[MUSIC] Let's go to the Models Library and go to the next launch Sugarcape number 2, which is called Constant Growback. And in constant growback, let's see in info, it's also based on implements Epstein and Axtell's Sugarcape Model is described in chapter two of the book. It differs from Sugarscape 1 Immediate Growback model in that the growback of sugar is gradual rather than instantaneous. Well just a slight change in modelling assumptions and it also makes sense, resources don't grow back immediately. They take some time to grow back and let's see what this little change in making assumptions a little bit more realistic. What the effect of this will change is on our model outcome. So, everything else the same, we start setup and we go, agents move, you can also go a little bit faster, and we see, the four terrorist is actually a building the model keeps on going on going. We already know I'm in 270 time steps and we see the population actually went down quite a bit and they keep on moving and moving. So they do not find a stable point where they sit put and also, yeah, there are some income groups here but something in between them as well. Why do you think agents don't stay still and and keep on moving in this model? That's because the ones who see more, once they ate all the resources which are at this spot, will move on to the next spot, right? So if you also see for example, the vision of them, we see well there are some with a very high vision. And basically, yes, they keep on moving, so once they ate it, they move on to the next one, eat it, and they don't stay put there where there's nothing there because it takes some time on this patch for it to grow back. That's why they constantly, by the agent constantly keep on moving. And then we have kind of like three income groups that are emerging here. And another interesting thing I think the population actually, I think I remember in the other one we stabilize at a population of 250, here we have a population of 220. So actually, less agents made it at the end, maybe that also had an effect on the vision and the average metabolism, let's see. Okay, so in this and the constant in the sugarscape number 2, the population is down to 220, starting with 400 at the beginning, and the vision increased to about 4, and the average metabolism decreased to upon 1.7, 1.8, okay? Let's run with that 220, 4, 1.7, 1.8. Let's compare that with our previous simpler model, the sugarscape number 1, and see here, what do you think? Do we have less or more evolutionary pressure in the second model than in the first? Let's check it out. So we start with 400. The population is decreasing, now it actually stabilized we can also take the inventory, nothing is changing much anymore. You have a flat line here, yes 250, so it went from 400 to 250, whereas the second model where where sugar need some time to grow back went down to 220 and also the vision went up to 3.8 only, and the metabolism went down to 1.9 only, yeah, so actually there's a stronger evolutionary pressure in the second and Sugarscape 2. You have to be fitter in order to make it. Some will die and at the end the fitter survive, which then brings up the average vision and it's still increasing, it's still increasing even so 200, 300 periods in, it's still increasing. There's still some evolution, happen and metabolism still goes down a little bit. So there's more evolutionary pressure, when the environment is also changing, because a changing environment needs intelligent and adaptable and adjustable agents in order to be able to deal with it, and that accelerates evolution.
