I can only assume you are not using the scientific definition of "species"
and are lacking in access to the proper resources, then.
The matter is pretty much settled, and has been for at least a few decades.
There is (rather obviously, even) no sentience at all behind the attributes of the human body. It just happens that in the tree of vertebrates the human body is one of those who developed from mutations and speciation and happened to be viable enough to survive to this day.
http://tle.westone.wa.gov.au/conten...nce_3b.zip/content/003_mechanisms/page_03.htm
http://www.wisegeek.org/what-is-selection-pressure.htm
The development of the specifically human phenotype was utterly accidental. Its success at surviving and reproducing when competing species failed at it is not accidental, though. It is a consequence of the selective pressure of the environment.
Had the environment been sufficiently different, humans might well never have developed in the first place. Or they might have developed only to become extinct at some later point.
Or the specific mutations and resulting speciation might have been different by sheer luck of the draw, resulting in no human beings at all. Some other species might have developed sentience, or perhaps no one would.