Subcutaneous layer of fat typical of marine mammals, relatively hairless bodies, long flowing hair on both sexes (with which to tow small children when foraging unencumbered in the shallows), suggest coastal origin. Very little residual features to suggest savannah...most primates retain tree climbing agility (to escape danger) whereas modern humans seem to have little at all, also suggesting a coastal origin...they could escape land preditors by entering the water.

I don't know.

I always thought that we were in the forests (our opposable thumbs were an adaptation to holding tree branches) and then something happened to force us out of the forest. Once out of the forest, we started working more on our bipedalism.. needing to stand up so we could use our hands to carry things for moving from one place to another. We likely stayed as close to a water source as possible, cause you know, water.. but I think most of our traits that gave us an advantage came from the forest and then loss of forest.

Aquaman.....yum...... wait, what was the question?

That most people are have mostly hairless bodies and that modern apes stand on two legs when entering water, suggests to me that for a long time most of our ancestors spent a lot of time int eh water, and eventurally came back and lived lives mostly on land again. Kind of liek how Whales for a while had ancestors who lived on land, but they evolved back into the water.

It is possible that evolution evolved in both the land and water environments with two different branches and they eventually interbed back into a single branch, much like modern humans are the product of probably about half a dozen evolutionary branches that have interbred back into a dingle branch. Most humans have soem Neanderthal DNA in theri genes. As tiem goes on if we are able to extract DNA from other human evolutionary branches that have disappeared, we may find their DNA in our genes as well. I suspect first groups wandered out to remote areas and evolved suited to thri local environment, and then later other groups came along and there was interbreeding going on, and this probably happened over and over again, which is why humans are so versatile and able to adapt to many environments so easily... because a one group or another of our our ancestors evolved for a while in avirtually all available environments.