:05:05.078 is to look at the sky, and so we thought, 0:05:05.078,0:05:07.342 now what could they be looking at in the sky? 0:05:07.342,0:05:11.451 And the obvious thing to look at is the sun. 0:05:11.451,0:05:14.405 So a classic experiment here, 0:05:14.405,0:05:17.944 in that what we did was we moved the sun. 0:05:17.944,0:05:20.685 What we're going to do now is shade the sun with a board 0:05:20.685,0:05:22.655 and then move the sun with a mirror 0:05:22.655,0:05:24.521 to a completely different position. 0:05:24.521,0:05:26.433 And look at what the beetle does. 0:05:26.433,0:05:29.264 It does a little double dance, 0:05:29.264,0:05:31.543 and then it heads back in exactly the same direction 0:05:31.543,0:05:33.952 it went in the first place. 0:05:33.952,0:05:37.679 What happens now? So clearly they're looking at the sun. 0:05:37.679,0:05:40.941 The sun is a very important cue in the sky for them. 0:05:40.941,0:05:43.566 The thing is the sun is not always available to you, 0:05:43.566,0:05:47.982 because at sunset it disappears below the horizon. 0:05:47.982,0:05:50.566 What is happening in the sky here 0:05:50.566,0:05:54.225 is that there's a great big pattern of polarized light in the sky 0:05:54.225,0:05:57.976 that you and I can't see. It's the way our eyes are built. 0:05:57.976,0:06:01.679 But the sun is at the horizon over here 0:06:01.679,0:06:04.646 and we know that when the sun is at the horizon, 0:06:04.646,0:06:06.190 say it's over on this side, 0:06:06.190,0:06:10.775 there is a north-south, a huge pathway across the sky 0:06:10.775,0:06:13.248 of polarized light that we can't see 0:06:13.248,0:06:16.046 that the beetles can see. 0:06:16.046,0:06:18.905 So how do we test that? Well, that's easy. 0:06:18.905,0:06:21.847 What we do is we get a great big polarization filter, 0:06:21.847,0:06:26.271 pop the beetle underneath it, and the filter is at right angles 0:06:26.271,0:06:28.921 to the polarization pattern of the sky. 0:06:28.921,0:06:33.091 The beetle comes out from underneath the filter 0:06:33.091,0:06:35.594 and it does a right-hand turn, 0:06:35.594,0:06:37.788 because it comes back under the sky 0:06:37.788,0:06:40.607 that it was originally orientated to 0:06:40.607,0:06:42.952 and then reorientates itself back 0:06:42.952,0:06:46.874 to the direction it was originally going in. 0:06:46.874,0:06:52.691 So obviously beetles can see polarized light. 0:06:52.691,0:06:55.448 Okay, so what we've got so far is, 0:06:55.448,0:06:58.224 what are beetles doing? They're rolling balls. 0:06:58.224,0:07:01.239 How are they doing it? Well, they're rolling them in a straight line. 0:07:01.239,0:07:04.817 How are they maintaining it in a particular straight line? 0:07:04.817,0:07:07.512 Well, they're looking at celestial cues in the sky, 0:07:07.512,0:07:09.756 some of which you and I can't see. 0:07:09.756,0:07:11.440 But how do they pick up those celestial cues? 0:07:11.440,0:07:14.484 That was what was of interest to us next. 0:07:14.484,0:07:17.672 And it was this particular little behavior, the dance, 0:07:17.672,0:07:20.591 that we thought was important, because look, 0:07:20.591,0:07:22.147 it takes a pause every now and then, 0:07:22.147,0:07:26.626 and then heads off in the direction that it wants to go in. 0:07:26.626,0:07:30.863 So what are they doing when they do this dance? 0:07:30.863,0:07:35.205 How far can we push them before they will reorientate themselves? 0:07:35.205,0:07:38.701 And in this experiment here, what we did was we forced them 0:07:38.701,0:07:41.363 into a channel, and you can see he wasn't 0:07:41.363,0:07:44.101 particularly forced into this particular channel, 0:07:44.101,0:07:49.399 and we gradually displaced the beetle by 180 degrees 0:07:49.399,0:07:53.135 until this individual ends up going in exactly the opposite direction 0:07:53.135,0:07:55.700 that it wanted to go in, in the first place. 0:07:55.700,0:07:58.501 And let's see what his reaction is 0:07:58.501,0:08:01.111 as he's headed through 90 degrees here, 0:08:01.111,0:08:03.215 and now he's going to -- when he ends up down here, 0:08:03.215,0:08:06.262 he's going to be 180 degrees in the wrong direction. 0:08:06.262,0:08:08.560 And see what his response is. 0:08:08.560,0:08:11.753 He does a little dance, he turns around, 0:08:11.753,0:08:15.487 and heads back in this. He knows exactly where he's going. 0:08:15.487,0:08:17.766 He knows exactly what the problem is, 0:08:17.766,0:08:19.361 and he knows exactly how to deal with it, 0:08:19.361,0:08:22.062 and the dance is this transition behavior 0:08:22.062,0:08:24.871 that allows them to reorientate themselves. 0:08:24.871,0:08:29.663 So that's the dance, but after spending many years 0:08:29.663,0:08:33.319 sitting in the African bush watching dung beetles on nice hot days, 0:08:33.319,0:08:35.670 we noticed that there was another behavior 0:08:35.670,0:08:38.159 associated with the dance behavior. 0:08:38.159,0:08:42.097 Every now and then, when they climb on top of the ball, 0:08:42.097,0:08:45.503 they wipe their face. 0:08:45.503,0:08:48.466 And you see him do it again. 0:08:48.466,0:08:51.447 Now we thought, now what could be going on here? 0:08:51.447,0:08:54.351 Clearly the ground is very hot, and when the ground is hot, 0:08:54.351,0:08:57.086 they dance more often, and when they do this particular dance, 0:08:57.086,0:08:59.056 they wipe the bottom of their face. 0:08:59.056,0:09:01.755 And we thought that it could be a thermoregulatory behavior. 0:09:01.755,0:09:03.765 We thought that maybe what they're doing is trying to 0:09:03.765,0:09:07.206 get off the hot soil and also spitting onto their face 0:09:07.206,0:09:09.622 to cool their head down. 0:09:09.622,0:09:14.064 So what we did was design a couple of arenas. 0:09:14.064,0:09:16.163 one was hot, one was cold. 0:09:16.163,0:09:18.540 We shaded this one. We left that one hot. 0:09:18.540,0:09:22.007 And then what we did was we filmed them with a thermal camera. 0:09:22.007,0:09:26.423 So what you're looking at here is a heat image 0:09:26.423,0:09:30.344 of the system, and what you can see here emerging 0:09:30.344,0:09:33.953 from the poo is a cool dung ball. 0:09:33.953,0:09:37.232 So the truth is, if you look at the temperature over here, 0:09:37.232,0:09:42.212 dung is cool. (Laughter) 0:09:42.212,0:09:45.430 So all we're interested in here is comparing the temperature 0:09:45.430,0:09:48.070 of the beetle against the background. 0:09:48.070,0:09:52.014 So the background here is around about 50 degrees centigrade. 0:09:52.014,0:09:54.622 The beetle itself and the ball are probably around about 0:09:54.622,0:09:56.693 30 to 35 degrees centigrade, 0:09:56.693,0:09:59.359 so this is a great big ball of ice cream 0:09:59.359,0:10:02.486 that this beetle is now transporting across the hot veld. 0:10:02.486,0:10:05.189 It isn't climbing. It isn't dancing, because 0:10:05.189,0:10:08.030 its body temperature is actually relatively low. 0:10:08.030,0:10:11.103 It's about the same as yours and mine. 0:10:11.103,0:10:16.067 And what's of interest here is that little brain is quite cool. 0:10:16.067,0:10:20.374 But if we contrast now what happens in a hot environment, 0:10:20.374,0:10:22.524 look at the temperature of the soil. 0:10:22.524,0:10:25.974 It's up around 55 to 60 degrees centigrade. 0:10:25.974,0:10:29.416 Watch how often the beetle dances. 0:10:29.416,0:10:33.958 And look at its front legs. They're roaringly hot. 0:10:33.958,0:10:36.881 So the ball leaves a little thermal shadow, 0:10:36.881,0:10:38.815 and the beetle climbs on top of the ball 0:10:38.815,0:10:43.454 and wipes its face, and all the time it's trying to cool itself down, 0:10:43.454,0:10:49.124 we think, and avoid the hot sand that it's walking across. 0:10:49.124,0:10:53.056 And what we did then was put little boots on these legs, 0:10:53.056,0:10:56.018 because this was a way to test if the legs 0:10:56.018,0:10:59.776 were involved in sensing the temperature of the soil. 0:10:59.776,0:11:03.753 And if you look over here, with boots they climb onto the ball 0:11:03.753,0:11:07.944 far less often when they had no boots on. 0:11:07.944,0:11:10.271 So we described these as cool boots. 0:11:10.271,0:11:13.193 It was a dental compound that we used to make these boots. 0:11:13.193,0:11:16.080 And we also cooled down the dung ball, so we were able 0:11:16.080,0:11:19.729 to put the ball in the fridge, gave them a nice cool dung ball, 0:11:19.729,0:11:22.280 and they climbed onto that ball far less often 0:11:22.280,0:11:23.816 than when they had a hot ball. 0:11:23.816,0:11:26.790 So this is called stilting. It's a thermal behavior 0:11:26.790,0:11:28.698 that you and I do if we cross the beach, 0:11:28.698,0:11:31.416 we jump onto a towel, somebody has this towel -- 0:11:31.416,0:11:32.639 "Sorry, I've jumped onto your towel." -- 0:11:32.639,0:11:35.203 and then you scuttle across onto somebody else's towel, 0:11:35.203,0:11:37.408 and that way you don't burn your feet. 0:11:37.408,0:11:40.209 And that's exactly what the beetles are doing here. 0:11:40.209,0:11:43.424 However, there's one more story I'd like to share with you, 0:11:43.424,0:11:44.996 and that's this particular species. 0:11:44.996,0:11:47.789 It's from a genus called Pachysoma. 0:11:47.789,0:11:50.821 There are 13 species in the genus, and they have 0:11:50.821,0:11:56.959 a particular behavior that I think you will find interesting. 0:11:56.959,0:12:01.619 This is a dung beetle. Watch what he's doing. 0:12:01.619,0:12:04.309 Can you spot the difference? 0:12:04.309,0:12:07.541 They don't normally go this slowly. It's in slow motion. 0:12:07.541,0:12:09.335 but it's walking forwards, 0:12:09.335,0:12:12.896 and it's actually taking a pellet of dry dung with it. 0:12:12.896,0:12:15.350 This is a different species in the same genus 0:12:15.350,0:12:19.222 but exactly the same foraging behavior. 0:12:19.222,0:12:22.013 There's one more interesting aspect of this 0:12:22.013,0:12:26.316 dung beetle's behavior that we found quite fascinating, 0:12:26.316,0:12:30.822 and that's that it forages and provisions a nest. 0:12:30.822,0:12:33.513 So watch this individual here, and what he's trying to do 0:12:33.513,0:12:36.233 is set up a nest. 0:12:36.233,0:12:37.942 And he doesn't like this first position, 0:12:37.942,0:12:39.565 but he comes up with a second position, 0:12:39.565,0:12:43.422 and about 50 minutes later, that nest is finished, 0:12:43.422,0:12:47.149 and he heads off to forage and provision 0:12:47.149,0:12:49.503 at a pile of dry dung pellets. 0:12:49.503,0:12:52.669 And what I want you to notice is the outward path 0:12:52.669,0:12:57.278 compared to the homeward path, and compare the two. 0:12:57.278,0:12:59.938 And by and large, you'll see that the homeward path 0:12:59.938,0:13:02.769 is far more direct than the outward path. 0:13:02.769,0:13:05.584 On the outward path, he's always on the lookout 0:13:05.584,0:13:08.049 for a new blob of dung. 0:13:08.049,0:13:09.600 On the way home, he knows where home is, 0:13:09.600,0:13:12.818 and he wants to go straight to it. 0:13:12.818,0:13:16.393 The important thing here is that this is not a one-way trip, 0:13:16.393,0:13:19.783 as in most dung beetles. The trip here is repeated 0:13:19.783,0:13:24.088 back and forth between a provisioning site and a nest site. 0:13:24.088,0:13:25.030 And watch, you're going to see 0:13:25.030,0:13:29.040 another South African crime taking place right now. (Laughter) 0:13:29.040,0:13:33.654 And his neighbor steals one of his dung pellets. 0:13:33.654,0:13:36.791 So what we're looking at here 0:13:36.791,0:13:40.119 is a behavior called path integration. 0:13:40.119,0:13:42.736 And what's taking place is that the beetle 0:13:42.736,0:13:47.039 has got a home spot, it goes out on a convoluted path 0:13:47.039,0:13:50.130 looking for food, and then when it finds food, 0:13:50.130,0:13:54.438 it heads straight home. It knows exactly where its home is. 0:13:54.438,0:13:57.463 Now there's two ways it could be doing that, 0:13:57.463,0:14:00.423 and we can test that by displacing the beetle 0:14:00.423,0:14:03.120 to a new position when it's at the foraging site. 0:14:03.120,0:14:06.414 If it's using landmarks, it will find its home. 0:14:06.414,0:14:09.829 If it is using something called path integration, 0:14:09.829,0:14:13.613 it will not find its home. It will arrive at the wrong spot, 0:14:13.613,0:14:16.037 and what it's doing here if it's using path integration 0:14:16.037,0:14:19.908 is it's counting its steps or measuring the distance out in this direction. 0:14:19.908,0:14:23.605 It knows the bearing home, and it knows it should be in that direction. 0:14:23.605,0:14:26.733 If you displace it, it ends up in the wrong place. 0:14:26.733,0:14:29.310 So let's see what happens when we put this beetle 0:14:29.310,0:14:32.626 to the test with a similar experiment. 0:14:32.626,0:14:37.012 So here's our cunning experimenter. 0:14:37.012,0:14:39.413 He displaces the beetle, 0:14:39.413,0:14:44.262 and now we have to see what is going to take place. 0:14:44.262,0:14:47.356 What we've got is a burrow. That's where the forage was. 0:14:47.356,0:14:50.303 The forage has been displaced to a new position. 0:14:50.303,0:14:52.662 If he's using landmark orientation, 0:14:52.662,0:14:54.422 he should be able to find the burrow, 0:14:54.422,0:14:57.145 because he'll be able to recognize the landmarks around it. 0:14:57.145,0:15:00.188 If he's using path integration, 0:15:00.188,0:15:03.912 then it should end up in the wrong spot over here. 0:15:03.912,0:15:06.222 So let's watch what happens 0:15:06.222,0:15:09.513 when we put the beetle through the whole test. 0:15:09.513,0:15:11.509 So there he is there. 0:15:11.509,0:15:17.769 He's about to head home, and look what happens. 0:15:17.769,0:15:20.262 Shame. 0:15:20.262,0:15:22.496 It hasn't a clue. 0:15:22.496,0:15:25.416 It starts to search for its house in the right distance 0:15:25.416,0:15:31.391 away from the food, but it is clearly completely lost. 0:15:31.391,0:15:35.609 So we know now that this animal uses path integration 0:15:35.609,0:15:39.688 to find its way around, and the callous experimenter 0:15:39.688,0:15:42.809 leads it top left and leaves it. (Laughter) 0:15:42.809,0:15:46.864 So what we're looking at here are a group of animals 0:15:46.864,0:15:48.943 that use a compass, and they use the sun as a compass 0:15:48.943,0:15:50.583 to find their way around, 0:15:50.583,0:15:53.108 and they have some sort of system 0:15:53.108,0:15:55.071 for measuring that distance, 0:15:55.071,0:15:58.408 and we know that these species here actually 0:15:58.408,0:16:01.089 count the steps. That's what they use as an odometer, 0:16:01.089,0:16:06.226 a step-counting system, to find their way back home. 0:16:06.226,0:16:09.049 We don't know yet what dung beetles use. 0:16:09.049,0:16:11.328 So what have we learned from these animals 0:16:11.328,0:16:14.329 with a brain that's the size of a grain of rice? 0:16:14.329,0:16:18.440 Well, we know that they can roll balls in a straight line 0:16:18.440,0:16:20.585 using celestial cues. 0:16:20.585,0:16:23.713 We know that the dance behavior is an orientation behavior 0:16:23.713,0:16:26.127 and it's also a thermoregulation behavior, 0:16:26.127,0:16:30.325 and we also know that they use a path integration system 0:16:30.325,0:16:32.414 for finding their way home. 0:16:32.414,0:16:36.584 So for a small animal dealing with a fairly revolting substance 0:16:36.584,0:16:39.353 we can actually learn an awful lot from these things 0:16:39.353,0:16:42.985 doing behaviors that you and I couldn't possibly do. 0:16:42.985,0:16:46.985 Thank you. (Applause)