In this video, I would like to put the emergence of agriculture in a bigger perspective. But in order to do so, I would like to zoom in first to this structure, Gobekli Tepe. As I told you in my previous video, this ritual center was built more than 11,000 years ago in what is now, Turkey. And consists amongst other things, out of huge and beautifully decorated T-shaped pillars. Why did people build it? This question is particularly intriguing or so it seems to me because Gobekli Tepe is the first known structure of this size ever built by humans. In contrast, earlier hunters and gathers generally built much simpler structures, like our primate cousins do. Out of these primate cousin groups, orangutans are the more elaborate builders, but they do not build much more than nests, in which they sleep once and abandon when they wake up. In fact, there are relatively few larger brainier animals that built. Building is actually much more common among birds and certain arthropod species. So why would that be the case? The answer to that question is very simple. Building is expensive. It is not only expensive to actually build a structure, but also, to use it. Both building and using a building require moving things. While building, it is necessary to move building materials, and while using a building, it is necessary to move yourself. And this can be particularly costly if you need to look for food or mates at significant distances from your building. And need to travel back to use it, much like we need to do when coming home from work, the grocery store, or in night outs. Because building is expensive, in many situations, animals have developed alternatives for building. For instance, they grow furs to protect themselves from the colds, claws to protect themselves from enemies, or colorful fetters to impress mates. When you study animal building in more detail, you will find that there are only three types of building, three types of situations in which building is worthwhile. Situations in which animals can build cheaply. Situations in which they can use their building cheaply and situations in which they can use their building capacities to show off. Animals that can build cheaply have standardized their building practices so they don't need big energy consuming brains and builds with efficient and sometimes even recyclable materials. The best example of such animals are spiders that build their webs in standardized ways. With what, up until recently, was the strongest building material every developed, silk. Animals that can use building cheaply, stay in place more frequently or for longer periods of time, which means they don't have to travel long distances just to be able to use their building. And examples of such animals are animals who take care of immobile offspring such as eusocial insects and birds or rodents with altricial young, and animals that stay close to a specific food source such as, again, eusocial insects or beavers. Animals that use their building capacity to show off, do so by demonstrating that they have a lot of energy to spare by wasting it on the construction of an imposing building. And the best example of a non-human/animal excepting this kind of behavior are bowerbirds, some of which build hatch that are several times their own size. They subsequently decorate with organized collections special objects just to impress mates. So, what is all of this have to do with Gobekli Tepe and the emergence for agriculture? When climates change, after the end of the last ice age, and certain regions became particularly productive. People in such regions may have been able to stay in particular places for more frequently and for longer periods of time because they no longer needed to roam larger areas to obtain enough food. As a result, building in such places may have become more attractive. Because it may have been easier to actually use the buildings. So, living in smaller territories, and perhaps even settling down more or less permanently may have encouraged humans to build structures ranging from more elaborate camps, or villages to monuments like Gobekli Tepe, just like sedentary or semi-sedentary light weights, and encourage other animals to build. Of course, there are other factors that also explain why people build Gobekli Tepe, such as people's world view, and social structures. I mentioned it in my previous video, but I although I think these effects are very interesting. I won't tell you more about them and instead, I want to talk a bit more about the idea that it's cheaper to use buildings when you stay in a place more frequently, or for longer periods of time. Because I think this idea could have important implications for the emergence of agriculture. I think so because perhaps it could also be applied to aspects of agriculture beyond building villages and monuments. It could for instance be applied to domesticated plants and animals, storage food or beer, tools, artistic expressions and other things that you cannot easily take with you all the time. After all, it only starts to make sense to use all of these things when you are near them often and long enough. In other words, before people started living in territories small enough to allow them to stay in one place frequently or for longer periods of time. It wouldn't have been very efficient to develop many of the key in ingredients of agriculture. This is of course a very simple argument but nevertheless, it is often overlooked. Perhaps, because most of us are so accustomed to secondary lifestyle that we take it for granted. Or because for many of us, traveling has become so cheap that we can no longer imagine that it may have been a factor that has influenced the emergence of agriculture. This is too bad because this simple argument raises some tantalizing questions. For instance, it is dragging that a number of other animals that also stay on place more frequently or for longer periods of time have also developed more complex material and social structures. Some termites, ants, and ambrosia beetles have even invented agricultural practices. All of them grow fungi, some of them in very elaborate ways. And some ants even heard aphids. So it could be very interesting to think about how and if the development of agriculture in different species, including humans, may have been influenced by how often and how long they stay in one place.