Although the three comments were somewhat hurried and hence a bit unorganized, the thrust is clear, and it raises a very interesting and important point. Briefly [since I too am on my way to class -- the first meeting of an Adult Education course on Plato's Gorgias at Duke University], the natural growth and development of a human being from infancy to maturity is unlike that of animals [with an important caveat to be mentioned in a moment]. The development of the human infant is radically underdetermined by genetic inheritance alone, requiring as well the transmission of a set of behaviors, understandings, expectations, etc. that we can call culture. An adult human who has never internalized this set of cultural elements is not a "natural man," as Rousseau and others would have it. He or she is what used to be called a "wolf child," a wild creature radically unable to function successfully and lacking anything that we would recognize as a character or personality. This is in contrast to the manifest grace and coherence of adult animals. [The caveat is that we see rudimentary elements of this in animals, which we would expect, since there must have been a slow transformation over many millennia from pure genetic determination to the full-blown transmission of culture.] Now, this cultural element in human development is unavoidably ideological, in the sense that it encodes components of domination, exploitation, rationalizations of the same, and so forth. So a pure biology of human development cannot, by its very nature, capture what is distinctively human.
A nifty example of the caveat from my safari. One day we came upon four lions lying down, which, our guide told us, were a pair of mothers and daughters. One of the mothers got up and climbed up onto a horizontal branch of a nearby tree. This is very unusual behavior for lions, though not unheard of. The daughter then followed the mother up into the tree, but neither of the other two lions did. The guide said [these guys go out every day of the week, and get to know the lions individually ] that the mother had taught the daughter to climb trees, and he wondered whether the daughter would, in turn, teach her cubs to do the same when she had some. You see the point. Here was a tiny bit of non-genetically determined culture being born.