I prefer to use science and facts as my criteria for defining the human species. Morality and politics are philosophical, not scientific. Science can tell us what is, and how to do things. It cannot tell us what we ought to do.
The murderer who is executed belongs to the human species. It is not an organism's biolgical species that determines the moral principles related to it.
Laws and morality pertain only to rational/volitional beings. Man is defined as the rational animal.
Rights pertain only to beings capable of making choice.
Those who want to replace moral principles with so-called "science" are neither scientific or moral.
Hank
You weren't writing about rights, you said that human beings begin life at birth. That is, indeed discussing what human beings *are*.
However, if you believe that
" Laws and morality pertain only to rational/volitional beings. Man is defined as the rational animal.
Rights pertain only to beings capable of making choice,"
then you deny rights to infants after birth and anyone who is delirious and all the ranges of permanent and temporary mental impairment, such as stroke victims and some of those Parkinson's patients we keep hearing about.