Have you ever thought about what it would be like to not recognize anyone around you? Well this is a very real problem for those with prosopagnosia. This happens when damage to the fusiform gyrus takes place which causes the person to no longer recognize faces. The person cannot even recognize their own family or friends; this would create a very sad and lonely life.
So why does this happen? Each part of the brain has a specific duty. Although things such as memory can occur throughout the brain in different places each lobe or part has a certain "job" to do. For example the parietal lobe is in charge of the bodies "topographical map" where each part of the lobe represents a different part of the body.
Facial recognition is done in the temporal lobe so when the temporal lobe is injured it is no longer able to perform this task. The temporal lobe is located on the sides of our brain and has other functions besides face recognition. This part of the brain also plays a role in our ability to hear and understand language, as well as memory, which accounts for why we are no longer able to recognize someone if damage is done. The brain has many functions and needs to be protected, so now we know why we must wear a helmet because without our brain we'd be lost.