I don't think that environmental influence and biological influence are at odds. I suspect that we do adpat a style of thinking that is required to navigate our environment and subsequent biological changes follow, allowing us to better cope with environmental demands. In a sense we are smarter today because our enviornment demands it but the basis of our growth lies in the lessons our ancestors passed down. There already seems to be evidence that kids of this generation are better able to think spatially and this may be attributed to video games. We are an evolving species. Our ancestors weren't dumb in thier time but most wouldn't cut it in ours. Just as when we picture the future we envision a highly developed people that would understand concepts far and above what we currently comprehend. Those unique individuals who think at a level beyond what is environmentally demanded in thier own time, help pave the way for mass changes in thinking and increases in intellect. The changes may be measurable within just a few generations and as we become more metacognitive, may increase even faster. We are training ourselves to think better, having gone from manipulating a concrete world to manipulating a world of abstraction.