Hey there internet, I'm Trace Dominguez for TestTube Plus. This week we're talking about humans, and everything that I could muster about them. We take big topics on this show and we break them down into smaller topics. So, if you never watched before make sure you go back and watch the two episodes we've done so far this week. Of course you can also just watch this one if it's the one you're interested in. Make sure you subscribe for more videos. This week, today, we're talking about how humans got to where we're now. But... I think it's messed up. We keep changing. Our human story keeps changing because we humans keep changing. Evolution kinda forces adaptation. So 1.9 million years ago the genus homo was all over Africa and Asia. The modern humans started to move out of Africa, specifically East Africa where they started as really tiny little squirrel things all way up to the point you see now which you can watch in an early episode. Modern humans moved out of Africa into Arabia about 125,000 years ago. We know this because anthropologists have found stone hand axes. They found scrapers. They found what's called a perforator. They did all of that and they found it in the UAE (United Arabe Emirates). Previously was thought the we move out of Africa about 60,000 years ago. So 125,000 years, that's a huge jump. And what happened is... we found these tools. And that's how hard it is to really determine the history of humanity. It's not like there was a big drone flying and filming all of these people. You know, there was no camera crew. This is all being found by stuff buried under the ground. We have to dig in the right place. We have to dig at the right time of year. We have to be able to get to it and save it. So that we can study it and figure out what it is. Not easy! After that we moved into Europe, about 46,000 years ago, that's why we met the Neanderthals. And of course - like humans do - we bred with them. We mixed our genes. We also found new climates in Europe. Africa's a very different climate than Europe. Europe is a little colder, the weather is a lot different. And because of that we had to adapt. We started learning to make more clothing. We started learning to make tools that could hunt different animals that we had found in Africa. Europe is more mountainous as well, so we had to learn how to get over and around these giant mountains. And unlike Africa, which in parts can be desert, can be grassland Europe doesn't really have a lot of that. So we had to learn new ways to find our food and not a lot of animals can do that. Humans are really good at picking out new ways to do things. Modern humans, like us, probably learned to deal with these changes using tools, domesticating animals, and changing how they lived their whole lives. Which is pretty incredible. We went from being nomatic to hunter-gatherer. We went from being hunter-gatherer to farmers. And this was all over tens of thousands of years. We moved to Asia between 46,000 and 63,000 years ago. We know this because literally we found 1 skull in a cave in Laos. The skull was not actually put in that cave by a human.
It wouldn't've died there. They actually think that it was washed into that cave via a rainy season monsoon perhaps. But they found it there and they used what they knew about that cave, and about that region, and about that skull,
to determine that humans had migrated there at some point. Again, 46,000 to 63,000 years ago. So the story keeps getting updated every time we find something. North and South America were populated by humans when a land bridge existed across the Bering Strait between Northeast Russia and Alaska. But unlike what you may be picturing right now, which is really like a skinny little bridge, they do think that the land bridge was really huge,
like it was hundreds of miles across. And people moved onto the land bridge from Northern China - what would be Northern China,
Mongolia and Russia and into this land bridge area.
They lived there for a while and then eventually (13,000 years ago) they were forced off the land bridge as the water started to rise and they moved into the United States. This means that unlike some theories that Native Americans were essentially just Asians that had walked across the land bridge and set up camp over in Canada, there was instead a cousin of the Asian human because they'd bred for so long on the land bridge. It was actually a whole separated group and over time things changed. Here's an example of how things changed: Cow's milk. We domesticated cows 10,500 years ago probably in Iran or what would be considered Iran today or the Persian Empire area. They've determined actually there was 80 original female cows That all domesticated cows descend from. Who were very difficult to domesticate, actually. According to people's research. And it turns out some people couldn't drink cow's milk. We can drink human milk for a very short amount of time and then our genes turn off the ability for us to drink milk. Usually. Some people on the other hand have a gene mutation where the gene never turns off. And since mothers don't make milk our whole lives we supplemented that, because is very nutritious, with cow's milk. This didn't extend to everywhere in the world but only certain groups of humans who got this genetic adaptation. For example: In Southern Sudan 17% of people cannot drink milk. Most of them can, but the people of the Southern Sudan were cattle farmers. So chances are they adapted. That is to say people that couldn't drink milk didn't get as much nutrition and couldn't compete with the people that could drink milk. The ones that could adapted and were able to survive. The ones that couldn't, died. Native Americans didn't have domesticated cow. They would drink milk as babies and then they didn't. So Native Americans 100% cannot process lactose. 99% of the Ebo (Igbo) in Yoruba tribes, in Nigeria, cannot digest milk. 90% of people who originated from Japan and Thailand cannot process milk. Whereas in Sweden only 4% of people can't process milk. So I guess you can tell who was drinking milk just by looking at lactose intolarence. Who was doing well by drinking this milk. In Switzerland, Spain and Finland it's about 20% of people who are lactose intolerant. And to combat this in some parts of the world they started learning to make cheese because cheese actually has a different or a lower level of the protein or the enzyme lactose. So 11,000 years ago people coped with that increase in lactose in cow's milk by learning to make cheese. They found anthropological evidence - cheese strainers. Very funny. Actually, you should look those up. They're pretty cool. You can find them on discoverynews.com The genes eventually didn't shut off and now we are left with their legacy. Where some of us are lactose intolerant and other are not. These nutrition changes allowed people to adapt and live in other places. And it wasn't just milk. For example the Inuit people, who live far north in North America, they may be able to digest fats better than, say, people from Western Europe. Native Americans may not be able to drink milk that well but the Native Americans of Arizona could eat corn, beans and squash as an entirety of their diet and still have very slender bodies but Western Europeans can't. So it really dependant on where you lived and as the time went by things changed. We needed more or less height depending on what we could compete with. We needed lots of different foods. Some tribes around the world, some small human groups, didn't eat a lot of varied food. Some ate very specific foods. So people who couldn't eat the things that needed to eat... died. Because that's how evolution works. That's how adaptation works. Think of those in Southern Sudan with the cattle farming. They'd also learned to hunt different animals. Some theorize, like Christopher McDougall in his book "Born to Run" he also has a TED talk about that from the pen TEDx, I think. He believes, and other researchers as well, that humans, we don't have claws or sharp teeth, but we can run really well. We can run for a long time because we're good sweaters, we run fast but not too fast and we can run for a long, long time. Think marathon runners. How many other animals run for 20 miles or more straight? Very few, if any. Tools plus running, that makes us good hunters. So maybe that's how those people, and maybe all people, adapted to their surroundings. But honestly again, there are no camera crews. There are no storytellers. We don't really know. Some different skin tones also started to come about as an adaptation to certain humans. A study in Nature found the about 7,000 years ago European skin started to lighten . And of course as is the theme with evolution a lot of people probably died. But over time we slowly got lighter skin because of our cereal rich diet of these Neolithic farmers That cereal rich diet, which means grains that lacked vitamin D, did with Europeans rapidly lost their dark skin pigmentation. So they could get a different level of vitamin D into their bodies. And that happened only once we switched to agriculture. Although it was originally thought it had to do with UV radiation in Europe versus Africa. But turns out it was a way earlier than that. Oh, or way later than that. It would have happened a way earlier if was about UV radiation. The end, the moral of the story is: We learn lots of things about humans over time Through small discoveries made in caves, buried for thousands, millions of years underground. And those give us little clues as to where we got to where we are now. The overarching theme of evolution is in the end, a lot of people have to die for us to adapt on a global scale. What are we going to learn about ourselves next? If you wanna check out our next episode make sure you subscribe to TestTube Plus And while you are waiting for tomorrow's episode make sure you check out our previous episodes which talked about how we got to be human in the first place. We started as squirrels, more or less. You'll see. Go watch. And thank you again for watching TestTube Plus. I'll see you tomorrow.
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