Definition of human being?

Can anyone tell me the definition of human being with a reliable link? Im doing a research/argumentative paper on stem cell research. thanks!
Answer:
If you want to define "HUMAN BEING", it is basically a member from the species Homo sapien.
For your argument purpose, you need to define "PERSON".
The argument with stem cell research is not whether we are using a human cell. It is an argument of whether we are killing a "PERSON".
If you are killing a person to achieve the goal of treating other person, then it is unethical. A good example would to to steal someone's both kidneys to save live of two person but sacrificing that one person. Unethical in that case.
However, if you are taking something that is not a "PERSON" yet and use it to treat a person or a group of person, then it is OK.
A "PERSON" is defined, as far as I am concern, as someone who has the anatomy to feel and think - must have nervous system. Then that someone must have the ability to think and feel with those nervous system organs.
If you put it that way, the stem cells are not a "PERSON". They are a group of cells made from fertilized eggs and not yet organized to form a nervous system. Using it for treatment of cancer, Parkinson's, Alzheimer, etc, is justifiable, as far as I am concern.
On the other hand, taking organs from mentally regarded or those in coma, as well as late stage fetuses, are not ethical.

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Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: "wise man" or "knowing man") in the family Hominidae (the great apes. Humans have a highly developed brain capable of abstract reasoning, language, and introspection. This mental capability, combined with an erect body carriage that frees their upper limbs for manipulating objects, has allowed humans to make far greater use of tools than any other species. Humans originated in Africa about 200,000 years ago, but they now inhabit every continent, with a total population of over 6.6 billion as of 2007

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