I don't know if I recognize any of your names or not, it's been a decade or two. I remember corresponding with Marc V. a lot back then. I stopped corresponding because I gotten to my understanding and the arguing about details didn't interest me. Still doesn't, for that matter. I occasionally send off notes to Elaine, but never hear back; alas…
My take on our water-side residence hasn't changed much over the years, but I've come to new understandings about bipedalism. I write a blog, Ape Shit: A Littoral View of Human Evolution http://apeshit-mathiesen.blogspot.com/
where I spiel on at length. My approach to the question has been from a social science perspective. I looked at demographics: where do we live now? Where did we live in the past? From a demographic standpoint, we all live pretty much where we did a few hundred-thousand years ago: in a warm spot down by the water, potable and otherwise. Being unable to physically adapt much to colder climes, we learned to recreate our home clime through clothing, housing, and heating. Most of us have remained in close proximity to navigable water, and virtually all of us live within a hundred yards of potable water. Those who don't, spend an inordinate amount of time trucking water back and forth. My standard line is, nobody lives in the desert, everyone lives at the oasis. Likewise, no one lives in the savanna; everyone lives by the water-hole. There are many reasons to live by the water-hole, the "edge effect" being primary. The edge effect says that the biomass is greatest where two ecosystems meet. The strongest edge effect is between aquatic and terrestrial systems. I believe we were/are the smartest ape and knew that and hence chose to live where the edge effect was the greatest, where the omnivore's food supply was the greatest. It was taking advantage of the edge effect which "hooked" us on water, as it were.
We've never gotten over that addiction and it's that addiction which keeps us clinging to the coasts. If we were truly a savanna animal, our big cities would be where we were the most comfortable, out in the savannas. They aren't. All big cities are built on waterways and most are close to the sea, if not bordering it. The savanna model requires two changes of habitat: from the trees to the savanna, and then from the savanna to the water's edge. The water's edge model only requires the descent from the trees and the descent puts us where we currently live. Lucky us. I believe Occam's Razor favors my argument. I also argue, that living in the close proximity of water that we have, for as long as we have, would account for all our aquatic peculiarities. No one has ever denied that, so it seems an open possibility. Why must we have been more aquatic than we currently are? What drives that intellectual need, beside sticking with what one has already said? I can see where a few million years of growing up by the water would favor good swimmers. And dealing constantly with the water may well have affected our anatomy/morphology.
But I don't think it's why we stood up. Standing up was useful when dealing with water, but not useful enough to make us even habitually stand up, I don't think. I've thought a lot about how advantageous wading skills would be in enticing us to become upright on land, as well as in the water, and it just doesn't seem likely. The dental records are speculative but nothing's pointing to reliance on water-lily tubers, for example. More point towards meat.
Which bring me to a point about evolution. Contrary to popular belief (and I mean "popular among scientists"), no evolution is driven by pressure. Evolution is driven by opportunity, and it's almost always driven by an opportunity to eat. The forest that were disappearing under us, were disappearing from under the chimps and gorillas, as well. We stood up, not because the forests were disappearing, but because we changed our diet: we began to eat more meat. We began hunting. And hunting was valuable enough that it was worth standing up for. Permanently. Two factors drove that. 1) To be a successful hunter, you have to have your tools at hand at all times; you can't see an antelope and then run look for a stone or a spear, you have to be at the ready. 2) Like all predators, once we started hunting, we could no longer have roving camps; the kids can't joint adults on a hunt. We built seasonal—at least—camps to where we brought back the kill. In our arms. Those hunters better able to stand up, carry tools, and carry game prospered.
We're talking six million years back here, to the split between us and the chimps. We stood up to go hunting. And we decided to make camp down by the river. That's the littoral interpretation of human evolution, the demographic theory.
That's how I see it, anyway. Thought I'd through that back in the ring.