1 00:00:00,240 --> 00:00:02,320 Speaker 1: A brain Stuff listeners. If you're like me, I bet 2 00:00:02,400 --> 00:00:04,600 Speaker 1: you love to learn new things, and that's why I 3 00:00:04,640 --> 00:00:07,760 Speaker 1: want to tell you about the Great Courses Plus. It's 4 00:00:07,760 --> 00:00:11,640 Speaker 1: a video learning service that provides unlimited access to a 5 00:00:11,760 --> 00:00:15,840 Speaker 1: huge library of lecture series that are about totally fascinating 6 00:00:15,880 --> 00:00:19,200 Speaker 1: subjects like science, history, cooking, you name it. I think 7 00:00:19,200 --> 00:00:21,400 Speaker 1: that you should try it out. 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And now 15 00:00:44,960 --> 00:00:47,680 Speaker 1: the Great Courses Plus is offering brain Stuff listeners a 16 00:00:47,760 --> 00:00:50,920 Speaker 1: chance to stream hundreds of their courses, including that Neil 17 00:00:50,960 --> 00:00:55,920 Speaker 1: de grass Tyson series, which is dollars of value totally free. 18 00:00:56,160 --> 00:00:57,720 Speaker 1: All you have to do is go to the Great 19 00:00:57,720 --> 00:01:01,520 Speaker 1: Courses Plus dot com slash brain Stuff and it's yours 20 00:01:01,560 --> 00:01:04,759 Speaker 1: for free. That is the Great Courses plus dot com 21 00:01:04,800 --> 00:01:10,639 Speaker 1: slash brain Stuff. Welcome to brain Stuff from how Stuff Works. 22 00:01:16,560 --> 00:01:19,600 Speaker 1: Welcome to brain Stuff. I hope you survived the experience. 23 00:01:19,800 --> 00:01:22,479 Speaker 1: I'm Christian Sager, and I'm the best there is at 24 00:01:22,520 --> 00:01:25,080 Speaker 1: what I do. And today I'm going to tell you 25 00:01:25,160 --> 00:01:29,679 Speaker 1: how human beings are still evolving. But into what I mean, like, 26 00:01:29,720 --> 00:01:33,240 Speaker 1: where are cool mutant powers that cause fear and hate 27 00:01:33,280 --> 00:01:36,600 Speaker 1: in those were sworn to protect? Where's my organic steel 28 00:01:36,640 --> 00:01:40,640 Speaker 1: skin or my optic I beams? Well, contrary to some 29 00:01:40,760 --> 00:01:46,880 Speaker 1: professor's assertions, evolution does not leap forward. Most experts agree 30 00:01:47,080 --> 00:01:50,080 Speaker 1: that to give rise to a new species like mutants, 31 00:01:50,440 --> 00:01:55,200 Speaker 1: we need some kind of geographic isolation from other humans. Otherwise, 32 00:01:55,560 --> 00:01:58,920 Speaker 1: cross breeding makes it less likely that mutations will be 33 00:01:59,000 --> 00:02:02,720 Speaker 1: established in our gene pool, and with a densely packed 34 00:02:02,760 --> 00:02:07,360 Speaker 1: planet full of planes and cars, it's highly unlikely we're 35 00:02:07,360 --> 00:02:10,520 Speaker 1: going to find that kind of seclusion. Think of it 36 00:02:10,560 --> 00:02:14,000 Speaker 1: this way. Genetic mutations are only passed down if they 37 00:02:14,040 --> 00:02:17,600 Speaker 1: afford us some kind of benefit through natural selection. That 38 00:02:17,680 --> 00:02:21,079 Speaker 1: doesn't mean we've stopped evolving. In fact, over time, we've 39 00:02:21,120 --> 00:02:25,519 Speaker 1: already developed powers well sort of like how about the 40 00:02:25,560 --> 00:02:30,320 Speaker 1: power to drink milk or fight disease because these, along 41 00:02:30,360 --> 00:02:33,520 Speaker 1: with tiny teeth and small brains, are the mutant powers 42 00:02:33,560 --> 00:02:36,200 Speaker 1: most of us are born with. Let's start with the 43 00:02:36,200 --> 00:02:41,520 Speaker 1: milk powers, otherwise known as lactase persistence see. Milk contains 44 00:02:41,520 --> 00:02:44,880 Speaker 1: a sugar called lactose, and people need an enzyme called 45 00:02:44,960 --> 00:02:49,240 Speaker 1: lactase to digest it. Most mammals lose this enzyme after 46 00:02:49,280 --> 00:02:53,880 Speaker 1: they stop breastfeeding, but certain human populations have evolved so 47 00:02:53,960 --> 00:02:58,560 Speaker 1: their lactase persists, allowing the digestion of milk. This was 48 00:02:58,680 --> 00:03:03,639 Speaker 1: nutritionally advantage, just especially when we domesticated cows and goats. 49 00:03:04,120 --> 00:03:08,240 Speaker 1: Now this genetic mutation is carried by more than of 50 00:03:08,320 --> 00:03:13,720 Speaker 1: people of Northern European descent. Researchers have also found signs 51 00:03:13,800 --> 00:03:16,680 Speaker 1: of another set of human mutations that were devoted to 52 00:03:16,760 --> 00:03:22,480 Speaker 1: fighting off infectious diseases. Afflictions like malaria or tuberculosis. Used 53 00:03:22,480 --> 00:03:25,680 Speaker 1: to mean bang, you're dead, But over the last forty 54 00:03:25,760 --> 00:03:29,680 Speaker 1: thousand years we evolve to be more resistant to disease 55 00:03:30,120 --> 00:03:33,080 Speaker 1: because our ancestors happen to have the right genes to 56 00:03:33,200 --> 00:03:37,240 Speaker 1: fight off these viruses and bacteria. Our mutant power to 57 00:03:37,320 --> 00:03:40,720 Speaker 1: resist disease may not last much longer, however, as we 58 00:03:40,840 --> 00:03:44,920 Speaker 1: become more dependent on medications for survival, our immune systems 59 00:03:44,960 --> 00:03:49,000 Speaker 1: will slowly weaken. The more that pathogens are defeated by drugs, 60 00:03:49,040 --> 00:03:51,800 Speaker 1: the less our body will need the internal functions to 61 00:03:51,880 --> 00:03:55,160 Speaker 1: withstand them. This is not to say that modern medicine 62 00:03:55,200 --> 00:03:58,640 Speaker 1: or vaccinations are bad, because without them we'd see a 63 00:03:58,760 --> 00:04:02,520 Speaker 1: huge increase in zas related death, which I'm going to 64 00:04:02,560 --> 00:04:06,040 Speaker 1: assume you also think is a bad thing. So maybe 65 00:04:06,080 --> 00:04:08,840 Speaker 1: milk powers or anti disease genes aren't what you were 66 00:04:08,880 --> 00:04:13,360 Speaker 1: hoping for. What about smaller jaws and less teeth. Our 67 00:04:13,400 --> 00:04:16,640 Speaker 1: ancestors had huge jaws so they could chew on tough 68 00:04:16,680 --> 00:04:20,200 Speaker 1: foods like roots and nuts, and wisdom teeth helped them 69 00:04:20,240 --> 00:04:23,800 Speaker 1: replace their worn down pearly whites from tearing meat apart 70 00:04:24,080 --> 00:04:27,839 Speaker 1: with no quarter asked and none given. But today our 71 00:04:27,839 --> 00:04:31,520 Speaker 1: food is softer, easier to chew, and we use utensils 72 00:04:31,560 --> 00:04:35,080 Speaker 1: to cut the portions we put into our mouths. Consequently, 73 00:04:35,120 --> 00:04:38,080 Speaker 1: our jaws got smaller, our teeth are half the size 74 00:04:38,120 --> 00:04:40,599 Speaker 1: they used to be, and we don't really need wisdom 75 00:04:40,640 --> 00:04:44,160 Speaker 1: teeth anymore. They're already gone in some ethnic groups, and 76 00:04:44,279 --> 00:04:49,200 Speaker 1: many predict they'll disappear entirely now I don't need telepathy 77 00:04:49,240 --> 00:04:52,000 Speaker 1: to know that you think these are really lame powers. 78 00:04:52,000 --> 00:04:55,200 Speaker 1: How about one more mutation. Did you know that our 79 00:04:55,240 --> 00:04:58,799 Speaker 1: brains have been shrinking for the last thirty thousand years. 80 00:04:58,839 --> 00:05:02,440 Speaker 1: Some researchers think this means we're getting dumber, because the 81 00:05:02,520 --> 00:05:07,240 Speaker 1: safety of modern society doesn't require intelligence for survival, but 82 00:05:07,360 --> 00:05:11,000 Speaker 1: others argue that smaller brains just mean they're more efficient. 83 00:05:11,360 --> 00:05:14,560 Speaker 1: Maybe our wiring up there takes up less room because 84 00:05:14,600 --> 00:05:17,839 Speaker 1: it's faster, like when you get a newer, smaller phone 85 00:05:18,200 --> 00:05:21,440 Speaker 1: that has better RAM than your old one. Hopefully, as 86 00:05:21,520 --> 00:05:24,839 Speaker 1: my brain reaches peak efficiency, I'll be able to focus 87 00:05:24,920 --> 00:05:27,720 Speaker 1: the totality of my psyche into some kind of weapon. 88 00:05:32,920 --> 00:05:34,919 Speaker 1: Check out the brain stuff channel on YouTube, and for 89 00:05:35,000 --> 00:05:37,440 Speaker 1: more on this and thousands of other topics, visit how 90 00:05:37,480 --> 00:05:51,920 Speaker 1: stuff works dot com.