WEBVTT - Do Lemmings Really Jump Off Cliffs? 0:00:01.890 --> 0:00:07.850 Welcome to BrainStuff, a production of iHeartRadio. Hey BrainStuff, Lauren 0:00:07.870 --> 0:00:12.710 Vogelbaum here. You might have heard the term lemming in 0:00:12.810 --> 0:00:16.070 context of a metaphor for someone so foolish that they 0:00:16.110 --> 0:00:19.230 would follow a group into a bad situation rather than 0:00:19.410 --> 0:00:23.850 apply critical thinking and act accordingly. As in, what are you, 0:00:23.890 --> 0:00:26.290 a lemming? If everyone else jumped off a cliff, would 0:00:26.329 --> 0:00:30.000 you do that too? there's an idea that lemmings are 0:00:30.090 --> 0:00:35.640 creatures prone to mindlessly jumping off cliffs en masse. However, 0:00:35.880 --> 0:00:39.660 the root of this metaphor is not impressionable people. Lemmings 0:00:39.720 --> 0:00:42.600 are actually several species of small rodents native to the 0:00:42.729 --> 0:00:46.650 Arctic regions of the globe. Most closely related to voles 0:00:46.690 --> 0:00:50.710 and muskrats, lemmings are stocky little creatures with short tails, ears, 0:00:50.830 --> 0:00:54.310 and snouts, making them look sort of aerodynamic, if a 0:00:54.570 --> 0:00:58.700 tribble could look aerodynamic. They measure around just 5 to 0:00:58.700 --> 0:01:02.320 7 inches in length, that's 13 to 18 centimeters. They 0:01:02.340 --> 0:01:05.200 burrow under the snow in winter, eat tough plants that 0:01:05.260 --> 0:01:08.660 grind down their continuously growing teeth, and provide a food 0:01:08.720 --> 0:01:13.670 source for predators like arctic foxes and snowy owls. Lemmings 0:01:13.770 --> 0:01:17.030 migrate when food becomes scarce and can even swim across 0:01:17.090 --> 0:01:21.090 rivers and lakes when necessary. They also have a reputation 0:01:21.190 --> 0:01:25.259 for being extremely aggressive. Rather than running away from a predator, 0:01:25.280 --> 0:01:28.979 they'll often charge their attacker. They've even been known to 0:01:29.020 --> 0:01:32.800 attack humans who are studying lemmings and are working sled dogs. 0:01:33.860 --> 0:01:36.590 If you look up photos of lemmings, you'll inevitably find 0:01:36.650 --> 0:01:39.570 images where the lemming in question is baring its long 0:01:39.630 --> 0:01:43.890 front teeth and apparently screaming at the camera. Or squeaking, anyway. 0:01:44.770 --> 0:01:47.520 All of which is impressive for something that resembles a 0:01:47.720 --> 0:01:52.910 slightly shrimpy guinea pig. So why would these little creatures, 0:01:53.190 --> 0:01:55.630 interested in preserving life and limb to the point that 0:01:55.650 --> 0:01:58.030 they would fight a human or a weasel rather than 0:01:58.070 --> 0:02:02.370 be eaten, also jump off of cliffs? The truth is, 0:02:02.630 --> 0:02:07.090 this reputation is a myth. For the article this episode 0:02:07.130 --> 0:02:10.989 is based on, HowStuffWorks spoke via email with Rolf Anka Eames, 0:02:11.230 --> 0:02:13.930 a researcher in the Department of Arctic and Marine Biology 0:02:14.030 --> 0:02:18.380 at the Arctic University of Norway. He said, This idea 0:02:18.460 --> 0:02:22.000 stems from the migrations observed in one lemming species, the 0:02:22.060 --> 0:02:25.750 Norwegian lemming. During the peak years of this species, a 0:02:25.810 --> 0:02:28.830 large number of individuals migrate out of their normal habitat 0:02:29.130 --> 0:02:33.390 and die in large numbers. It's unclear what causes these migrations, 0:02:33.650 --> 0:02:38.240 but social stress, food shortage, or predators are candidates. Suicide 0:02:38.380 --> 0:02:43.480 is not a good explanation. The lemming suicide myth was 0:02:43.620 --> 0:02:48.530 popularized in a 1958 documentary segment from Disney with documentary 0:02:48.620 --> 0:02:52.670 and heavy scare quotes called White Wilderness, which claimed that 0:02:52.690 --> 0:02:56.370 this happens once every decade or so in response to overpopulation. 0:02:57.570 --> 0:03:00.330 Footage in the segment shows a few dozen lemmings running 0:03:00.370 --> 0:03:03.550 across the snow and falling from a cliff into water 0:03:03.730 --> 0:03:08.240 to their apparent deaths, accompanied by narration saying, a kind 0:03:08.280 --> 0:03:12.400 of compulsion seizes each tiny rodent, and, carried along by 0:03:12.440 --> 0:03:16.090 an unreasoning hysteria, each falls into step for a march 0:03:16.150 --> 0:03:19.769 that will take them to a strange destiny. That destiny 0:03:19.910 --> 0:03:25.030 is to jump into the ocean. But future investigations have 0:03:25.090 --> 0:03:28.490 shown that these scenes were faked. The lemmings they filmed 0:03:28.610 --> 0:03:30.830 aren't even native to the area of Alberta where the 0:03:30.850 --> 0:03:35.250 footage was shot. Allegedly, the segment's producers imported a group 0:03:35.290 --> 0:03:38.530 of the rodents and then used tight angles, misleading editing, 0:03:39.050 --> 0:03:41.630 and a good shove to get their dramatic footage of 0:03:41.930 --> 0:03:48.500 quote-unquote lemming suicide. Which, if true, is horrible. But it 0:03:48.530 --> 0:03:52.260 convinced so many people that 60 years later, zoologists still 0:03:52.280 --> 0:03:55.560 get asked whether it's true. But it's just a myth 0:03:55.820 --> 0:04:01.210 with a weird tiny kernel of truth. Lemmings do go 0:04:01.250 --> 0:04:04.490 through population cycles with highs and lows every few years. 0:04:05.170 --> 0:04:08.770 Some species, like the Norwegian lemming, are known to disperse 0:04:08.950 --> 0:04:12.510 or migrate in large numbers when booms in populations lead 0:04:12.570 --> 0:04:17.440 to food or personal space becoming scarce. This mass dispersal 0:04:17.500 --> 0:04:20.820 can sometimes lead to confused buildups on the banks of 0:04:20.839 --> 0:04:24.839 a body of water. Lemmings are good swimmers for short stints, 0:04:25.200 --> 0:04:28.120 but if their coat gets soaked through, they can accidentally 0:04:28.180 --> 0:04:33.409 drown or get too cold to recover. So deaths can happen, 0:04:33.990 --> 0:04:36.890 even lots of them at a time, but it's not 0:04:37.070 --> 0:04:41.870 purposeful or even particularly hysterical behavior, just an attempt to 0:04:41.910 --> 0:04:46.970 alleviate immediate stress. There's also a tall tale that lemmings 0:04:47.029 --> 0:04:51.289 can literally explode from anger, which, of course, they can't, 0:04:51.670 --> 0:04:54.060 though they are well known to leap and shriek at 0:04:54.100 --> 0:04:59.460 intruders to their habitats. A lemming's supposed mindless behavior and 0:04:59.520 --> 0:05:02.869 propensity for explosion are were both factors in a series 0:05:02.910 --> 0:05:06.390 of video games called Lemmings, the first of which debuted 0:05:06.470 --> 0:05:09.450 in 1991 for the Amiga PC, developed by the studio 0:05:09.529 --> 0:05:13.780 DMA Design, which has since become Rockstar North. In these, 0:05:14.060 --> 0:05:18.839 albeit non-realistic, puzzle games, the player guides groups of anthropomorphized Lemmings, 0:05:19.100 --> 0:05:21.760 each sporting green hair and a blue robe, to safety 0:05:21.900 --> 0:05:26.310 through various environments and obstacles. The Lemmings did often fall 0:05:26.370 --> 0:05:28.690 off of cliffs, and if you ran out of time 0:05:28.750 --> 0:05:31.060 on a given level, any that hadn't reached the end 0:05:31.320 --> 0:05:35.460 would explode. We should say here that people have been 0:05:35.520 --> 0:05:38.940 observing lemmings' behavior and population cycles with a sort of 0:05:39.260 --> 0:05:43.740 amused bewilderment for centuries. Going back to the 1500s, there 0:05:43.779 --> 0:05:47.500 are descriptions out of Scandinavia of lemmings pouring down from 0:05:47.520 --> 0:05:51.669 the sky during rainstorms. This is probably based on the 0:05:51.710 --> 0:05:54.690 reality that in the summer, when the weather turns and 0:05:54.710 --> 0:05:59.099 the snows melt, lemmings' winter burrows disintegrate around them, leaving 0:05:59.120 --> 0:06:02.400 a perhaps surprising number of the rodents exposed for the 0:06:02.440 --> 0:06:07.179 first time in several months. We'll get into what lemmings 0:06:07.360 --> 0:06:10.160 are really like in a minute, but first we're going 0:06:10.200 --> 0:06:20.290 to get into a quick word from our sponsor. In reality, lemmings, 0:06:20.589 --> 0:06:25.130 all 20 or so species, are just slightly unusual rodents. 0:06:26.250 --> 0:06:28.810 Depending on the species, they may burrow underground in the 0:06:28.850 --> 0:06:31.440 summer if the ground is warm enough to not be frozen. 0:06:32.720 --> 0:06:35.219 They typically make burrows in the snow during the winter, 0:06:35.779 --> 0:06:39.260 constructing nests underneath the blanket on the ground surface from 0:06:39.339 --> 0:06:44.210 whatever grasses, mosses, feathers, and fur they can find. Snow 0:06:44.250 --> 0:06:47.690 is actually a great insulator. Heat from the earth below 0:06:47.810 --> 0:06:50.890 trapped by snow can keep the ground just above freezing, 0:06:51.410 --> 0:06:54.349 creating a sort of shallow pocket along the ground called 0:06:54.390 --> 0:06:59.110 a subnivian zone. So, these rodents can access food and 0:06:59.190 --> 0:07:02.810 keep cozy in the cold, and visually hidden from predators 0:07:02.930 --> 0:07:07.310 looking for a snack. Sharp-eared predators can still hear them 0:07:07.390 --> 0:07:11.620 under the snow and pounce to break through, though. During 0:07:11.640 --> 0:07:14.260 the lemming's breeding season, which can be in the summer, 0:07:14.360 --> 0:07:17.679 the winter, or both, a female lemming might have multiple 0:07:17.720 --> 0:07:21.360 litters of multiple young, up to 13 per litter, which 0:07:21.480 --> 0:07:26.220 helps them proliferate during boom years. Different species of lemmings 0:07:26.320 --> 0:07:28.860 have coats of different colors to help them blend into 0:07:28.900 --> 0:07:32.530 their environments, from whites to grays and creams to browns, 0:07:33.010 --> 0:07:36.250 often with a lighter belly and a darker back. Some 0:07:36.290 --> 0:07:39.210 have coats that will lighten or even completely whiten during 0:07:39.230 --> 0:07:42.890 the winter to match the snow. But the Norway lemming 0:07:42.990 --> 0:07:48.350 has a famously immodest coat, incorporating mottled golds, reds, black 0:07:48.410 --> 0:07:51.750 and white, like a calico cat. It does help them 0:07:51.790 --> 0:07:54.390 blend in with local rocks and grasses during the summer, 0:07:54.960 --> 0:07:58.430 but it doesn't lighten over the winter. However, if they 0:07:58.470 --> 0:08:02.030 build out their snowy burrows successfully, they might just not 0:08:02.090 --> 0:08:05.650 need camouflage because they don't often surface during that time. 0:08:07.230 --> 0:08:11.440 Most lemmings are herbivores, eating grasses, sedges, mosses, and lichens, 0:08:11.760 --> 0:08:15.060 but some species will branch out to consuming snails, slugs, 0:08:15.140 --> 0:08:18.760 and other invertebrates. They live only a couple of years 0:08:18.800 --> 0:08:22.450 in the wild, but they're keystone species in their environments. 0:08:23.460 --> 0:08:26.900 Eames said, Lemmings are very important to the functioning of 0:08:26.980 --> 0:08:30.780 Arctic ecosystems. Their cycles are necessary for the maintenance of 0:08:30.880 --> 0:08:35.290 Arctic biodiversity through their role as prey and grazers of plants. 0:08:37.530 --> 0:08:42.090 In an ecosystem, populations of specific species may fluctuate drastically 0:08:42.270 --> 0:08:46.120 over a predictable period of time. Population cycles happen in 0:08:46.200 --> 0:08:49.380 ecosystems all over the world, and rodents are a common 0:08:49.440 --> 0:08:53.550 group of animals to experience population cycles. These cycles can 0:08:53.580 --> 0:08:58.760 be driven by disease, food availability, and predation. Lemming populations 0:08:58.960 --> 0:09:03.319 spike every few years, sometimes up to a thousandfold. This 0:09:03.380 --> 0:09:06.400 happens about every three to five years, though not like 0:09:06.580 --> 0:09:11.890 clockwork as with some other population cycling species. However, when 0:09:11.910 --> 0:09:14.750 they do, all of the predators on the tundra that 0:09:14.770 --> 0:09:18.090 depend on lemmings for food, like arctic foxes, hawks, and 0:09:18.150 --> 0:09:22.090 coastal birds called long-tailed jaegers, will eat very well that year. 0:09:23.160 --> 0:09:26.690 They're thus more fit to reproduce. Some animals, like the Jaegers, 0:09:26.790 --> 0:09:29.470 will actually choose whether to breed or not in any 0:09:29.510 --> 0:09:33.590 given year based on lemming availability. The rodents make excellent 0:09:33.630 --> 0:09:38.070 food for their young. High lemming populations also create lots 0:09:38.110 --> 0:09:41.590 of droppings, which feed the growth of vegetation. And they 0:09:41.630 --> 0:09:45.750 can also affect the reproduction of other prey species. For example, 0:09:45.960 --> 0:09:48.819 if Arctic foxes fill up on lemmings, they might not 0:09:48.920 --> 0:09:52.270 steal quite so many snow goose eggs that year. leading 0:09:52.360 --> 0:09:55.860 to a flux in the goose population the next year. Though, 0:09:56.000 --> 0:09:58.160 of course, since there will also be more foxes the 0:09:58.200 --> 0:10:03.120 next year, the cycle continues. Population spikes in lemmings can 0:10:03.160 --> 0:10:06.740 also be pretty destructive. During the summer months, lemmings eat 0:10:06.880 --> 0:10:10.179 lots of living vegetation. And when lemming populations are at 0:10:10.200 --> 0:10:13.110 their peak, the rodents eat so much that they have 0:10:13.120 --> 0:10:15.970 to travel across the tundra in great numbers in search 0:10:16.030 --> 0:10:22.250 of greener pastures. These migrations are unusual, too. During these years, 0:10:22.510 --> 0:10:25.970 lemmings eat so much that the results are noticeable from space, 0:10:26.490 --> 0:10:30.150 and the plants can take years to recover. Although it 0:10:30.230 --> 0:10:33.190 might seem detrimental to the ecosystem to have the vegetation 0:10:33.210 --> 0:10:36.610 of the tundra so destroyed at regular intervals, research has 0:10:36.670 --> 0:10:39.550 found that when you exclude lemmings from the system, the 0:10:39.570 --> 0:10:44.010 plant life actually suffers over time. There's been a lot 0:10:44.050 --> 0:10:47.710 of research into these population cycles, what causes them, and 0:10:47.790 --> 0:10:50.490 what effects they have over the long and short term. 0:10:51.230 --> 0:10:54.450 I understand that it's something of a heated topic among ecologists. 0:10:55.460 --> 0:10:59.060 Eames said, The main hypotheses about the population cycles in 0:10:59.100 --> 0:11:03.620 lemmings postulate that they result from interaction between predators, foxes, weasels, 0:11:03.660 --> 0:11:07.459 and raptors, and the lemmings themselves, or between plants and 0:11:07.500 --> 0:11:11.640 the lemmings that eat them. Predator-prey cycles have presently the 0:11:11.679 --> 0:11:15.599 most support. The irregularity in the dynamics is likely to 0:11:15.640 --> 0:11:22.030 be due to disruption from climate variability and change. Lemmings 0:11:22.130 --> 0:11:26.189 have been identified as a group particularly vulnerable to shifting climates. 0:11:26.870 --> 0:11:30.440 Because lemmings depend on cold winters in their tundra habitats, 0:11:30.840 --> 0:11:34.800 climate change is creating major problems for these important Arctic residents. 0:11:35.929 --> 0:11:38.830 As we said earlier, lemmings often build burrows in the deep, 0:11:38.910 --> 0:11:41.960 soft snow in the winter, nesting and finding food along 0:11:41.980 --> 0:11:45.960 the ground underneath in the subnivian zone. When winter temperatures 0:11:46.000 --> 0:11:48.880 are just a bit warmer, harder packs of snow and 0:11:49.059 --> 0:11:51.640 ice can block lemmings from their food source and make 0:11:51.660 --> 0:11:56.059 it more difficult for them to dig out their shelters. Again, 0:11:56.300 --> 0:12:00.400 fluctuations of lemming populations are natural wherever these critters live, 0:12:00.860 --> 0:12:04.780 but researchers have been seeing more sporadic cycles, or longer 0:12:04.860 --> 0:12:08.469 periods between lemming peaks over the past 30 years or so. 0:12:09.550 --> 0:12:12.950 There's concern that climate change could be to blame, or 0:12:13.030 --> 0:12:15.630 that the warming climate could even lead to a collapse 0:12:15.730 --> 0:12:19.929 of the population cycle altogether, with new, permanently low lemming 0:12:19.970 --> 0:12:24.630 populations in some areas. With lemmings as a key intermediary 0:12:24.690 --> 0:12:27.990 between plant life and predator species, this could lead to 0:12:28.050 --> 0:12:32.190 changes in entire ecosystems, including the extinction of mammals and 0:12:32.250 --> 0:12:36.880 birds that depend on lemmings as a food source. Researchers 0:12:37.040 --> 0:12:40.360 are still looking into it. For all the myths around 0:12:40.440 --> 0:12:44.760 these tiny, cute, fierce critters, the reality is teaching us 0:12:44.800 --> 0:12:52.900 a lot about how ecosystems work. Today's episode is based 0:12:52.940 --> 0:12:55.880 on the article, Lemmings Jumping Off Cliffs in Mass is 0:12:55.950 --> 0:13:00.090 a Myth, on HowStuffWorks.com, written by Jessalyn Shields. BrainStuff is 0:13:00.110 --> 0:13:03.470 a production of iHeart Podcasts in partnership with HowStuffWorks.com and 0:13:03.510 --> 0:13:06.170 is produced by Tyler Klang. Of four more shows from 0:13:06.250 --> 0:13:09.829 iHeart Podcasts, visit the iHeart Radio app, Apple Podcasts, or 0:13:09.870 --> 0:13:11.670 wherever you listen to your favorite shows.