Why can't we transplant brains? First of all, we should look at what the brain actually does. This thing inside our skulls that weighs on average about 3.3 pounds is larger in humans than any other vertebrae when compared to body weight. That's why we are so brainy. The busy brain is our command center for our nervous system, which takes in data from our body and gives directions to our muscles. In fact, it does so much work, it requires about 20 percent of our energy to run it. When we are brain dead, we no longer have any neurological activity. With the help of machines, we can be kept alive for a short time, but within a week, the body will not be able to function. While we may still be alive in some sense for that week. we are technically dead when the brain is dead. Some good news is that during the time we are kept alive, some of our other organs can be donated. But why can't we accept someone else's brain. When we transplant something such as a heart surgeons use a mechanical pump to keep blood flooding through the body while the new heart is being put in. The new heart is then connected to the major blood vessels, and this might take several hours. You'll stay in the hospital for one to two weeks, and if your body doesn't reject its new heart, it's said 87 out of 100 people make it through the year, and 60 out of 100 get through another decade. So, wouldn't it just be possible to open the skull and connect a new brain where the removed brain was connected?