It doesn’t make sense to claim that you can turn to social construction for meaning but not to lived reality.
We actually have an interesting case of incommensurability here. You insist that language is a "communicative capacity," just like other animals have "communicative capacities," only far more powerful and complex. You have to see it that way because it's the only way to vindicate your a priori claim that evolutionary biology can explain everything. But you don't know, and can't "prove," that language is really just a more advanced form of what animals have. If we think about language as *different* from "communicative capacity," not just "more" of it, we will be led to other possible explanations for its existence. The difference, on the one hand, lies in what linguistics have called the "arbitrary," or purely conventional, nature of the sign--there's no reason for the sound "cow" to represent that particular animal, which means a community of language users must have "agreed" (an unsatisfactory word here) to have used the sound "cow" in this way. This implies an event, in which at least two people are attending toward something in some new way and letting each other know that they are doing so in a way that they could repeat. Such an event can't "violate" any biological "laws," of course, but it is central to language and irreducible to biology. Another indication of language's *difference* (rather than its *moreness*) is all of the non-communicative uses of language, some of which are more "basic" than its communicative uses (if we understand "communication" to refer to the provision of "information," the usefulness of which is presumably already "known" by the recipient). A man and a woman stand before a priest, who "pronounces them man and wife." What has been "communicated"? Biologically, and "factually," nothing has happened. Nobody "knows" anything they didn't know before. And yet the two have a new "status," recognized by the community. If two individuals greet each other in some highly conventionalized way (like tipping their hats) what has been "communicated"? When the leader of a town council announces that "the meeting has come to order," what has he "communicated"?
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It may very well be that you will be able to offer elaborate evolutionary biological explanations of these practices in terms of the "selection" of genes that enable the organisms in question to "adapt" and "survive." (The town council leader is really expressing his dominance, or whatever.) This could certainly keep lots of psychologists and biologists employed if you succeed in pushing out the more literary postmodernists. But you will come up with these explanations because they fit your "model," not because you are interested in why humans have such things as "greetings," "christenings," "baptisms" and other fairly non-communicative practices. I suppose, like many other animals, humans construct abstract models of reality that they want to complete, defend, extend, and convince others of.
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Interestingly, it is possible to accept both the originary hypothesis and evolutionary biology--GA, in fact, must assume that humans didn't exist at one time, and then they did, so there must have been some prior primate species that we "came out of." Most people in GA probably more or less accept the Darwinian approach, even thought it's not strictly dictated by the originary hypothesis (it's just something we're not so interested in arguing about). Certainly, language would have made the "advanced primate" that invented it more "survivable." But evolutionary biologists seem to resist the notion of *difference* rather than *moreness*. This is because, far from being a neutral and objective science, evolutionary biology represents political and moral interests. These interests may be diverse (there are obviously liberals, leftists, conservatives and neo-Nazis who accept some version of it) but it does come down to what you indicate above--abolishing all talk of "transcendence," aesthetic, moral, intellectual or sacred, in the name of a fully "manageable" human community. If everyone is reducible to biology, we can reduce everyone to biology. It's an attractive proposition for those doing the reducing.
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You want to call what is different about language employing language "to unique human ends due to its incredible intricacy combined with high human intelligence, such as multi-generational oral data storage," but calling oral traditions "data storage" tilts the filed towards assimilating human language to, in this case, computers--your very vocabulary revokes the uniqueness you grant. You say everything is reducible to biology, but also that "I do not think the study of biology alone is yet enough to fully understand humans. I like to combine the evolutionary science with other areas too." Until you've done the "combining," how do you know? What, so far, seems to fall outside of biology?
I'm not referring to your interests, but to those of evolutionary biology as a field--but, more interesting, where do you think evolutionary biology comes down on the difference between your own disinterested inquiry and the interests of the field as a whole? When some individual arrives at conclusions inimical to group interests, how do our genes know whether we should kill him or make him king?