Causes and effects of human migration

- [Narrator] In this video, I want to talk about human migration. And when we say human migration, we mean people moving from one location to a new location with the intent of staying in the new location. The first migration I want to look at here is the Bantu migration in Sub-Saharan Africa. And what's interesting about Sub-Saharan Africa from a linguistic or language perspective is that when you look at Sub-Saharan Africa in terms of language families, the majority of people in most of Sub-Saharan Africa speak a Bantu language. And archeologists and linguists who study the spread of the Bantu languages know that the Bantu language probably originated somewhere here in West Africa. So the question that arises from this is, how did this language spread throughout so much of Sub-Saharan Africa? Well, one problem we have when we try to answer that question is that we don't have written records. These languages were not written down at the time that the actual migrations and expansion occurred. But one thing that Bantu-speaking cultures had in common was that they knew how to make and use iron tools and weapons. And fortunately for archeologists, iron tools and weapons tend to hold up fairly well. So they can find these sites where Bantu speakers lived, and they can date the artifacts that they find, and from that they can get a sense of when various Bantu-speaking groups showed up in different parts of Africa, and then from there we can kind of trace the spread. And it looks something like this. And the fact that Bantu speakers had these iron tools and weapons is one of the causes of their expansion. From a military standpoint, if you have iron weapons and the people you are fighting against do not, you're gonna have a really big advantage. They also were able to make agricultural implements, or tools, out of iron. These were stronger, they were more durable, they were better for working with, which helped the Bantu speakers produce more and better food. And more and better food causes increased population growth. And as a population grows in a particular area, that puts more pressure on the resources to feed this population, and that in turn forces people to start to look for new places to migrate to. And I mentioned a little earlier that the Bantu speakers were farmers. And they were growing things like millet and sorghum, and later on they started to raise cattle as well. And what these crops and cattle have in common is that they all tend to do well in what's called a tropical, or a sub-tropical savanna climate. And when you look at Sub-Saharan Africa, a lot of Sub-Saharan Africa is a tropical or sub-tropical savanna climate. So if we look at our spread of Bantu-speaking people in Africa, we see that it actually lines up pretty well with the areas of Africa that have this same climate. So we can see the climate of Sub-Saharan Africa, or at least much of Sub-Saharan Africa, that aligned with Bantu agricultural practices as being another cause of the Bantu expansion. So we know that causes also have effects, and we wanna think about what were the effects of the Bantu migration on Sub-Saharan Africa? Well that first point I made about it was that even today, many many people in Sub-Saharan Africa speak some Bantu language. Now there are several hundred Bantu languages, but they are all related and it does go back to this initial expansion of Bantu speakers. So that's one effect of the migration on Sub-Saharan Africa. The Bantu speakers also brought the iron-working technology that they had with them as they expanded, and so one other effect was that iron-working technology spread throughout Sub-Saharan Africa. And finally, they were bringing new crops and new farming practices into regions where they moved, and this had some effects on the landscape. When you're actively farming an area that's going to look different than people who are living a hunting and gathering lifestyle. The second human migration I want to look at in this video is that of people into the Pacific Islands. And I have a map here that shows the most likely route of expansion that people followed as they moved into the islands of the Pacific over time. And when we look at the Pacific Islands, the obvious obstacle to travel there is that there is a lot of open ocean, and these islands are very small and oftentimes far apart. So, one of the ways that people were able to travel and migrate across the pacific had to do with technology. Specifically, the technology that people had in the Pacific Islands were sailing canoes. And I have an image here, this is a modern recreation of a sailing canoe, but it gives us a sense of what these vessels would have looked like. And you can see that the two hulls and the sail are gonna let it be a little more sturdy, they're gonna let it take advantage of the winds to travel across the ocean. So having this technology was one of the things that allowed people to actually physically move across the Pacific Ocean. So now we need to think about why were people trying to travel across the Pacific Ocean? Well, similar to the forces that caused the Bantu migration in Sub-Saharan Africa, in the Pacific Ocean we also had population pressures. And in the Pacific, we have a lot of small islands. So population pressure becomes an issue a lot quicker at a lot lower population than it did in Africa. We see population pressure as a major cause of migration in the Pacific. And because a lot of islands in the Pacific Ocean don't produce a lot of natural foodstuffs that people can eat, these people who were migrating in the Pacific had to bring food with them. So they would bring plants with them, they would bring things like taro roots or yams, and these were plants that they knew would grow well in these island environments. They also brought animals with them. So, chickens, and this is an image of a Southeast Asian jungle fowl, and these were the precursors to domestic chickens. They also brought pigs, and a breed of small dogs. And the dogs were not hunting dogs, the dogs were a source of food. And rats also tended to tag along on these trips. So, you have people moving to these islands, and most of them are fairly small ecosystems and environments, and they bring these new plants and these new animals, and this has some major effects on the environments where they choose to live. I already mentioned with the Bantu migration that bringing agriculture to new regions can have some impacts on the landscape, and in the case of migration in the Pacific, the animals have even more impact. So the rats, for example, tend to eat bird eggs, as well as get into and eat people's food. And the pigs also compete with people for food. The pigs are supposed to be a source of food for people, but pigs do fairly well if left to their own devices, and they became a competing population with people for food resources. And there's actually a story from one island in about the year 1600, they ended up killing all their pigs because the pigs were causing too much damage to the rest of their food supply. And generally, the people on these islands would find a balance between producing food and helping a population they could support without destroying the island environment, but there were some cases where islands were nearly destroyed because of the effects of human populations living there. Most famously, the example of Easter Island, which is off the coast of Chile. If you have some time to look up that story, it's an interesting example of the impacts that humans can have on an environment. But to summarize, we see a couple common causes of migration. And in both cases, in Africa and in the Pacific, we see that pressures on food resources cause people to look for new places to live. We also see that technologies allow people to move into new environments. And on the effects side, we see that when people move to new environments, that's going to have impacts on the places that they move to. People are going to bring new plants and new animals, and that's gonna have some environmental impacts. And people are also gonna bring new cultures and new ideas to regions as well. So hopefully this can provide you a framework for understanding other migrations that you might look at, in that you can think about what is causing people to move? And once people do move, what impacts does that have?