When does a human being begin having rights and responsibilities? That is, when does a member of the species [i]homo sapiens[/i] become a person? This is asking about the relationship between a biological concept and an ethical concept. I'll leave defining the concept of a human being to the biologists, but will explore the concept of being a person below.
First of all, by "person" I mean "a being that either is or must act if it is a moral agent". A moral agent is a being with free will. Free will is being able to influence the probabilities of events while not being under the influence of external factors; that is the negative definition. Positively, having free will is giving the moral law to oneself. Free will also means rational autonomy, which is having a will which is under the influence of only itself and its rationality. To contrast, a moral patient is a being which can suffer.
Now, basic to the original question: when does a human being become a person? I would argue that a human being becomes a person when it is capable of reflecting on its moral agency. That is, when a human realizes that it is a person is when it is a person. This requires a human to develop a level of consciousness which allows it to think its own agency; that is, when a human cannot but believe is has free will is when it qualifies as a person.
