The human brain has an amazing ability to interpret, categorize, and retain information. The brain is an organ designed to take input and use it to create output (a response). The Human brain also automatically synchronizes itself with sensory input such as what you are seeing and hearing. By this, all I mean to say is that the human brain is only the most advanced biological computer that evolved on the planet earth.
You have the ability to think freely and act at will only as a result of stimuli to the brain. Although you may not feel this all the time every thought every seemingly random thought that happens to pop into your head is the result of an input to the brain and creating a chain reaction of electrical impulses that are interpreted as scenes (thought). You learn from your scenes and constantly rely on them to survive. If you were to stop all input to the brain all output would stop (a state similar to a coma in which the brain and organs still function, if not somewhat irregularly, but the subject is inactive).
These statements make the human brain seem somewhat computer like. That is because it is. The brain is a computer and nothing more. Thought is the result of the communication between neurons in the brain. Does this mean that one day our computers will think just as we do?
"... most experts expect human-level AI to be reached within upcoming decades ..."*
We in our modern world sometimes refer to this as Artificial Intelligence (AI) but when the computers that think are created they will be in no way artificial they will be real intelligence. They will be intelligent beings that will be able to think and compute input more rapidly and comprehend it in a way that is much more sophisticated than us. They will not be simple machines or robots, they will be a whole new species, a new form of life all together.
The debate and controversy that arises over the sentient machine in not one that our society is unfamiliar with. In the 17 and 1800's people argued over the concept of slavery. It now seems barbaric to say that it is normal for one man to own another but how is saying that something that can have opinions cannot be alive any different from saying that a slave is not a person? At this point there is only one true question; "What does the sentient machine say when I tell it that I am alive and that it is not?"
Human evolution was and still is affected by natural disasters, diseases and the whim of rulers of vast kingdoms and these factors have all contributed to shaping the chemical bonds of the human genome. A race of technologically based beings would be plagued by similar problems; oxidization and the brake-down of mechanical parts, computer viruses designed to attack the core of their programming and possibly rivals in society. Unlike their human ancestors however, any problem that they encountered with their design could be rapidly fixed.
* Quote by Ben Goertzel, the founder of the Novamente and Biomind computer firms and the non-profit Artificial General Intelligence Research Institute. Brain photo by Gaetan Lee (Creative Commons).