So let's get started. So this, I guess, is the last lectures for the whole course. So today we'll talk about the gene and the behavior. This is a big topic, okay? Talking about the behavior, it's very complex actions recruit from the whole body. But then we need to think out actually, what kind of gene you want in this behavior. This is quite challenging. Because as you remove the behavior's actually not only involve with one single gene. Actually they need a couple of many, many different genes, all right? Let's take a look the behavior. This photos actually for the left. For this side, there is a dog hunting for a bird. Okay? This is in the dark. Actually the dog carries because this is kind of an experiment. Actually carry that fluorescence actually device and then you can track how the dogs actually move in the dark. Then this is the dog and this is a bird. There you can see the dog actually knew this attack. Follow this trace of the odorant or chemicals from this bird. We know actually that dogs have a very acute sensitive olfactory system to detect these kinds of cues. In comparison, a human, actually, we don't have so sharp olfactory system, compared with these dogs. One reason is actually because it's a dog. So actually, always, the nose is so close to the to the ground, and the most chemicals, actually, are the source. It's actually from the ground, okay, right? So [LAUGH] then this one, there is actually a, A person, So the vision was blocked. And just to mimic the dogs behavior. And very close to the ground is the nose and then also there is a kind of odorant choice. This white line. You can see actually, quite interesting, the movement of this person actually is also kind of zig zag. Why? Why are they moving in this kind of direction? So, the task is actually to maybe use this cue guide is a person actually to find a target here. But the point is why you should follow this kind of zigzag movement. The dog's of course actually is much larger. Any reason for this one, for this kind of behavior? >> As a close data [INAUDIBLE] and the smell is stronger. >> Yes >> [INAUDIBLE] >> Aha >> [INAUDIBLE] the smell is stronger. >> Yep. This is a very good point. So because actually these kind of direction cue. So the direction cue is actually, you need to follow the highest concentration. Then you know actually the sources along this line, right? But how can you know? The concentration is highest at the particular location, you don't know. You need to make a comparison. So you need to move around and you find an area. This direction is actually the strongest one, right. Then you will follow this direction. So that means you need, actually you make a comparison during the tracking. Clear, right? Okay. Apparently, it doesn't matter human or dogs. They use similar strategy. To detect the chemical cue. I guess this also is quite familiar maybe behavior to everyone here. This actually is the quite interesting right? For the ducks, when they hatch out from the eggs, people found actually, it's the first moving target, it's their parents, okay? [LAUGH] What's that mean? It's actually, These ducks actually just hatched out, and then if they saw a moving target, it doesn't matter it's a dog, or cat or duck, most likely they will believe that target is the parent, okay. So of course in the most of case. Is it is actually the true biological parent. Up hear actually update alright. So they follow all the time. And that. People do the experiments is actually you see a person, actually the ducks just follow him to everywhere. Just actually follow the parent. Because actually before they hatch, this person actually sit in front of those eggs and when they hatch will solve the puzzle. What kind of gene or nuerocircuitry controls this kind of behavior? This kind of behavior actually It's quite interesting right? So they do not need to learn, okay. Actually, when they were born and they have this kind of behavior that means this behavior is kind of genetically determined or programmed. Already when they're born and it is neurocircuitry. Wild is just specifically for that kind of function, right? We also maybe mentioned in our lectures before, some animals actually can sleep with half brain. They can one half for the brain's sleep and the other half is awake and that for biological significance is that they need to be a well of the danger okay. So for example, like this kind of behavior, actually for this duck. They can sometimes, if you notice, they can one eye open and the other eye closed. Another thing, actually, one half of the brain is resting. The other one, of course, is actually alerting, looking for the dangers. And also we mentioned actually last time, actually the dolphin is similar. Dolphin because they actually need to breathe and then they will actually when they sleep they will open one eye and also, Looking for the dangers and also floating on the water. And then, the other eye closed. Of course, in this case, the brain, actually, this is the opposite. The open eye, the opposite brain, actually, to this side, okay? This is, if this is the left eye, then the right brain is alerting, okay? It's awake. And then this side, the open eye side of the brain, they're in rest. So this kind of behavior of course we still don't know what's the gene determining this function.