WEBVTT - Are Humans Still Evolving? 0:00:00.240 --> 0:00:02.320 A brain Stuff listeners. If you're like me, I bet 0:00:02.400 --> 0:00:04.600 you love to learn new things, and that's why I 0:00:04.640 --> 0:00:07.760 want to tell you about the Great Courses Plus. It's 0:00:07.760 --> 0:00:11.640 a video learning service that provides unlimited access to a 0:00:11.760 --> 0:00:15.840 huge library of lecture series that are about totally fascinating 0:00:15.880 --> 0:00:19.200 subjects like science, history, cooking, you name it. I think 0:00:19.200 --> 0:00:21.400 that you should try it out. The Great Courses Plus 0:00:21.600 --> 0:00:23.880 wants you to try it out, So we're going to 0:00:23.920 --> 0:00:27.320 give you brain stuff listeners a special chance to watch 0:00:27.360 --> 0:00:31.479 their popular course The Inexplicable Universe, Unsolved Mysteries, and hundreds 0:00:31.480 --> 0:00:35.000 of other courses totally free. And get this. 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I hope you survived the experience. 0:01:19.800 --> 0:01:22.479 I'm Christian Sager, and I'm the best there is at 0:01:22.520 --> 0:01:25.080 what I do. And today I'm going to tell you 0:01:25.160 --> 0:01:29.679 how human beings are still evolving. But into what I mean, like, 0:01:29.720 --> 0:01:33.240 where are cool mutant powers that cause fear and hate 0:01:33.280 --> 0:01:36.600 in those were sworn to protect? Where's my organic steel 0:01:36.640 --> 0:01:40.640 skin or my optic I beams? Well, contrary to some 0:01:40.760 --> 0:01:46.880 professor's assertions, evolution does not leap forward. Most experts agree 0:01:47.080 --> 0:01:50.080 that to give rise to a new species like mutants, 0:01:50.440 --> 0:01:55.200 we need some kind of geographic isolation from other humans. Otherwise, 0:01:55.560 --> 0:01:58.920 cross breeding makes it less likely that mutations will be 0:01:59.000 --> 0:02:02.720 established in our gene pool, and with a densely packed 0:02:02.760 --> 0:02:07.360 planet full of planes and cars, it's highly unlikely we're 0:02:07.360 --> 0:02:10.520 going to find that kind of seclusion. Think of it 0:02:10.560 --> 0:02:14.000 this way. Genetic mutations are only passed down if they 0:02:14.040 --> 0:02:17.600 afford us some kind of benefit through natural selection. That 0:02:17.680 --> 0:02:21.079 doesn't mean we've stopped evolving. In fact, over time, we've 0:02:21.120 --> 0:02:25.519 already developed powers well sort of like how about the 0:02:25.560 --> 0:02:30.320 power to drink milk or fight disease because these, along 0:02:30.360 --> 0:02:33.520 with tiny teeth and small brains, are the mutant powers 0:02:33.560 --> 0:02:36.200 most of us are born with. Let's start with the 0:02:36.200 --> 0:02:41.520 milk powers, otherwise known as lactase persistence see. Milk contains 0:02:41.520 --> 0:02:44.880 a sugar called lactose, and people need an enzyme called 0:02:44.960 --> 0:02:49.240 lactase to digest it. Most mammals lose this enzyme after 0:02:49.280 --> 0:02:53.880 they stop breastfeeding, but certain human populations have evolved so 0:02:53.960 --> 0:02:58.560 their lactase persists, allowing the digestion of milk. This was 0:02:58.680 --> 0:03:03.639 nutritionally advantage, just especially when we domesticated cows and goats. 0:03:04.120 --> 0:03:08.240 Now this genetic mutation is carried by more than of 0:03:08.320 --> 0:03:13.720 people of Northern European descent. Researchers have also found signs 0:03:13.800 --> 0:03:16.680 of another set of human mutations that were devoted to 0:03:16.760 --> 0:03:22.480 fighting off infectious diseases. Afflictions like malaria or tuberculosis. Used 0:03:22.480 --> 0:03:25.680 to mean bang, you're dead, But over the last forty 0:03:25.760 --> 0:03:29.680 thousand years we evolve to be more resistant to disease 0:03:30.120 --> 0:03:33.080 because our ancestors happen to have the right genes to 0:03:33.200 --> 0:03:37.240 fight off these viruses and bacteria. Our mutant power to 0:03:37.320 --> 0:03:40.720 resist disease may not last much longer, however, as we 0:03:40.840 --> 0:03:44.920 become more dependent on medications for survival, our immune systems 0:03:44.960 --> 0:03:49.000 will slowly weaken. The more that pathogens are defeated by drugs, 0:03:49.040 --> 0:03:51.800 the less our body will need the internal functions to 0:03:51.880 --> 0:03:55.160 withstand them. This is not to say that modern medicine 0:03:55.200 --> 0:03:58.640 or vaccinations are bad, because without them we'd see a 0:03:58.760 --> 0:04:02.520 huge increase in zas related death, which I'm going to 0:04:02.560 --> 0:04:06.040 assume you also think is a bad thing. So maybe 0:04:06.080 --> 0:04:08.840 milk powers or anti disease genes aren't what you were 0:04:08.880 --> 0:04:13.360 hoping for. What about smaller jaws and less teeth. Our 0:04:13.400 --> 0:04:16.640 ancestors had huge jaws so they could chew on tough 0:04:16.680 --> 0:04:20.200 foods like roots and nuts, and wisdom teeth helped them 0:04:20.240 --> 0:04:23.800 replace their worn down pearly whites from tearing meat apart 0:04:24.080 --> 0:04:27.839 with no quarter asked and none given. But today our 0:04:27.839 --> 0:04:31.520 food is softer, easier to chew, and we use utensils 0:04:31.560 --> 0:04:35.080 to cut the portions we put into our mouths. Consequently, 0:04:35.120 --> 0:04:38.080 our jaws got smaller, our teeth are half the size 0:04:38.120 --> 0:04:40.599 they used to be, and we don't really need wisdom 0:04:40.640 --> 0:04:44.160 teeth anymore. They're already gone in some ethnic groups, and 0:04:44.279 --> 0:04:49.200 many predict they'll disappear entirely now I don't need telepathy 0:04:49.240 --> 0:04:52.000 to know that you think these are really lame powers. 0:04:52.000 --> 0:04:55.200 How about one more mutation. Did you know that our 0:04:55.240 --> 0:04:58.799 brains have been shrinking for the last thirty thousand years. 0:04:58.839 --> 0:05:02.440 Some researchers think this means we're getting dumber, because the 0:05:02.520 --> 0:05:07.240 safety of modern society doesn't require intelligence for survival, but 0:05:07.360 --> 0:05:11.000 others argue that smaller brains just mean they're more efficient. 0:05:11.360 --> 0:05:14.560 Maybe our wiring up there takes up less room because 0:05:14.600 --> 0:05:17.839 it's faster, like when you get a newer, smaller phone 0:05:18.200 --> 0:05:21.440 that has better RAM than your old one. Hopefully, as 0:05:21.520 --> 0:05:24.839 my brain reaches peak efficiency, I'll be able to focus 0:05:24.920 --> 0:05:27.720 the totality of my psyche into some kind of weapon. 0:05:32.920 --> 0:05:34.919 Check out the brain stuff channel on YouTube, and for 0:05:35.000 --> 0:05:37.440 more on this and thousands of other topics, visit how 0:05:37.480 --> 0:05:51.920 stuff works dot com.