 Naked mole rats cwm from East Africa, so they live completely underground. They're highly adapted to living underground. Most of the burrow is composed of foraging tunnels, which can, if you add them up, can extend for three or four kilometres. So massive, massive sort of labyrinths. But because those tunnels are dug, searching for roots and choovers, their food resources, they tend to be at the level of the roots. So within, say, half a metre or a metre of the surface. The more central core areas of the burrow where you find communal nesting chambers and communal toilet chambers, they can be deeper. Once in Kenya, we dug down to a nest chamber. It was about five feet underground, which is quite a lot of digging. Clearly, that's difficult for predators to get out, even the snakes that can get into burrows. And I think also it's very thermostable down at that level as well, which is good for these sort of cold-blooded mammals. The original founder stock came from Kenya. We're collected by someone who did a PhD in the wild on their ecology and behaviour, and they brought some animals back to London. Their lifestyle was really the first thing that intrigued biologists going back to the late 70s, early 80s, when it was realised that the naked mole actually behaved like a social insect. Then we have animals living together in very large groups, on average 80 to 100 in the wild, sometimes up to 300, though. Yet within these enormous colonies, there's just a single breeding female, the queen. She mates with one or two, maybe three reproductive males that she selects. And then the rest of the colony of both sexes are reproductively suppressed, and they help basically. And some of the bigger ones then may become non-workers and they adopt a defensive role. So in the non-breeders, if you take a male and a female out of the suppressing influence of the colony and pair them together away from the suppressing influences of the queen, they will quite rapidly become reproductively active. Herb has broad implications in understanding captive breeding and reproductive suppression in other species, and even maybe in humans, the mechanisms are probably likely to be very similar. So the queen generally has an elongated body. After having the first few litters, the vertebrae get longer to help accommodate these large litters. She's also the one that normally tramples over the top of everyone else when they meet in the tunnels on face-to-face encounters. She's probably in the first 20 or 30 days of pregnancy, I would say, maybe halfway through the 72 days. So their pregnancy is actually quite long for her rodent as well. Towards the end, when the queen is very, very large and pregnant, so they can have a 27 offspring in one litter, she would have great difficulty in getting down, especially the smaller tunnels in the wild, and would be dependent on the workforce bringing food back. You can see that although they're called naked mole rats, they're not in fact completely naked because they have sensory whiskers scattered along the body, which gives them an important tactile sense given that they're living in total darkness. If we can get this one to turn around and you look ahead on there, you can see the teeth that protrude outside the mouth, those front incisors, which is what they use to dig the burrows. The mouth seals behind them so they don't swallow soil as they're digging away. The external ear is also absent. The gut contains quite a potent mixture of microorganisms which help them to ferment the high cellulose content of the food. It also gives rise to one of the more unpleasant aspects of mole rat behaviour, which is coprophagy, so when the young are being weaned, they eat the feces of the adults in order to infect their digestive tract with these all-important microorganisms. The other animals we can see here will be over 20 years old and going strong. The last time I asked a colleague in the States, she had some about 32 years, so we probably don't even know the upper limit just yet. Another thing that was noted was that they appeared to not really get any of the usual age-related problems, including cancer. Recently there's been two separate naked mole rat genome projects and so far the genome project has revealed that some of the genes that we would expect, cancer genes related to low oxygen, genes that are implicated in ageing have been shown to be doing different things in naked mole rats that will have wide-ranging implications for human and animal health and understanding biology in general.