The Aquatic Ape Theory
I subscribe to the aquatic ape theory of evolution and have for some time now. Yes, instead of the traditional belief that humans evolved from apes on land in a quickly vanishing forest habitat; I believe that instead of taking to bare land, where our tree dwelling ancestors would of been clumsy and slow, we took to the water for protection.
In the savannah theory, humans take to the land, and learn to walk due to the increasing distances between each tree. Picking up sticks and throwing stone to defend themselves, an ape in theory could survive, for a while. But there are many unanswered questions and missing links which we just can't explain using that theory. For example where did we get the fatty acids that are required to build larger brains? These acids do exist in raw meats, but in limited quantities in land mammals. And do you really think that a clumsy ape could evolve quickly enough living on the land, to be able to go from defending himself against lions and hyenas, to becoming a primary hunter on its own?
I can't see that happening. We are not some super race, no matter how much some of us want to think we are. We are just another mammal, who is in a fight for survival, just like any other mammal. We have just been quite lucky with how things turned out.
What likely happened was the following:
Apes began living in a semi flooded forest area, possibly of brackish water (mixed salt and fresh water). As the trees around them vanished over the many thousands of years, they evolved to traveling and in fact living in the water. Able to take to the trees was beneficial to surviving croc attacks, but the few trees remaining were not enough to supply their food source. Taking to the water, the disadvantages of gravity seem to disappear as it helps support much of their weight. This helps them learn to walk upright, keeping their head above water while they use primitive spear or corralling techniques to collect fish. Fish DOES have the essential fatty acids for rapid brain development, and there is no doubt that these apes ate fish in order to get our brain as large as it was.
Over time we became more comfortable in the water, spending more time there as we learned how to defend ourselves from crocs with spears. The water also has the advantage of helping to cool the body and providing safety from lions and other predatory land mammals of the period in that geographic region. With the final trees disappearing, and the population of aquatic apes expanding from its original area, the apes began living solely in the water.
Loosing our fur, we became more steam lined, and our now developed legs were capable of pushing us through the water with our webbed toes (which is a genetic trait that many people still have). We retained the fur on our head for protection from the searing sun, in the exposed waters of the savannah. We also began to loose our sense of smell, which still to this day is very weak when compared to most other land mammals. Replacing the sense of smell, was our ability to breathe underwater. We evolved the unique ability to hold our breath. And on top of that, our body also evolved the ability to naturally slow our heart rate while we are underwater (which it still does today). Still to this day, some humans can dive for upwards of 6 to 8 minutes at depths of 50 feet, without any breathing apparatus. Just simply holding their breath.
Why would we loose our sense of smell? Well, in the water, stuff doesn't really smell. Using scents for mating and territory was no longer possible, as our scent glands were often under water, and if we could mark something, what would we mark?
Well, the very strong scents caused by the sebaceous glands during puberty, can be detected through water still. with the glands being located in the upper body, they are often exposed in shallower waters, and since it emits a water proof oily substance (used in seals for waterproofing), it will not be washed away by water. That, along with the ability to blush, a clearly visible sign of emotion above the waters surface, helped us know when mating could occur. Mating could of happened in a variety of positions, but a face to face position, with the females legs around the hips of the male, while standing was likely the easiest in water.
We have a descended larynx, which is partially evolved to suit underwater environments. This descended larynx is the key to our ability to speak now, and is unique in design, somewhere between a fully aquatic mammal, and a land mammal.
Child birth is also interesting. At birth, human babies can float, and swim. No other land mammal has this ability. Water birthing is still a common practice today. A few other interesting features are our eyelids. We do not just have 2 eyelids per eye. In fact we have the remnants of a third eyelid near our tear duct which used to sweep across the eye horizontally. It no longer functions, we no longer possess the muscles to operate it, but it is still there. Why would we have an eyelid which sweeps horizontally? Maybe it was a thin layer of skin to protect the eyes under water?
We also store body fat. Why would we store body fat in the Savannah? Is that wise to do in the hot sun? In the water it helps keep us buoyant, and helps insulate us. Like fur. But on land, it is otherwise pointless, and a waste of energy to produce it.
We also sweat. Why would a mammal living on the Savannah sweat? wasting valuable water, and dehydrating quickly. This makes absolutely no sense what so ever. But wait... Hippos sweat, Elephants sweat... Why? Well, this is to remove excess salt from our systems, which is caused by these mammals spending much of their time in silty, salty Savannah waters. We actually share many more of the above adaptions with hippos and elephants.
Sure those supporters of the Savannah theory, will claim that there are counters to all of these. But many of these adaptions only make evolutionary sense if the creature is in a water based environment; not in a sun scorched Savannah full of predators capable of running at speeds in excess of 70 mph.
Eventually, our legs stronger, our back stronger, and our arms shorter, and better able to handle instruments, we moved back to land, this time with the ability to protect ourselves, as we moved onto land and used spears to protect ourselves, and eventually to hunt land mammals. We evolve to settle in tribal villages near our home... the water.
Moving from the trees to the Savannah without the water phase would of been practically impossible. Our spines and legs would of made it so awkward for us that we would not of been able to run from predators, let alone chase down any kind of prey. And in the Savannah, you know if we did manage to kill something, the larger predators would of been on us like what on rice, trying to steal our kill. How would we defend ourselves? Likely story.
But I suppose we all like to believe that we were some magical heroes, who slayed huge beasts and rose up to conquer all animals below us. Well, that makes a good work of fiction anyhow.
From how I see it, the aquatic ape theory has far fewer holes in it then the Savannah theory does, and the puzzle fits together nicely to paint a overall picture of how we got from a tree dwelling ape, to a human capable of flying to space.