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> Isn't the human length from infancy to adulthood much longer, so as to be
> qualitatively different, than any other species' ?
Part 1: You can skip this and move to part 2 if you wish....
Charles and Jim,
Before I attempt to answer these questions, and provide a response to Jim, I want to make a disclaimer and state my general point of view, which is _my_ point of view on evolution, culture, and historical materialism. In other words I have no "proof" for my world view, it is simply what I think is a reasonable and rational way of looking at things.
First the disclaimer. I am not an expert on sociobiology, anthropology or historical materialism. I just read a lot. One reason why I study all three is because I am interested in the relation between kinship systems and the rule of law in ancient city states, and it has led me down some strange paths. One reason why I study sociobiology is because I am interested in army ants and have been since I was a boy. Sociobiology provides the best insights into the social insects and that is how I came to it originally. I had largely accepted S. J. Gould's and Lewontin's condemnation on sociobiology. It wasn't until later that I found some of Lewontin's condemnations correct in general but often wrong in specifics and that I discovered that Gould was often open to many insights that should be termed sociobiological.
Next my general world view.
Evolution is about failure; culture is about success. This is a slogan to keep in mind.
To put it another way evolution is about relative success against a background of all that failed. died off, went extinct, worked in a way that was worse than an approximate fit to the ecological niche. In a biological system nothing ever works perfectly. As Gould once said evolution is a vast hecatomb of sacrifice of the biological losers.
On the other side I think culture is about relative failure against a background of hoped for "perfection." This is because what we make, individually and collectively, all of our cultural artifacts and attempted expressions, we are always aiming, teologically, for some ideal we have erected in our imaginations. Here I am influenced by Ernst Bloch and his notions of art and utopia, but also in another way by Marx.
"A spider conducts operations that resemble those of a weaver, and a bee puts to shame many an architect in the construction of her cells. But what distinguishes the worst architect from the best of bees is this, that the architect raises his structure in imagination before he erects it in reality. At the end of every labour-process, we get a result that already existed in the imagination of the labourer at its commencement. He not only effects a change of form in the material on which he works, but he also realises a purpose of his own that gives the law to his modus operandi, and to which he must subordinate his will." Karl Marx - Capital.
We never reach the "perfect" ideal we erect in our imagination. Our mental power to imagine, what ever it actually is, I take to be a result of our biology. Thus one reason we can never reach the ideal we erect in imagination is that we are bounded by material circumstances both biological and sociological.
For me Marx's insights provide a bridge (rickety, tentative and without sturdy theoretical suspensions, but a bridge none-the-less) between evolution and culture. The scare word "sociobiology" is simply a small potential support for that bridge.
Another aspect of my world view is that the mental is a special case of the biological as the biological is a special case of the physical.
By homology, the cultural and the sociological are special cases of our evolutionary history. The idea that these might be emergent properties (as I think) and not necessarily reducible, through theory, one to another is not germane to the general principle. This is another aspect of my world view, though I think that he previous sentence is, in principle, an empirical question. And though I may make the assumption that what we call the mental is in the final analysis an aspect of the physical, it does not mean that I think that we can produce a theoretical model that explains all of this. My study of physics, has made me realize that theoretical models are very, very narrow and can be explanatory only when they are narrow.
None of the above answers your questions but it does give you some indication of how I brought myself to an interest in these problems.
Jerry