I wonder how transportation would have evolved? And what sort of vehicles we would have today. Better? Worse? Or just different?
Which (on a totally unrelated note) pops a question into my head: What is that novel where a planet is rotating at just the right speed, is all land, and has a habitable band in the terminator zone?
A civilization somehow develops there and the cities are on giant crawler vehicles that move at a constant speed to maintain position. If they go too fast or slow, they might get whipped out of the "zone" and have to go through a 500C roast on sunward side, or a -200C darkside cold soak.
Well; the idea is interesting, but hardly scientific. 40,000 years ago; the method of transpotation was walking; so if the water/land ratio was reversed early Humans would have spread more widely across the arable land. But is there even any value to the question? We know Earth DID NOT evolve in that fashion. We can seculate but is that speculation anything more than idle dreaming? I suspect not.
True. But after a certain point; idle dreaming must be replaced by scientific thought. I am MUCH more interested is the geological changes required to turn every bit of land into a water domain. The Humans - assuming any would survive which is unlikely - would come later.
This is a poor map of what Earth would look like if the topography were inverted. For starters, the 'mountains' and soforth on the 'former' seafloors do not correlate to actual bathymetry whatsoever. The maps made by the author of Planetocopia are far better in this regard. Here's Earth with inverted topography and enough water added to roughly maintain the old coastlines;
The first thing one notices is that water has also collected in the depressions that 'used to be' mid-ocean ridges, seamounts, other examples of submarine topography, etc. There's nothing special about the 'continental' depressions- disregarding rates of evaporation/precipitation, water will collect at any low point.
The amount of water needed to 'fill up' the inverted continents is arbitrary and much less than Earth's total water. If one inverts Earth's topography but maintains the same amount of water, one gets something more like this;
Which demonstrates just how platform-like the continental plateaus are.
Quite a bit of the artwork on the site of which Planetocopia is a part is quite odd and not work-safe, but the planetocopia maps and globes themselves are quite impressive and I can't think of anything of their sort elsewhere on the internet. They've also created renditions of Earth with poles in different locations, as well as fictional planets, a deglaciated Earth, and a terraformed Mars and Venus.