1 00:00:01,920 --> 00:00:06,440 Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey 2 00:00:06,519 --> 00:00:10,639 Speaker 1: brain Stuff, Lauren fog Obam. Here, during party conversation or 3 00:00:10,680 --> 00:00:12,719 Speaker 1: at a trivia night, you may have heard the fun 4 00:00:12,760 --> 00:00:15,640 Speaker 1: little fact that humans and bananas share fifty or even 5 00:00:15,720 --> 00:00:19,319 Speaker 1: six of the same DNA. There seems to be a 6 00:00:19,320 --> 00:00:21,400 Speaker 1: lot of differences, though, between a person and a piece 7 00:00:21,400 --> 00:00:23,439 Speaker 1: of yellow fruit, starting with the fact that one is 8 00:00:23,480 --> 00:00:26,000 Speaker 1: an animal and the other as a plant. But actually 9 00:00:26,040 --> 00:00:29,120 Speaker 1: there is some truth to that startling statistic, but it's 10 00:00:29,160 --> 00:00:32,520 Speaker 1: not the whole truth. This urban legend of sorts likely 11 00:00:32,560 --> 00:00:35,320 Speaker 1: originated from a program run by the National Human Genome 12 00:00:35,360 --> 00:00:39,519 Speaker 1: Research Institute back in although similar data may have been 13 00:00:39,560 --> 00:00:44,320 Speaker 1: run elsewhere. Genetics expert Dr Lawrence Brody and his colleagues 14 00:00:44,360 --> 00:00:47,800 Speaker 1: generated some banana human information to be included as part 15 00:00:47,880 --> 00:00:51,360 Speaker 1: of an educational Smithsonian Museum of Natural History video called 16 00:00:51,560 --> 00:00:55,720 Speaker 1: The Animated Genome. That video noted that DNA between a 17 00:00:55,840 --> 00:01:00,560 Speaker 1: human and a banana is forty one percent similar. In 18 00:01:00,640 --> 00:01:03,240 Speaker 1: order to find out how this similarity was determined, we 19 00:01:03,320 --> 00:01:07,240 Speaker 1: talked with Dr Brodie himself. He explained that first, it's 20 00:01:07,240 --> 00:01:11,000 Speaker 1: important to understand the difference between DNA and protein products. 21 00:01:11,640 --> 00:01:14,119 Speaker 1: You can think of DNA as the blueprint of a house, 22 00:01:14,480 --> 00:01:17,720 Speaker 1: and protein products as the actual house because all of 23 00:01:17,760 --> 00:01:21,759 Speaker 1: the information is in there. Then think of human DNA 24 00:01:21,840 --> 00:01:24,480 Speaker 1: as the blueprint for a ranch home, and banana DNA 25 00:01:24,640 --> 00:01:27,480 Speaker 1: is that of a condo. In each house, a bunch 26 00:01:27,480 --> 00:01:30,679 Speaker 1: of things are similar the plumbing, bathrooms, kitchen, but the 27 00:01:30,800 --> 00:01:33,800 Speaker 1: end products are both quite different. And that's how it 28 00:01:33,840 --> 00:01:36,800 Speaker 1: works with humans versus just about everything else from bananas 29 00:01:36,800 --> 00:01:40,360 Speaker 1: two chimpanzees. The second thing to keep in mind is 30 00:01:40,400 --> 00:01:43,160 Speaker 1: that genes, which are the regions of DNA that code 31 00:01:43,160 --> 00:01:45,880 Speaker 1: for these proteins, only make up about two per cent 32 00:01:46,040 --> 00:01:49,960 Speaker 1: of your DNA. In order to compare humans and bananas, 33 00:01:50,160 --> 00:01:52,480 Speaker 1: scientists first looked at the sequences of genes in a 34 00:01:52,520 --> 00:01:56,600 Speaker 1: typical banana gino. Brodie said. We then used these DNA 35 00:01:56,680 --> 00:01:59,640 Speaker 1: sequences to predict the amino acid sequence of all the 36 00:01:59,640 --> 00:02:02,480 Speaker 1: protein means that would be made from those genes. We 37 00:02:02,600 --> 00:02:06,640 Speaker 1: then did the same process for all human genes. All 38 00:02:06,680 --> 00:02:09,760 Speaker 1: of the protein sequences were placed in a file. Next, 39 00:02:09,880 --> 00:02:13,000 Speaker 1: the scientists compared the protein sequence from each banana gene 40 00:02:13,240 --> 00:02:18,079 Speaker 1: to every human gene. Brodie said. The program compares how 41 00:02:18,120 --> 00:02:20,679 Speaker 1: similar the sequence of the banana genes are to each 42 00:02:20,760 --> 00:02:24,360 Speaker 1: human gene. Program kept any matches that were more similar 43 00:02:24,360 --> 00:02:27,679 Speaker 1: than one would expect by chance. The program continued doing 44 00:02:27,680 --> 00:02:31,280 Speaker 1: this gene by gene. All told, more than four million 45 00:02:31,320 --> 00:02:34,959 Speaker 1: comparisons were done, resulting in about seven thousand best hits 46 00:02:35,040 --> 00:02:38,880 Speaker 1: between the two genomes. Then the percent similarity score for 47 00:02:38,919 --> 00:02:42,359 Speaker 1: each of those hits was averaged. Bertie said, this gave 48 00:02:42,440 --> 00:02:46,160 Speaker 1: us the result of about this is the average similarity 49 00:02:46,200 --> 00:02:51,360 Speaker 1: between proteins gene products, not genes. Gene products or proteins 50 00:02:51,360 --> 00:02:54,720 Speaker 1: are the biochemical material resulting from a gene becoming functional. 51 00:02:55,840 --> 00:02:59,320 Speaker 1: Brodie continued, Of course, there are many many genes in 52 00:02:59,320 --> 00:03:02,359 Speaker 1: our genome do not have a recognizable counterpart in the 53 00:03:02,400 --> 00:03:06,840 Speaker 1: banana genome, and vice versa. In case that's a bit 54 00:03:06,840 --> 00:03:10,919 Speaker 1: difficult to chew and swallow, let's break it down. Essentially, 55 00:03:11,040 --> 00:03:13,560 Speaker 1: they took all of the banana genes and compared them 56 00:03:13,639 --> 00:03:16,440 Speaker 1: one at a time to human genes. From that they 57 00:03:16,480 --> 00:03:19,440 Speaker 1: called a degree of similarity. If the banana had the 58 00:03:19,480 --> 00:03:22,560 Speaker 1: gene but the human didn't, that didn't get counted. And 59 00:03:22,680 --> 00:03:26,080 Speaker 1: about sixty of our genes have a recognizable counterpart in 60 00:03:26,080 --> 00:03:31,480 Speaker 1: the banana genome, Brodie explained. Of those, the proteins encoded 61 00:03:31,480 --> 00:03:34,960 Speaker 1: by them are roughly identical. When we compare the amino 62 00:03:35,000 --> 00:03:37,920 Speaker 1: acid sequence of the human protein to its equivalent in 63 00:03:38,080 --> 00:03:41,880 Speaker 1: the banana. It may seem shocking that so many genes 64 00:03:41,880 --> 00:03:44,000 Speaker 1: and so many of the proteins that they create are 65 00:03:44,080 --> 00:03:47,280 Speaker 1: similar in two such vastly different beings as a person 66 00:03:47,320 --> 00:03:50,080 Speaker 1: in a banana. But when you think about it, it's 67 00:03:50,200 --> 00:03:53,840 Speaker 1: not that shocking, Brodie explained. If you think about what 68 00:03:53,880 --> 00:03:56,640 Speaker 1: we do for living and what a banana does, there's 69 00:03:56,680 --> 00:03:58,480 Speaker 1: a lot of things we do the same way, like 70 00:03:58,560 --> 00:04:01,840 Speaker 1: consuming oxygen. A lot of those genes are just fundamental 71 00:04:01,920 --> 00:04:06,560 Speaker 1: to life. So when people repeat the percentages being a 72 00:04:06,600 --> 00:04:10,000 Speaker 1: similarity of DNA, actually what the research looked at was 73 00:04:10,040 --> 00:04:14,080 Speaker 1: the similarity of gene products, Brodie reassured us, it's a 74 00:04:14,120 --> 00:04:17,080 Speaker 1: pretty minor mistake. The kernel that you would take home 75 00:04:17,200 --> 00:04:19,120 Speaker 1: is that we have something in common with a banana 76 00:04:19,200 --> 00:04:22,440 Speaker 1: and a potato and a pine tree. That part is true. 77 00:04:23,040 --> 00:04:25,279 Speaker 1: The fine point about the gene products or the DNA, 78 00:04:25,680 --> 00:04:28,080 Speaker 1: it's easy to see how that would get translated incorrectly. 79 00:04:29,520 --> 00:04:31,839 Speaker 1: So a scientist looked at the DNA sequence of a 80 00:04:31,839 --> 00:04:34,000 Speaker 1: banana and compared it with the DNA of a human 81 00:04:34,320 --> 00:04:38,640 Speaker 1: it would not align. We also spoke via email with 82 00:04:38,720 --> 00:04:42,400 Speaker 1: Mike Francis, a PhD student in bioinformatics at the University 83 00:04:42,400 --> 00:04:46,279 Speaker 1: of Georgia. He explained, you share fifty of your DNA 84 00:04:46,360 --> 00:04:49,040 Speaker 1: with each of your parents, but with bananas, we share 85 00:04:49,080 --> 00:04:53,880 Speaker 1: about of our genes. As we said earlier, genes make 86 00:04:53,960 --> 00:04:57,320 Speaker 1: up just two of your DNA, So what's the other 87 00:04:58,200 --> 00:05:01,200 Speaker 1: made up of? Well eight percent of the rest of 88 00:05:01,240 --> 00:05:04,320 Speaker 1: your DNA regulates genes as to whether a gene should 89 00:05:04,360 --> 00:05:07,919 Speaker 1: be turned on or off. The other appears to have 90 00:05:08,080 --> 00:05:11,560 Speaker 1: unknown functions or functions that have been lost through evolution. 91 00:05:12,360 --> 00:05:15,919 Speaker 1: Francis said, these unknown sections of DNA used to commonly 92 00:05:15,960 --> 00:05:18,479 Speaker 1: be called junk DNA because it was thought to do nothing. 93 00:05:19,080 --> 00:05:21,440 Speaker 1: I hesitate to use the phrase junk DNA because each 94 00:05:21,520 --> 00:05:24,080 Speaker 1: year it seems we realize more of this junk is 95 00:05:24,080 --> 00:05:28,360 Speaker 1: actually functional. Humans don't just share a high percentage of 96 00:05:28,360 --> 00:05:32,440 Speaker 1: protein and coding genes with bananas. We also share of 97 00:05:32,440 --> 00:05:35,200 Speaker 1: those genes with a mouse, and we share sixty one 98 00:05:35,640 --> 00:05:39,080 Speaker 1: of disease causing genes with a fruit fly. Brodie said, 99 00:05:39,400 --> 00:05:42,240 Speaker 1: the remarkable thing is that despite being very far apart 100 00:05:42,279 --> 00:05:45,600 Speaker 1: in evolutionary time, we can still find a common signature 101 00:05:45,600 --> 00:05:48,839 Speaker 1: in the genome of a common ancestor. These are preserved 102 00:05:48,880 --> 00:05:51,200 Speaker 1: because the genome of an organism that lived billions of 103 00:05:51,279 --> 00:05:54,640 Speaker 1: years ago contained genes that helped cells live and reproduce. 104 00:05:55,160 --> 00:05:59,719 Speaker 1: Those same genes are preserved in us and plants. Francis 105 00:05:59,760 --> 00:06:02,320 Speaker 1: add that humans likely share about one percent of their 106 00:06:02,360 --> 00:06:05,680 Speaker 1: DNA with other fruits as well. He said this is 107 00:06:05,720 --> 00:06:08,000 Speaker 1: because all life that exists on Earth has evolved from 108 00:06:08,000 --> 00:06:10,839 Speaker 1: a single cell that originated about one point six billion 109 00:06:10,920 --> 00:06:19,560 Speaker 1: years ago. In a sense, we're all relatives. Today's episode 110 00:06:19,560 --> 00:06:21,760 Speaker 1: was written by Alia Hoyt and produced by Tyler Clay. 111 00:06:22,240 --> 00:06:24,960 Speaker 1: Brain Stuff is the production of iHeart Radio's How Stuff Works. 112 00:06:24,960 --> 00:06:26,479 Speaker 1: For more in this and lots of other topics that 113 00:06:26,520 --> 00:06:29,560 Speaker 1: are different but do similar things, visit our home planet 114 00:06:29,680 --> 00:06:32,280 Speaker 1: how stufe works dot com and for more podcasts from 115 00:06:32,279 --> 00:06:34,280 Speaker 1: my heart Radio, you can visit the I heart Radio app, 116 00:06:34,400 --> 00:06:37,080 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.