1 00:00:01,920 --> 00:00:06,960 Speaker 1: Welcome to Brainstuff production of iHeart Radio. Hey brain Stuff, 2 00:00:07,000 --> 00:00:12,559 Speaker 1: Lauren bobble bomb here. You may have noticed that although dragonflies, bats, 3 00:00:12,680 --> 00:00:16,480 Speaker 1: and say California condors all have the ability to fly, 4 00:00:17,000 --> 00:00:20,560 Speaker 1: they aren't very similar in any other way. It's not 5 00:00:20,760 --> 00:00:23,360 Speaker 1: very likely that any of these animals had a common 6 00:00:23,400 --> 00:00:26,720 Speaker 1: ancestor any time in the past six million years or so, 7 00:00:27,120 --> 00:00:30,960 Speaker 1: and definitely not one particular shared ancestor that first figured 8 00:00:30,960 --> 00:00:33,159 Speaker 1: out how to haul its body off the ground and 9 00:00:33,280 --> 00:00:37,080 Speaker 1: zoom around in the air. And yet they all developed 10 00:00:37,120 --> 00:00:41,000 Speaker 1: the ability to fly separately. This is an example of 11 00:00:41,000 --> 00:00:47,159 Speaker 1: what scientists call convergent evolution. Evolution doesn't do things on purpose. 12 00:00:47,360 --> 00:00:49,720 Speaker 1: It's not sitting at a big desk in a corner 13 00:00:49,760 --> 00:00:53,440 Speaker 1: office somewhere making decisions about which animals lay eggs or 14 00:00:53,520 --> 00:00:57,120 Speaker 1: get pouches on their tummies. Evolution is the process of 15 00:00:57,240 --> 00:01:00,560 Speaker 1: organisms changing over the course of many generation sans to 16 00:01:00,720 --> 00:01:04,440 Speaker 1: suit the conditions under which they live, and some traits 17 00:01:04,520 --> 00:01:08,080 Speaker 1: like flying, are particularly useful. It can help you catch 18 00:01:08,120 --> 00:01:11,520 Speaker 1: prey or avoid predators, or easily moved to new food 19 00:01:11,560 --> 00:01:16,240 Speaker 1: sources and ecological niches. So it's evolved separately in different 20 00:01:16,240 --> 00:01:21,200 Speaker 1: groups of animals. Several times. However, flying doesn't look the 21 00:01:21,240 --> 00:01:25,560 Speaker 1: same across the groups. For instance, bats developed a membrane 22 00:01:25,600 --> 00:01:29,479 Speaker 1: between their abdomen, arms and fingers to catch air, while 23 00:01:29,520 --> 00:01:33,720 Speaker 1: birds sprouted feathers along a finger fused fore limb, which 24 00:01:33,920 --> 00:01:37,480 Speaker 1: means bats can maneuver their wings separately, while birds have 25 00:01:37,600 --> 00:01:41,280 Speaker 1: to move together. Flying insects just fashioned wings out of 26 00:01:41,280 --> 00:01:46,520 Speaker 1: their exo skeletons. So convergent evolution can tell us a 27 00:01:46,560 --> 00:01:49,960 Speaker 1: lot about what kinds of adaptions work to help species 28 00:01:49,960 --> 00:01:53,160 Speaker 1: survive all the trials and tribulations they might face in 29 00:01:53,160 --> 00:01:57,240 Speaker 1: a particular type of environment, but what ecologists call a biome. 30 00:01:58,120 --> 00:02:01,680 Speaker 1: For instance, in North America, the kangaroo rat lives in 31 00:02:01,720 --> 00:02:04,840 Speaker 1: the Sonoran Desert, where it spends the scorching days in 32 00:02:04,880 --> 00:02:09,560 Speaker 1: a cool, dry burrow and the cool desert nights collecting seeds, vegetation, 33 00:02:09,760 --> 00:02:13,400 Speaker 1: and the occasional insect if they can get it. Everybody 34 00:02:13,440 --> 00:02:18,359 Speaker 1: in the desert wants to eat them coyotes, bobcats, rattlesnakes, owls, 35 00:02:18,360 --> 00:02:22,280 Speaker 1: But the kangaroo rat is fast and agile, with powerful 36 00:02:22,280 --> 00:02:25,880 Speaker 1: back legs and extremely sensitive hearing, all of which helps 37 00:02:25,880 --> 00:02:28,959 Speaker 1: it survive a hard scrabble bottom of the food chain. 38 00:02:29,080 --> 00:02:33,960 Speaker 1: Desert biome lifestyle, and although the kangaroo rat doesn't have 39 00:02:34,080 --> 00:02:38,960 Speaker 1: an enviable life, it is effective to other rodents on Earth. 40 00:02:39,400 --> 00:02:42,800 Speaker 1: The Australian hopping mouse in the Australian Outback and a 41 00:02:42,840 --> 00:02:45,720 Speaker 1: species called the jerboah in the deserts of North Africa, 42 00:02:45,880 --> 00:02:50,600 Speaker 1: Asia and the Middle East evolved separately and yet incredibly similarly. 43 00:02:52,360 --> 00:02:56,720 Speaker 1: But how does convergent evolution happen? This is a trickier question, 44 00:02:57,080 --> 00:02:59,600 Speaker 1: and the development of genetic tools over the past twenty 45 00:02:59,680 --> 00:03:02,880 Speaker 1: years has been helpful in picking it apart. In a 46 00:03:02,919 --> 00:03:06,080 Speaker 1: twenty nineteen study published in the journal Science, a group 47 00:03:06,120 --> 00:03:09,240 Speaker 1: of researchers at Harvard University looked at the development of 48 00:03:09,280 --> 00:03:13,200 Speaker 1: flightlessness and birds, a trait that's evolved several times over, 49 00:03:13,760 --> 00:03:17,480 Speaker 1: and exactly how evolution pulled it off in penguins in 50 00:03:17,520 --> 00:03:21,840 Speaker 1: the same way that it did in ostriches. Flightless birds 51 00:03:21,960 --> 00:03:26,240 Speaker 1: or rattites can't fly for a couple of reasons. Somewhere 52 00:03:26,280 --> 00:03:29,760 Speaker 1: along their lineage, they have lost their keel, the bone 53 00:03:29,800 --> 00:03:32,880 Speaker 1: that runs perpendicular to the breastbone on flying birds that 54 00:03:32,960 --> 00:03:37,440 Speaker 1: the pictorial muscles attached to, and they have reduced four 55 00:03:37,520 --> 00:03:41,200 Speaker 1: limbs arranging from nearly absent in the Kiwi bird, to 56 00:03:41,520 --> 00:03:46,120 Speaker 1: still obvious but reduced in size in the ostrich However, 57 00:03:46,560 --> 00:03:50,200 Speaker 1: there are many ways the particular convergent traits can evolve. 58 00:03:51,320 --> 00:03:55,080 Speaker 1: We spoke with Tim Sackton, director of bionformatics at Harvard. 59 00:03:55,760 --> 00:03:59,560 Speaker 1: He said, before genomics, one could use developmental tools to 60 00:03:59,640 --> 00:04:03,240 Speaker 1: figure out if the same or different developmental mechanisms seemed 61 00:04:03,280 --> 00:04:07,240 Speaker 1: to be involved in convergent phenotypes. But the idea of 62 00:04:07,400 --> 00:04:11,440 Speaker 1: levels of convergence same mutation, same gene or same pathway 63 00:04:11,840 --> 00:04:15,000 Speaker 1: has developed in large part because it's possible to look 64 00:04:15,080 --> 00:04:18,360 Speaker 1: in the genome for these things now. In the rabbites, 65 00:04:18,440 --> 00:04:20,960 Speaker 1: for example, we were able to show that the same 66 00:04:21,120 --> 00:04:24,600 Speaker 1: regions of the genome the control where and when certain 67 00:04:24,640 --> 00:04:29,279 Speaker 1: genes are expressed, are repeatedly evolving in flightless birds. But 68 00:04:29,440 --> 00:04:35,719 Speaker 1: this doesn't seem to involve the same nucleotide mutations. And yes, 69 00:04:35,760 --> 00:04:39,080 Speaker 1: where some traits converge from completely different corners of the 70 00:04:39,120 --> 00:04:43,839 Speaker 1: living world, the opposite is also true. Divergent evolution is 71 00:04:43,880 --> 00:04:47,360 Speaker 1: the process by which groups from one species or organism 72 00:04:47,400 --> 00:04:51,680 Speaker 1: begin to develop different traits, thereby splitting in two separate species. 73 00:04:52,440 --> 00:04:56,680 Speaker 1: This often happens when populations of a species are separated geographically, 74 00:04:57,120 --> 00:04:59,760 Speaker 1: and over time they adapt to the conditions of their 75 00:04:59,800 --> 00:05:03,600 Speaker 1: new spot, whether it's increased predation pressures or a change 76 00:05:03,600 --> 00:05:08,480 Speaker 1: in climate. One famous example of divergent evolution was found 77 00:05:08,520 --> 00:05:11,600 Speaker 1: by Charles Darwin and has travels to the Galapagos Islands 78 00:05:11,600 --> 00:05:15,280 Speaker 1: in eight thirty six. Darwin's finches, as they're now known, 79 00:05:15,520 --> 00:05:18,240 Speaker 1: were a group of tanagers, which are not true finches, 80 00:05:18,520 --> 00:05:21,880 Speaker 1: that lived on different islands in the archipelago, the main 81 00:05:21,920 --> 00:05:25,239 Speaker 1: difference between them being the shape of their beaks, which 82 00:05:25,320 --> 00:05:28,720 Speaker 1: changed over the generations due to the particular foods available 83 00:05:28,760 --> 00:05:33,240 Speaker 1: to the birds on the different islands. And one more 84 00:05:33,279 --> 00:05:38,839 Speaker 1: example fingerprints. Most non human animals don't have them, except 85 00:05:38,880 --> 00:05:42,719 Speaker 1: for close human relatives such as chimps and gorillas, but 86 00:05:43,120 --> 00:05:47,640 Speaker 1: koalas have fingerprints to The fascinating thing about human and 87 00:05:47,680 --> 00:05:51,360 Speaker 1: koala prints is that, even though they're almost identical, they 88 00:05:51,360 --> 00:06:00,080 Speaker 1: seem to have evolved independently. Today's episode was written by 89 00:06:00,160 --> 00:06:02,920 Speaker 1: Jescelin Shields and produced by Tyler Clang. For more on 90 00:06:03,000 --> 00:06:06,360 Speaker 1: this and lots of other converging and diverging topics, visit 91 00:06:06,400 --> 00:06:08,960 Speaker 1: how stuff works dot com. Brain Stuff is a production 92 00:06:09,000 --> 00:06:11,520 Speaker 1: of iHeart Radio or more podcasts in my heart Radio, 93 00:06:11,720 --> 00:06:14,479 Speaker 1: visit the iHeart Radio app, Apple podcasts, or wherever you 94 00:06:14,520 --> 00:06:15,800 Speaker 1: listen to your favorite shows.