As you probably know, the brain is not uniquely human. Almost every other animal on this planet possesses some kind of brain. Some animals, such as the chimpanzee and the dolphin, are said to be as smart as young children. However, the evolution of the brain predates both of these animals. Lets take a trip back to the prehistoric time when reptiles ruled the earth.

The reptilian brain, which is the lower brain/brain stem, is the most simple of the three "brains" that humans have. This is the brain that was passed down from the reptiles long ago. The main fuction of this brain was for survival. It completes tasks that are automatic, like the beating of the heart, breathing, and other simple functions. Some say that this is the most important of all the parts of the brain, because without it, even for a few minutes, you would die. When someone is "brain dead", or living with no conscious thought, this is the part of the brain that remains alive.

Most things that happen in your body without you thinking about it, or possibly knowing about it, are maintained from here. This is more or less the control center for your body. There are other learned habits that become second nature that aren't hardwired here, but most are. Even if you learn to ride a bike, different parts of the brain help you with this, but the lower brain ties it all together and makes it an unconscious effort.

There are two short-comings of this part of the brain, however. Your reptilian brain has no abilities of consciousness. It also has does not have much in the way of emotional capabilities. With only this brain, you cannot recognize or even acknowledge the existence of others, everything is either prey or a predator. Thats why some parental reptiles don't interact with their offspring, and the offspring don't interact either, for fear of being eaten.

The reptilian brain was the dominant brain for miilions of years. Thousands of years ago, mammals started becoming more and more common, bringing with them a new neurological invention, the limbic system. The limbic system, or middle brain, was the first brain capable of emotion. This was necessary for survival in the new mammals because the mammals give birth to live young. In order to care for their young, there needed to be some kind of compassion for one another. Even some of the earliest mammals, rodents, have emotions for another. In some cases, the parental rodents do attack their young, but that is said to be the rodent form of Post-partem psychosis. When parts of the middle brain are removed from rodents, they no longer recognize the existence of each other and litterally walk all over each other. As you might expect, humans and other higher mammals have larger middle brains.

Do animals have emotion? Where did human emotions evolve from?
How are emotions created?
What role do emotions play in memory?
What is instinct and how is it important?
What is emotional intelligence