1 00:00:02,960 --> 00:00:08,280 Speaker 1: Welcome to Stuff to Blow Your Mind production of iHeartRadio. Hello, 2 00:00:08,320 --> 00:00:11,280 Speaker 1: and welcome to Stuff to Blow Your Mind the listener mail. 3 00:00:11,880 --> 00:00:14,760 Speaker 1: My name is Joe McCormick. My regular co host Robert 4 00:00:14,840 --> 00:00:18,160 Speaker 1: Lamb is out today, so I'm trekking on my own 5 00:00:18,239 --> 00:00:22,079 Speaker 1: once again, with none but Carney the mailbot at my side. 6 00:00:22,200 --> 00:00:24,560 Speaker 1: But Rob is going to be back with me soon. 7 00:00:25,360 --> 00:00:28,480 Speaker 1: We're going to have a vault episode for you tomorrow. 8 00:00:28,720 --> 00:00:31,360 Speaker 1: That's going to be Tuesday, and then there should be 9 00:00:31,400 --> 00:00:34,159 Speaker 1: an all new short form on Wednesday and a new 10 00:00:34,240 --> 00:00:37,640 Speaker 1: core episode with Rob and me back together on Thursday 11 00:00:37,720 --> 00:00:41,240 Speaker 1: of this week. All right, I guess we should jump 12 00:00:41,320 --> 00:00:44,920 Speaker 1: right into the messages. This first message is from Vic. 13 00:00:50,120 --> 00:00:53,720 Speaker 1: She says, Hi, Robert and Joe. I love your podcast. 14 00:00:53,800 --> 00:00:56,040 Speaker 1: I was hooked after I listened to the multi part 15 00:00:56,040 --> 00:00:59,040 Speaker 1: episode on mirrors, but my favorite of all time is 16 00:00:59,080 --> 00:01:03,280 Speaker 1: the history of the odometer, absolutely blew my mind. For 17 00:01:03,440 --> 00:01:07,160 Speaker 1: my question or possible show suggestion, do you know any 18 00:01:07,240 --> 00:01:11,400 Speaker 1: theories on why humans evolved away from having thick fur 19 00:01:11,720 --> 00:01:14,880 Speaker 1: or hair like that of our closest living relatives in 20 00:01:14,920 --> 00:01:18,080 Speaker 1: the Great Ape family. I heard somewhere recently that humans 21 00:01:18,120 --> 00:01:21,360 Speaker 1: actually have the same amount of hair on average as 22 00:01:21,400 --> 00:01:25,600 Speaker 1: a chimpanzee. But human body hair is so fine and 23 00:01:25,800 --> 00:01:28,600 Speaker 1: or short for the most part that it doesn't appear 24 00:01:28,640 --> 00:01:30,920 Speaker 1: to be fur. I don't know if this is true. 25 00:01:31,000 --> 00:01:33,840 Speaker 1: I had a good laugh wondering if our early ancestors 26 00:01:33,880 --> 00:01:38,080 Speaker 1: started wearing coverings while they still had thick coats, and 27 00:01:38,200 --> 00:01:42,000 Speaker 1: my brain started playing Planet of the Apes. Maybe there 28 00:01:42,000 --> 00:01:44,840 Speaker 1: are advantages to our naked mole rat status in the 29 00:01:44,840 --> 00:01:48,080 Speaker 1: great ape family, maybe something about fleas lice and other 30 00:01:48,160 --> 00:01:51,200 Speaker 1: fur loving pests. Sorry for the long email, would love 31 00:01:51,240 --> 00:01:52,960 Speaker 1: to know what you think. Thank you for all the 32 00:01:53,000 --> 00:01:56,880 Speaker 1: great shows, Vic. Thank you for the message. Vic. Now, 33 00:01:56,920 --> 00:02:01,000 Speaker 1: initially I did not know the answer to your question 34 00:02:01,200 --> 00:02:06,160 Speaker 1: about hair follical density and hair thickness in humans versus chimpanzees. 35 00:02:06,320 --> 00:02:10,760 Speaker 1: But interesting thing in trying to answer your other question, 36 00:02:11,200 --> 00:02:13,519 Speaker 1: I came across an answer to that one too, So 37 00:02:13,560 --> 00:02:16,520 Speaker 1: more on that in a bit. But the main question here, 38 00:02:16,880 --> 00:02:20,520 Speaker 1: how did humans come to be relatively hairless compared to 39 00:02:20,560 --> 00:02:23,919 Speaker 1: our nearest relatives in the animal kingdom. This is a 40 00:02:23,960 --> 00:02:26,520 Speaker 1: really interesting question and one we've looked at on the 41 00:02:26,520 --> 00:02:29,200 Speaker 1: show before, so I just did a little reviewing to 42 00:02:29,680 --> 00:02:32,600 Speaker 1: refresh myself on it. So we don't know for sure. 43 00:02:32,680 --> 00:02:35,000 Speaker 1: With a lot of these evolutionary questions, we can come 44 00:02:35,080 --> 00:02:37,839 Speaker 1: up with good guesses at the answer, but sometimes it's 45 00:02:37,840 --> 00:02:41,840 Speaker 1: hard to know for certain what the actual reasoning or 46 00:02:41,880 --> 00:02:46,239 Speaker 1: pressure driving and adaptation in the distant past was. But 47 00:02:47,240 --> 00:02:49,919 Speaker 1: I think there are some pretty good guesses about what 48 00:02:50,040 --> 00:02:54,080 Speaker 1: drove the human adaptation for comparative nakedness. One thing to 49 00:02:54,160 --> 00:02:58,120 Speaker 1: note starting off is that although we are relatively hairless 50 00:02:58,200 --> 00:03:01,839 Speaker 1: overall compared to most st other mammals, there's a fair 51 00:03:01,840 --> 00:03:04,600 Speaker 1: amount of variation in the amount of body hair present 52 00:03:04,680 --> 00:03:08,320 Speaker 1: on humans, like in between different human individuals, and I 53 00:03:08,360 --> 00:03:11,160 Speaker 1: think it's interesting that there are pretty consistent patterns of 54 00:03:11,280 --> 00:03:15,520 Speaker 1: hairiness versus hairlessness on different regions of the body that 55 00:03:15,560 --> 00:03:18,720 Speaker 1: are common to almost all people. So, for example, we 56 00:03:18,800 --> 00:03:21,400 Speaker 1: don't grow hair on the palms of our hands or 57 00:03:21,440 --> 00:03:23,839 Speaker 1: the soles of our feet for the most part. Though 58 00:03:23,880 --> 00:03:28,080 Speaker 1: if you look, these skin surface patterns are somewhat shared 59 00:03:28,440 --> 00:03:34,200 Speaker 1: by our closest relatives, even the very hairy ones. So chimpanzees, gorillas, 60 00:03:34,240 --> 00:03:38,360 Speaker 1: and other great apes also don't have fur on their palms, 61 00:03:38,440 --> 00:03:41,360 Speaker 1: and this is probably all for the same reason. In 62 00:03:41,720 --> 00:03:44,440 Speaker 1: all of us. It's so that we can have improved 63 00:03:44,520 --> 00:03:48,240 Speaker 1: grip and dexterity. Imagine trying to grip a tree branch, 64 00:03:48,320 --> 00:03:50,320 Speaker 1: to climb a tree, or swing from a tree branch, 65 00:03:50,800 --> 00:03:54,240 Speaker 1: or to manipulate objects in your hands. If those hands 66 00:03:54,240 --> 00:03:56,760 Speaker 1: were covered in fur, things would really kind of slide 67 00:03:56,760 --> 00:03:59,840 Speaker 1: around in there, it seems. However, when it comes to 68 00:04:00,200 --> 00:04:03,880 Speaker 1: the general loss of over the covering the whole body, 69 00:04:04,120 --> 00:04:08,160 Speaker 1: one of the major explanations is that it has to 70 00:04:08,200 --> 00:04:13,800 Speaker 1: do with thermoregulation, the ability to manage the body's internal temperature. 71 00:04:14,480 --> 00:04:18,120 Speaker 1: Fur helps insulate the body against the cold. It's very 72 00:04:18,200 --> 00:04:21,000 Speaker 1: useful for that, and many mammals use it to that end, 73 00:04:21,480 --> 00:04:25,880 Speaker 1: but as an insulation method it's inflexible. A mammal with 74 00:04:26,040 --> 00:04:30,360 Speaker 1: thick fur can't quickly take its fur off when it 75 00:04:30,400 --> 00:04:33,520 Speaker 1: gets hot, so it has to be careful to avoid, say, 76 00:04:33,600 --> 00:04:38,400 Speaker 1: overexerting itself out in the sun. And the thermoregulation hypothesis 77 00:04:38,440 --> 00:04:42,040 Speaker 1: says well, human ancestors, by losing most of their body 78 00:04:42,080 --> 00:04:47,400 Speaker 1: hair massively increased their ability to cool the body, especially 79 00:04:47,520 --> 00:04:51,640 Speaker 1: during exercise in hot climates, maybe under the direct sun. 80 00:04:52,720 --> 00:04:56,480 Speaker 1: And I think one thing that makes the thermoregulation hypothesis 81 00:04:56,600 --> 00:05:00,599 Speaker 1: strong is that the loss of body hair is the 82 00:05:00,640 --> 00:05:05,400 Speaker 1: only observed genetic change that would serve this purpose. In fact, 83 00:05:05,440 --> 00:05:08,159 Speaker 1: you can see other signs that there was intense pressure 84 00:05:08,160 --> 00:05:12,240 Speaker 1: on human ancestors to develop genetic adaptations for cooling the body. 85 00:05:12,400 --> 00:05:16,760 Speaker 1: And a big example here is sweat glands. So if 86 00:05:16,760 --> 00:05:19,440 Speaker 1: I asked you to think what distinguishes us from our 87 00:05:19,480 --> 00:05:22,640 Speaker 1: closest relatives like chimpanzees, what are some body differences you 88 00:05:22,640 --> 00:05:26,080 Speaker 1: can think of? You might think of things like bipedal locomotion. 89 00:05:26,240 --> 00:05:29,200 Speaker 1: We tend to walk upright on two legs, the relative 90 00:05:29,279 --> 00:05:32,480 Speaker 1: lack of body fur as in your question here. Of course, 91 00:05:33,120 --> 00:05:36,760 Speaker 1: other behavioral and intellectual things like the capacity for language 92 00:05:36,760 --> 00:05:40,600 Speaker 1: and so forth. But another major difference is that humans 93 00:05:40,640 --> 00:05:45,080 Speaker 1: have way more sweat glands, also known as ekrone glands. 94 00:05:45,560 --> 00:05:48,800 Speaker 1: We have something like ten times the density of ekron 95 00:05:48,880 --> 00:05:53,400 Speaker 1: glands found in animals like chimpanzees and macaques. So we 96 00:05:53,480 --> 00:05:55,760 Speaker 1: are not only the ape that can walk, the ape 97 00:05:55,800 --> 00:05:58,960 Speaker 1: that can talk, We are by far the sweatiest of 98 00:05:59,000 --> 00:06:02,320 Speaker 1: all apes. And so I was looking for some research 99 00:06:02,360 --> 00:06:05,839 Speaker 1: on the genetic basis of this difference in the sweat glands, 100 00:06:06,560 --> 00:06:08,599 Speaker 1: and I found the following study. It was won by 101 00:06:08,680 --> 00:06:13,000 Speaker 1: Daniel aldea at all called repeated mutation of a developmental 102 00:06:13,120 --> 00:06:18,640 Speaker 1: enhancer contributed to human thermoregulatory evolution. This was published in 103 00:06:18,839 --> 00:06:23,480 Speaker 1: Proceedings the National Academy of Sciences in twenty twenty one, 104 00:06:23,720 --> 00:06:26,680 Speaker 1: and it was by a team of researchers I think 105 00:06:26,720 --> 00:06:30,440 Speaker 1: primarily from the University of Pennsylvania School of Medicine, and 106 00:06:30,480 --> 00:06:33,719 Speaker 1: they write in their summary quote, the effectiveness of human 107 00:06:33,800 --> 00:06:38,960 Speaker 1: thermoregulatory sweating is underlain by the evolution of a dramatically 108 00:06:39,120 --> 00:06:44,239 Speaker 1: increased density of water secreting ekrone sweat glands in human 109 00:06:44,320 --> 00:06:48,240 Speaker 1: skin relative to that of other primates. Here we show 110 00:06:48,320 --> 00:06:52,520 Speaker 1: that the accumulation of human specific mutations in a developmental 111 00:06:52,640 --> 00:06:57,560 Speaker 1: enhancer collectively promoted the production of ekrone glands in humans 112 00:06:57,880 --> 00:07:02,520 Speaker 1: by upregulating the expression of the engrailed one also known 113 00:07:02,560 --> 00:07:06,159 Speaker 1: as the e in one transcription factor in the skin. 114 00:07:07,000 --> 00:07:10,239 Speaker 1: So here is apparently the genetic basis of the difference. 115 00:07:10,400 --> 00:07:12,480 Speaker 1: I was reading some comments by the authors in a 116 00:07:12,560 --> 00:07:16,200 Speaker 1: press release associated with this study, and one thing they 117 00:07:16,280 --> 00:07:18,720 Speaker 1: highlighted is that while a lot of other human genetic 118 00:07:18,760 --> 00:07:22,840 Speaker 1: traits that show differences from our nearest relatives are thought 119 00:07:22,880 --> 00:07:26,200 Speaker 1: to come from a complex interaction of different heritable factors. 120 00:07:26,560 --> 00:07:31,280 Speaker 1: The human beings ability to outsweat its relatives seems largely 121 00:07:31,320 --> 00:07:36,280 Speaker 1: traceable to mutations in one single regulatory region called the 122 00:07:36,560 --> 00:07:42,040 Speaker 1: he CE eighteen. Now also related to the study here, Vic, 123 00:07:42,120 --> 00:07:43,800 Speaker 1: We're going to come back to something you asked in 124 00:07:43,880 --> 00:07:47,120 Speaker 1: your email, the part where you wrote, quote, I heard 125 00:07:47,160 --> 00:07:51,040 Speaker 1: something recently that humans actually have the same amount of 126 00:07:51,080 --> 00:07:53,760 Speaker 1: hair on average as a chimpanzee. But human body hair 127 00:07:53,840 --> 00:07:55,880 Speaker 1: is so fine and or short for the most part 128 00:07:56,160 --> 00:07:59,000 Speaker 1: that it doesn't appear to be fur. Well, I was 129 00:07:59,040 --> 00:08:01,800 Speaker 1: reading about the paper I just mentioned in an exerpt 130 00:08:01,840 --> 00:08:04,960 Speaker 1: from a book called The Joy of Sweat, The Strange 131 00:08:04,960 --> 00:08:09,280 Speaker 1: Science of Perspiration by Sarah Everts. This exerpt was published 132 00:08:09,280 --> 00:08:12,160 Speaker 1: by Science Friday, and Everts here cites one of the 133 00:08:12,200 --> 00:08:15,080 Speaker 1: authors of the twenty twenty one study, who is the 134 00:08:15,280 --> 00:08:20,960 Speaker 1: upin Geneticistiana Kambarov, and she confirms that quote we look naked, 135 00:08:21,160 --> 00:08:24,280 Speaker 1: but we are not actually naked. We have the same 136 00:08:24,360 --> 00:08:28,480 Speaker 1: density of hair follicles as apes have fur follicles end 137 00:08:28,480 --> 00:08:32,560 Speaker 1: of quote. But most of those hairs are miniatureized. They're 138 00:08:32,559 --> 00:08:35,560 Speaker 1: shrunken down to the point that they are nearly invisible. 139 00:08:36,160 --> 00:08:39,080 Speaker 1: So yes, it appears vic what you heard was true. 140 00:08:39,120 --> 00:08:42,160 Speaker 1: It's not that we have fewer hair follicles. It's just 141 00:08:42,240 --> 00:08:45,440 Speaker 1: that most of that hair doesn't really it doesn't really 142 00:08:45,480 --> 00:08:49,640 Speaker 1: become you know, it doesn't achieve hair's full potential, so 143 00:08:49,679 --> 00:08:53,200 Speaker 1: we don't have fur coats. Instead, we got little bumps 144 00:08:53,240 --> 00:08:57,720 Speaker 1: and sweat glands and things. So it looks like human 145 00:08:57,760 --> 00:09:01,640 Speaker 1: ancestors underwent multiple changes would have helped keep our bodies 146 00:09:01,720 --> 00:09:05,280 Speaker 1: cooler than would be possible if those bodies were more 147 00:09:05,440 --> 00:09:08,800 Speaker 1: like the bodies of chimpanzees. And those changes are the 148 00:09:08,840 --> 00:09:12,000 Speaker 1: reduction and body fur and the higher density of sweat 149 00:09:12,040 --> 00:09:15,800 Speaker 1: glands for evaporative cooling. Now, another thing that's worth noting 150 00:09:15,880 --> 00:09:19,960 Speaker 1: is that these adaptations stack. The loss of body hair 151 00:09:20,120 --> 00:09:24,720 Speaker 1: appears to make sweating more useful as a cooling technique, 152 00:09:24,800 --> 00:09:27,120 Speaker 1: because if you think about it, it's like harder to 153 00:09:27,160 --> 00:09:30,080 Speaker 1: achieve much evaporative cooling if you are covered in a 154 00:09:30,160 --> 00:09:33,960 Speaker 1: mat of fur. And it also seems that these two 155 00:09:34,040 --> 00:09:37,240 Speaker 1: changes could even have a common cause. Coming back to 156 00:09:37,280 --> 00:09:41,880 Speaker 1: that exerpt from the book by Sarah Everts, she's writing 157 00:09:41,880 --> 00:09:46,240 Speaker 1: about research by Camperov and colleagues. Quote. Camberov and her 158 00:09:46,240 --> 00:09:50,280 Speaker 1: colleagues are finding evidence that the biological signals nudging these 159 00:09:50,280 --> 00:09:55,559 Speaker 1: precursor cells toward an ekrone sweat gland density also inhibit 160 00:09:55,720 --> 00:09:59,439 Speaker 1: the formation of hair. So given all this evidence, it 161 00:09:59,480 --> 00:10:02,480 Speaker 1: seems very plausible to me that there was a pressure 162 00:10:02,520 --> 00:10:06,920 Speaker 1: on our ancestors causing them to survive and reproduce better 163 00:10:07,080 --> 00:10:10,840 Speaker 1: if they could cool their bodies more efficiently. Now, what 164 00:10:10,840 --> 00:10:14,319 Speaker 1: would that pressure be. It could be that they changed habitats, 165 00:10:14,520 --> 00:10:17,720 Speaker 1: maybe say from living in fully shaded forests with like 166 00:10:17,720 --> 00:10:22,160 Speaker 1: a thick canopy cover to living in more direct sunlight, 167 00:10:22,240 --> 00:10:25,000 Speaker 1: either in an open savannah or in a woodland that 168 00:10:25,120 --> 00:10:28,280 Speaker 1: was less dense with thinner canopy and more direct sun. 169 00:10:28,840 --> 00:10:31,560 Speaker 1: Or it could be a change in survival niches, behavioral 170 00:10:31,600 --> 00:10:36,720 Speaker 1: survival niches, So imagine a change to relying on more strenuous, 171 00:10:36,760 --> 00:10:41,520 Speaker 1: prolonged exercise to survive, maybe through endurance running during hunting 172 00:10:41,600 --> 00:10:43,880 Speaker 1: or something else. Or there could be reasons that we're 173 00:10:43,920 --> 00:10:47,360 Speaker 1: not even thinking of that would have caused this need 174 00:10:47,440 --> 00:10:52,640 Speaker 1: to cool the body. So the thermoregulation explanation seems pretty 175 00:10:52,640 --> 00:10:55,959 Speaker 1: strong to me, maybe the probably the strongest explanation I've 176 00:10:55,960 --> 00:10:58,600 Speaker 1: come across, But there are plenty of other possible reasons 177 00:10:58,640 --> 00:11:02,760 Speaker 1: for ancestral fur laws, and they could have been complementary 178 00:11:02,800 --> 00:11:05,520 Speaker 1: to one another. I'm not going to cover all of 179 00:11:05,559 --> 00:11:08,880 Speaker 1: the hypotheses out there, but one other idea we've talked 180 00:11:08,920 --> 00:11:12,760 Speaker 1: about on the show before is the role of ectoparasites. 181 00:11:13,040 --> 00:11:16,080 Speaker 1: And here I'm going to consult a paper called a 182 00:11:16,200 --> 00:11:19,679 Speaker 1: naked ape would have fewer parasites. This was published in 183 00:11:19,720 --> 00:11:23,000 Speaker 1: two thousand and three by Mark Pagel and Walter Bodner 184 00:11:23,360 --> 00:11:26,240 Speaker 1: in Proceedings of the Royal Society of London Series B 185 00:11:26,440 --> 00:11:32,080 Speaker 1: Biological Sciences. From their abstract, they write, quote, Unusually among 186 00:11:32,120 --> 00:11:35,640 Speaker 1: the mammals, humans lack an outer layer of protective fur 187 00:11:35,840 --> 00:11:39,960 Speaker 1: or hair. We propose the hypothesis that humans evolved hairlessness 188 00:11:39,960 --> 00:11:46,000 Speaker 1: to reduce parasite loads, especially ectoparasites that may carry disease. 189 00:11:46,480 --> 00:11:50,200 Speaker 1: We suggest that hairlessness is maintained by these naturally selected 190 00:11:50,240 --> 00:11:55,720 Speaker 1: benefits and bisexual selection operating on both sexes. Hairlessness is 191 00:11:55,760 --> 00:11:58,840 Speaker 1: made possible in humans owing to their unique abilities to 192 00:11:58,880 --> 00:12:04,040 Speaker 1: regulate their environment via fire, shelter, and clothing. So, to 193 00:12:04,160 --> 00:12:08,600 Speaker 1: summarize elements of this hypothesis, you know we can get ticks, 194 00:12:08,720 --> 00:12:12,840 Speaker 1: we can get lice, and these parasites infest body hair, 195 00:12:13,040 --> 00:12:15,880 Speaker 1: they become harder to remove if that hair is thick, 196 00:12:16,280 --> 00:12:19,360 Speaker 1: and they're not just annoying like they spread disease. So 197 00:12:19,400 --> 00:12:22,600 Speaker 1: they do actually have an impact on survival and fitness 198 00:12:22,640 --> 00:12:27,400 Speaker 1: in a natural setting. Once humans could control fire and 199 00:12:27,600 --> 00:12:31,680 Speaker 1: could surround themselves with external insulation, now that might be 200 00:12:31,920 --> 00:12:34,240 Speaker 1: what you would think of his clothing, like maybe animal 201 00:12:34,320 --> 00:12:38,560 Speaker 1: skins or grass or other auxiliary materials from the environment, 202 00:12:38,679 --> 00:12:41,160 Speaker 1: or it could be thinking of shelters. All of these 203 00:12:41,240 --> 00:12:46,440 Speaker 1: changes make it less important to have biological equipment for 204 00:12:46,559 --> 00:12:50,000 Speaker 1: keeping warm, meaning the fur that other mammals have for 205 00:12:50,120 --> 00:12:55,000 Speaker 1: warmth is just less necessary for survival if you've got fire, clothes, shelter. 206 00:12:55,480 --> 00:13:00,000 Speaker 1: It's also possible that if hairlessness enhances survival benefits by 207 00:13:00,040 --> 00:13:05,040 Speaker 1: reducing parasite loads, it could also help enhance reproductive fitness 208 00:13:05,080 --> 00:13:09,319 Speaker 1: through sexual selection by providing an honest signal to potential 209 00:13:09,400 --> 00:13:13,240 Speaker 1: mates of the lack of external parasites. Sort of, you know, 210 00:13:13,800 --> 00:13:16,200 Speaker 1: look and see how attractive I am, And in this case, 211 00:13:16,240 --> 00:13:21,840 Speaker 1: attractive means relatively free of lice and ticks. And there's 212 00:13:21,840 --> 00:13:25,600 Speaker 1: another interesting point of comparison the authors make. They say, 213 00:13:25,679 --> 00:13:28,880 Speaker 1: you know, what are some other mammals that are relatively hairless, well, 214 00:13:28,880 --> 00:13:32,480 Speaker 1: one would be naked mole rats. These are animals that 215 00:13:32,520 --> 00:13:36,560 Speaker 1: live in large colonies underground where you would expect a 216 00:13:36,600 --> 00:13:43,079 Speaker 1: lot of parasite transmission, but their hairlessness offers resistance against ectoparasites. 217 00:13:43,559 --> 00:13:45,760 Speaker 1: And they can of course cope with the lack of 218 00:13:45,800 --> 00:13:48,760 Speaker 1: fur for warmth because they huddle together and they share 219 00:13:48,800 --> 00:13:51,440 Speaker 1: body heat and they stay away from cold air in 220 00:13:51,480 --> 00:13:56,480 Speaker 1: their subterranean layers. So what a naked mole rat has 221 00:13:56,520 --> 00:14:00,600 Speaker 1: in a warmth from underground rat piles? We have in 222 00:14:00,720 --> 00:14:05,800 Speaker 1: technology through fire and clothing, and I guess in evaluating 223 00:14:05,800 --> 00:14:09,439 Speaker 1: this hypothesis, I would have questions about, Like my big 224 00:14:09,520 --> 00:14:12,360 Speaker 1: questions would be like, how do the timelines compare. What 225 00:14:12,559 --> 00:14:17,120 Speaker 1: is the evidence of when our ancestors started undergoing mutations 226 00:14:17,160 --> 00:14:20,360 Speaker 1: to lose their fur, and how would that match up 227 00:14:20,400 --> 00:14:23,920 Speaker 1: against to our best guests at the timeline when we 228 00:14:23,960 --> 00:14:28,160 Speaker 1: started controlling fire or wearing clothes or had other forms 229 00:14:28,200 --> 00:14:33,360 Speaker 1: of external insulation. But anyway, very interesting question. Thank you, vic. 230 00:14:41,960 --> 00:14:45,040 Speaker 1: All Right, this next message is about our episodes on 231 00:14:45,200 --> 00:14:49,480 Speaker 1: heart burial, heart removal and heart burial. It's from Kenneth 232 00:14:49,560 --> 00:14:53,520 Speaker 1: in Glasgow. Kenneth says Hi, Rob and Joe, thanks for 233 00:14:53,560 --> 00:14:56,520 Speaker 1: the fascinating episodes discussing all the ins and outs of 234 00:14:56,600 --> 00:15:00,040 Speaker 1: heart removal. You finally helped me make sense of the 235 00:15:00,080 --> 00:15:04,160 Speaker 1: post mortem journey of the Heart of the Bruce. Robert 236 00:15:04,200 --> 00:15:07,680 Speaker 1: the Bruce was the Scottish king responsible for the defeat 237 00:15:07,720 --> 00:15:12,880 Speaker 1: of the English army at Bannockburn, effectively ending plantagenet claims 238 00:15:12,920 --> 00:15:15,960 Speaker 1: to the Scottish throne. When it came time for him 239 00:15:15,960 --> 00:15:18,600 Speaker 1: to consider his own death, he requested that his heart 240 00:15:18,680 --> 00:15:21,640 Speaker 1: be taken on a tour of the Holy Land. His 241 00:15:21,960 --> 00:15:25,680 Speaker 1: entrails were buried where he died in Cardross, and his 242 00:15:25,800 --> 00:15:29,840 Speaker 1: body went to dunferm Lean Alley. A night by the 243 00:15:29,920 --> 00:15:32,680 Speaker 1: name of Sir James Douglas took the heart in the 244 00:15:32,720 --> 00:15:37,680 Speaker 1: form of a metal urn on a necklace with him. 245 00:15:38,000 --> 00:15:40,400 Speaker 1: I assume this means on one of the Crusades, but 246 00:15:40,480 --> 00:15:44,640 Speaker 1: I'm not sure. But then Kenneth continues, but on the 247 00:15:44,680 --> 00:15:47,880 Speaker 1: way he was called to help fight the Moors in Spain. 248 00:15:48,520 --> 00:15:52,360 Speaker 1: At some point during the Battle of Taba, Douglas is 249 00:15:52,360 --> 00:15:54,680 Speaker 1: said to have hurled the heart into the midst of 250 00:15:54,720 --> 00:15:58,640 Speaker 1: the enemy with the cry, lead on, braveheart, I'll follow 251 00:15:58,680 --> 00:16:02,840 Speaker 1: the entheses. No prizes for guessing where the movie got 252 00:16:02,880 --> 00:16:08,080 Speaker 1: its title. Douglas, killed in battle, was then transported back 253 00:16:08,120 --> 00:16:11,880 Speaker 1: to Scotland with the heart and buried near Melrose Abbey. 254 00:16:11,960 --> 00:16:15,440 Speaker 1: The heart itself was exhumed and reburied within the abbey 255 00:16:15,480 --> 00:16:18,800 Speaker 1: in nineteen ninety six. I had no idea heart burial 256 00:16:18,880 --> 00:16:21,440 Speaker 1: had been such a widespread tradition, so the story of 257 00:16:21,520 --> 00:16:24,760 Speaker 1: Robert the Bruce's heart had always seemed very strange. Thank 258 00:16:24,800 --> 00:16:28,920 Speaker 1: you for giving it context. Kenneth from Glasgow. Thank you, Kenneth. 259 00:16:29,160 --> 00:16:32,440 Speaker 1: Very interesting all right. This next message is in response 260 00:16:32,480 --> 00:16:42,360 Speaker 1: to our episodes on tea. This is from Eric. Eric says, hey, 261 00:16:42,440 --> 00:16:45,080 Speaker 1: Rob and Joe. I enjoyed your episodes about tea and 262 00:16:45,240 --> 00:16:48,160 Speaker 1: its accessories. One thing that could have been mentioned is 263 00:16:48,200 --> 00:16:52,120 Speaker 1: the Utah teapot, which is an object commonly rendered when 264 00:16:52,160 --> 00:16:56,240 Speaker 1: testing computer graphics. I remember seeing teapots everywhere in my 265 00:16:56,280 --> 00:16:59,120 Speaker 1: early computer science courses, and it's pretty common to see 266 00:16:59,120 --> 00:17:03,040 Speaker 1: a teapot hid or not so hidden in various video 267 00:17:03,080 --> 00:17:08,359 Speaker 1: games or rendering engines like CAD software that's computer aided 268 00:17:08,400 --> 00:17:11,199 Speaker 1: design or something CAD software. You can look up what 269 00:17:11,200 --> 00:17:13,879 Speaker 1: it stands for. It's sort of an in joke for 270 00:17:14,040 --> 00:17:17,520 Speaker 1: computer nerds. I always thought that a teapot was an 271 00:17:17,520 --> 00:17:20,760 Speaker 1: odd choice since everyone knows that software is ultimately fueled 272 00:17:20,800 --> 00:17:24,439 Speaker 1: by coffee. But it makes sense since the teapot is 273 00:17:24,480 --> 00:17:28,040 Speaker 1: a really unique and non uniform object, so it's more 274 00:17:28,080 --> 00:17:32,080 Speaker 1: complicated than a simple sphere or polyhedron. But it's also 275 00:17:32,240 --> 00:17:35,080 Speaker 1: smooth and shiny, which is a lot easier to render 276 00:17:35,119 --> 00:17:38,359 Speaker 1: than something with rough or fuzzy textures. Thanks for the 277 00:17:38,359 --> 00:17:42,960 Speaker 1: great episodes, Eric, Okay. One last message this comes from Kurt. 278 00:17:48,280 --> 00:17:51,600 Speaker 1: Kurt says, hey guys, longtime listener over the years. I 279 00:17:51,640 --> 00:17:53,600 Speaker 1: don't know why this just occurred to me today. I 280 00:17:53,640 --> 00:17:56,520 Speaker 1: was listening to the three part series on tea recently. 281 00:17:57,119 --> 00:17:59,560 Speaker 1: In the third part, Joe started to talk about the 282 00:17:59,680 --> 00:18:04,520 Speaker 1: drip tea spout problem and Russell's teapot analogy. This started 283 00:18:04,560 --> 00:18:07,359 Speaker 1: to take the conversation outside the realm of the subject, 284 00:18:07,440 --> 00:18:10,360 Speaker 1: with just a thread of the original topic. This isn't 285 00:18:10,359 --> 00:18:12,960 Speaker 1: a criticism at all. I like the tangents that bring 286 00:18:13,080 --> 00:18:15,760 Speaker 1: up the things that I probably wouldn't otherwise think about 287 00:18:15,840 --> 00:18:19,240 Speaker 1: in that moment. My question is what is your process 288 00:18:19,280 --> 00:18:22,000 Speaker 1: for creating episodes based on a topic. Do you have 289 00:18:22,040 --> 00:18:25,359 Speaker 1: discussions beforehand about areas you'd like to investigate, or do 290 00:18:25,400 --> 00:18:29,360 Speaker 1: you both investigate certain areas individually and just see where 291 00:18:29,400 --> 00:18:32,040 Speaker 1: it takes you without the other person knowing what topics 292 00:18:32,040 --> 00:18:34,520 Speaker 1: you'll bring up. If so, is it more of a 293 00:18:34,560 --> 00:18:37,920 Speaker 1: surprise where the conversations take you based on this, as 294 00:18:38,040 --> 00:18:40,760 Speaker 1: neither of you would have a full indication as to 295 00:18:40,760 --> 00:18:43,480 Speaker 1: where a conversation might go. I don't know if you've 296 00:18:43,480 --> 00:18:45,680 Speaker 1: outlined this before. You guys have a ton of episodes 297 00:18:45,680 --> 00:18:49,960 Speaker 1: and mail ins, so it might have been addressed previously. Anyway, 298 00:18:49,960 --> 00:18:52,960 Speaker 1: Thanks for what you guys are doing. Love being in 299 00:18:53,200 --> 00:18:57,720 Speaker 1: on the conversations no matter where they go. Kurt, Well, Kurt, 300 00:18:57,800 --> 00:19:02,240 Speaker 1: thank you for the message. Yeah, I guess our method 301 00:19:02,520 --> 00:19:05,639 Speaker 1: is somewhat free form, but I'll try to explain as 302 00:19:05,640 --> 00:19:08,800 Speaker 1: best I can. We don't approach every episode exactly the 303 00:19:08,840 --> 00:19:11,720 Speaker 1: same way, but most of the time it looks something 304 00:19:11,760 --> 00:19:13,800 Speaker 1: like this. You know, one of us gets an idea 305 00:19:13,960 --> 00:19:17,280 Speaker 1: and shares it with the other and we will talk 306 00:19:17,320 --> 00:19:19,480 Speaker 1: it over and figure out if it will actually make 307 00:19:19,520 --> 00:19:23,400 Speaker 1: for a good episode. So after we do that, after 308 00:19:23,400 --> 00:19:26,400 Speaker 1: we figure out that something is probably a solid episode 309 00:19:26,440 --> 00:19:28,960 Speaker 1: or has a series in it, we you know, work 310 00:19:29,080 --> 00:19:33,560 Speaker 1: from a shared notes document which contains some pre written 311 00:19:33,600 --> 00:19:36,119 Speaker 1: thoughts and information that we want to refer back to. 312 00:19:36,320 --> 00:19:38,480 Speaker 1: But it's not like a strict script. So what you 313 00:19:38,600 --> 00:19:41,840 Speaker 1: hear in an episode is a mix of some pre 314 00:19:41,920 --> 00:19:46,640 Speaker 1: written thoughts, some paraphrasing and summarizing of notes, some extemporaneous 315 00:19:46,680 --> 00:19:50,199 Speaker 1: thoughts and conversation. And ultimately this means that we know 316 00:19:50,359 --> 00:19:53,240 Speaker 1: some things, but not everything that's going to happen going 317 00:19:53,320 --> 00:19:56,320 Speaker 1: in and so are there are still often plenty of 318 00:19:56,359 --> 00:19:59,240 Speaker 1: surprises we have for ourselves and for each other during 319 00:19:59,240 --> 00:20:03,240 Speaker 1: a recording session, and sometimes we do agree beforehand on 320 00:20:03,280 --> 00:20:08,040 Speaker 1: which subtopics we'll focus on, but sometimes not often. I've 321 00:20:08,080 --> 00:20:10,040 Speaker 1: said this on the show before, but the you know, 322 00:20:10,320 --> 00:20:13,280 Speaker 1: the contents of the episode are kind of an emergent 323 00:20:14,000 --> 00:20:17,159 Speaker 1: result of the research process. It's not like we can 324 00:20:17,680 --> 00:20:21,520 Speaker 1: know before researching what all of the interesting things to 325 00:20:21,520 --> 00:20:23,640 Speaker 1: talk about will be. It's kind of through the process 326 00:20:23,640 --> 00:20:28,400 Speaker 1: of reading about something that we discover even what questions 327 00:20:28,440 --> 00:20:31,680 Speaker 1: there are to look into. So so, yeah, a lot 328 00:20:31,720 --> 00:20:33,720 Speaker 1: of times we just kind of end up going on 329 00:20:33,760 --> 00:20:36,520 Speaker 1: our own tangents and then we have something interesting to 330 00:20:36,520 --> 00:20:40,120 Speaker 1: come share with each other when we return. But other times, yeah, 331 00:20:40,119 --> 00:20:42,040 Speaker 1: we know about certain things we're going to look into, 332 00:20:42,080 --> 00:20:45,600 Speaker 1: and we we kind of divvy it up accordingly. So 333 00:20:45,640 --> 00:20:47,960 Speaker 1: to answer your question as directly as I can, it's 334 00:20:48,000 --> 00:20:50,720 Speaker 1: just it's a mixed bags. Our conversations on Mike are 335 00:20:51,240 --> 00:20:54,880 Speaker 1: partly predictable to each other and partly surprising to each other. 336 00:20:55,600 --> 00:20:57,520 Speaker 1: All right, I think that's going to do it for 337 00:20:57,760 --> 00:21:03,199 Speaker 1: the mail bag today. One more reminder. We're going to 338 00:21:03,240 --> 00:21:06,760 Speaker 1: be running a vault episode tomorrow, and then we'll be 339 00:21:06,800 --> 00:21:10,400 Speaker 1: back with new episodes for you on Wednesday, and going 340 00:21:10,440 --> 00:21:12,560 Speaker 1: forward after that, we should have a new Core episode 341 00:21:12,600 --> 00:21:15,680 Speaker 1: for you on Thursday of this week. If you're new here, 342 00:21:16,000 --> 00:21:18,680 Speaker 1: this is the Stuff to Blow your Mind podcast. Our 343 00:21:18,680 --> 00:21:22,520 Speaker 1: Core episodes publish every Tuesday and Thursday. Those are most 344 00:21:22,560 --> 00:21:25,800 Speaker 1: often about science, but we also hop across disciplines and 345 00:21:26,000 --> 00:21:28,880 Speaker 1: get into all sorts of things. On Mondays, we read 346 00:21:28,920 --> 00:21:32,040 Speaker 1: back listener mail in episodes like this one, though usually 347 00:21:32,280 --> 00:21:37,000 Speaker 1: both Robert and I are co hosting them. On Wednesdays, 348 00:21:37,200 --> 00:21:41,000 Speaker 1: we do a short form episode called The Artifact or 349 00:21:41,040 --> 00:21:44,120 Speaker 1: the Monster Fact. On Fridays. When the week is done, 350 00:21:44,640 --> 00:21:47,000 Speaker 1: it's time for Weird House Cinema. That's a series we 351 00:21:47,040 --> 00:21:49,680 Speaker 1: do where Rob and I just to feature and discuss 352 00:21:49,720 --> 00:21:54,120 Speaker 1: a weird movie. Weird is really the only criterion. Sometimes 353 00:21:54,119 --> 00:21:57,000 Speaker 1: we look at great movies, sometimes we look at bad movies. 354 00:21:57,200 --> 00:22:01,360 Speaker 1: Some are well known classics, are obscure that nobody's ever 355 00:22:01,400 --> 00:22:04,080 Speaker 1: heard about. Basically all of its fair game as long 356 00:22:04,119 --> 00:22:07,480 Speaker 1: as it's weird. And then, finally, on Saturday's we feature 357 00:22:07,640 --> 00:22:11,880 Speaker 1: an episode from The Fault So Big thanks to our 358 00:22:11,960 --> 00:22:15,200 Speaker 1: audio producer JJ Pauseway. If you would like to get 359 00:22:15,240 --> 00:22:17,840 Speaker 1: in touch with us with feedback on this episode or 360 00:22:17,840 --> 00:22:21,240 Speaker 1: any other, to share your thoughts, or to share something 361 00:22:21,840 --> 00:22:25,080 Speaker 1: that you think we'd be interested in, to suggest a 362 00:22:25,160 --> 00:22:27,560 Speaker 1: topic for the future, or just to say hello, you 363 00:22:27,560 --> 00:22:30,600 Speaker 1: can email us at contact at stuff to blow your 364 00:22:30,600 --> 00:22:39,720 Speaker 1: Mind dot com. Stuff to Blow Your Mind is a 365 00:22:39,720 --> 00:22:42,920 Speaker 1: production of iHeartRadio. For more podcasts from my heart Radio, 366 00:22:43,160 --> 00:22:46,240 Speaker 1: visit the iHeartRadio app, Apple Podcasts, or wherever you listen 367 00:22:46,320 --> 00:22:47,240 Speaker 1: to your favorite shows.