The aquatic theory uninterrupted?

Bernt's evidence suggests brain size is arbitrary. Additionally it is suspected that we use a fraction of our cerebral capacity (some posit as little as 10%) At any rate if our brain was so simple that we could understand it, then we would be so simple that we couldn't...
(that one warrants a )

To change tacks, is anyone informed as to the proposed site of evolution of the aquatic ape? Archaeology insists on East Central Africa, so what are the beaches of Kenya, Botswana etc like? Could this stretch of coast have supported the entire evolution of man, or is convergent evolution of aquaticism after migration a possibility?

If we use our brains to our full capacity, then how is it that autistic savants can do instant math, and other instant calculations, multiplying gigantic numbers, taking square roots, identifying the number of line intersections on a board full of scribbles, all instantly...

The fact that some people have photographic memories, and others (autistics) can do instant calculations, means simply that the rest of us aren't even using a fraction of our capacity. To say that 50% of our brain is unused is not the correct way of putting it. All our brain cells may be somewhat active at all times, but we still may not be using our potential. A supercomputer may have 100,000 processors, each of which drains 10W of power. But, if the processors are not working together and connected properly, the computer will still have the processing power of just one 10W processor, even though the computer drains 100,000 *10W of power.

Eric Fattah
BC, Canada

Just as our brain seems more powerful than it needs to be, so it is with other organs as well. Opthalmologists have found that the extrinsic eye muscles (recti & oblique muscles) are far stronger than they need to be in order to accomplish their purpose (by some estimates 10 times stronger than needed to move the eye rapidly). Unless, of course, they were once used to bend & shorten the length of the eyeball, as marine mammals do. Changing the shape of the eye requires far more muscle power than moving the eye.


Eric Fattah
BC, Canada

Aquatic Ape theory

Not sure if this has been mentioned, but another adaptation I have heard mentioned is that shape of the nose on humans compared to apes.

Apes have nostril openings that face forwards/slightly upwards and would collect water whilst swimming with the head forward.
http://www.ucsc.edu/oncampus/art/ape.155.gif

Whereas humans have nostrils that face backwards when swimming forwards.

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Also our nosethril openings now stand as a stronger candidate for an aquatic adaption. But it could also to not collect dust / sand blowing around on the savanna?
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Yeah well, then you would also see it on a primate like the baboon who also lives on the savannah.

Concerning the strength of the eye muscles, I would try to compare this phenomenon evenly to another primate, like the baboon (shared habitat?) or chimp (closest relative). If these are weaker by comparison, then we definitely have a strong voice for an aquatic adaptation of the eyes.
Have such kind of studies been made?

I'm surprised no one has commented on this thread in four years! Being a science guy, I’ve collected a lot of info about this theory over the ages. I will try to only post what has not already been mentioned.

--The most widely held theory, is that the distinctly human features are thus supposed to be adaptations to a savannah environment. In that case, we would expect to find at least some of these adaptations to be paralleled in other savannah mammals. But there is not a single instance of this, not even among species like baboons and vervets, which are descended from forest-dwelling ancestors. This awkward fact has not caused savannah theorists to abandon their hypothesis, but it leaves many problems unanswered.

--AAT points out that most of the "enigmatic" features of human physiology, though rare or even unique among land mammals, are common in aquatic ones. If we postulate that our earliest ancestors had found themselves living for a prolonged period in a flooded, semi-aquatic habitat, most of the unsolved problems become much easier to unravel. There is geological evidence to support this hypothesis, and nothing in the fossil record that is inconsistent with it.

--Two kinds of habitat are known to give rise to naked mammals - a subterranean one or a wet one. There is a naked Somalian mole rat that never ventures above ground. All other non-human mammals that have lost all or most of their fur are either swimmers like whales and dolphins and walruses and manatees, or wallowers like hippopotamuses and pigs and tapirs. The rhinoceros and the elephant, though found on land since Africa became drier, bear traces of a more watery past and seize every opportunity of wallowing in mud or water.

--It has been suggested that humans became hairless "to prevent overheating in the savannah.” But no other mammal has ever resorted to this strategy. A covering of hair acts as a defense against the heat of the sun: that is why even the desert- dwelling camel retains its fur. Another version is "to facilitate sweat-cooling.” But again, many species resort to sweat cooling quite effectively without needing to lose their hair. Furthermore, human hair is broadly aligned in such a way as to match fluid flow lines while swimming or sweating. There is no known reason why an ape should suffer more from overheating than the savannah baboon. And, especially for a savannah primate, there would be a high price to pay for hairlessness. Primate infants are carried around clinging to their mothers' fur; the females would be severely hampered in their foraging when that no longer became possible.

--One general conclusion seems undeniable from an overall survey of mammalian species: that while a coat of fur provides the best insulation for land mammals the best insulation in water is not fur, but a layer of fat.

CRITICISMS: Fur or hair is no great hindrance underwater. Fur seals, otters, beavers, and polar bears haven't lost theirs and they swim better than we do. Only some aquatic mammals have lost all or most of their hair, and they are almost invariably very large species weighing a ton or more, whose ancestors have been living in the water for tens of millions of years. The quality of having many small and numerous fat cells under the skin is not unique to humans among land animals. Rather it is shared with many species including hedgehogs, monkeys and badgers. In addition, the distribution of these fat cells in humans does not correspond with the distribution of fat cells in whales, seals or other aquatic mammals. Fat in aquatic mammals had evolved for use in streamlining and insulation (though not as insulating as blubber), and fat in humans does not function in this way nor to the same extent.

--Human beings are the only mammals in the world that habitually walk on two legs. Compared with running or walking on four legs it has many disadvantages. It is slower; it is relatively unstable; it is a skill that takes many years to learn, and it exposes vulnerable organs to attack. We have been doing it for five million years and in that time our bodies have been drastically remolded to make it easier, but it is still the direct cause of many discomforts and ailments such as back pains, varicose veins, hemorrhoids, hernias and problems in childbirth. It would have been far more difficult and laborious for our ape-like ancestors; only some powerful pressure could have induced them to adopt a way of walking for which they were initially so ill suited.

--One hypothesis used to be that they first developed big brains and began to make tools, and finally walked on their hind legs to free their hands for carrying weapons. But we now know that it was bipedalism that came first, before the big brain and tool making.

--However, if their habitat had become flooded, they would have been forced to walk on their hind legs whenever they came down to the ground in order to keep their heads above water. The only animal that has ever evolved a pelvis like ours, suitable for bipedalism, was the long-extinct Oreopithecus, known as the swamp ape.

--Today, two primates when on the ground stand and walk erect somewhat more readily than most other species. One, the proboscis monkey, lives in the mangrove swamps of Borneo. The other is the bonobo or pygmy chimpanzee; its habitat includes a large tract of seasonally flooded forest, which would have covered an even more extensive area before the African climate became drier.

--Both of these species enjoy the water. It is interesting that the bonobos often mate face-to-face as humans do; in our case, it is explained as a consequence of bipedalism. This mode of mating is another characteristic very rare among land animals, which we share with a wide range of aquatic mammals such as dolphins, beavers and sea otters. What we have in common with them is a mode of locomotion in which the spine and the hind limbs are in a straight line, and that affects the position of the sex organs.

--Voluntary breath control appears to be an aquatic adaptation because, apart from us, it is found only in aquatic mammals like seals and dolphins. When they decide how deep they are going to dive, they can estimate how much air they need to inhale.

--We have a different way of sweating from other mammals, using different skin glands. It is very wasteful of the body's essential resources of water and salt. It is therefore unlikely that we acquired it on the savannah, where water and salt are both in short supply.

--We weep tears of emotion, controlled by different nerves from the ones that cause our eyes to water in response to smoke or dust. No other land animal does this. There are marine birds, marine reptiles and marine mammals that shed water through their eyes, or through special nasal glands, when they have swallowed too much seawater. This process may also be triggered in them by an emotional excitement caused by feeding or fighting or frustration. Weeping animals, apart from us, include the walrus, the seal and the sea otter.

--We have millions of sebaceous glands which exude oil over head, face and torso, and in young adults often causes acne. The chimpanzee's sebaceous glands are described as "vestigial" whereas ours are described as "enormous.” Their purpose is obscure. In other animals, the only known function of sebum is that of waterproofing the skin or the fur.

And here's the rest of my archives.

--It is now generally agreed that the man/ape split occurred in Africa between 7 and 5 million years ago, during a period known as the fossil gap. Before it, there was an animal which was the common ancestor of human and African apes. After it, there emerged a creature smaller than us, but bearing the unmistakable hallmark of the first shift towards human status: it walked on two legs.

--The oldest pre-human fossils are called Australopithecus Afarensis because their bones were discovered in the afar triangle, and area of low-lying land near the Red Sea. About 7 million years ago, that area was flooded by the sea and became the Sea of Afar. Part of the ape population living there at the time would have found themselves living in a radically changed habitat. Some may have been marooned on offshore islands. Others may have lived in flooded forests, salt marshes, mangrove swamps, lagoons or on the shores of the new sea, and they would all have had to adapt or die. AAT suggests that some of them survived, and began to adapt to their watery environment. Much later, when the Sea of Afar became landlocked and finally evaporated their descendants returned to the mainland of Africa and began to migrate southwards, following the waterways of the Rift Valley upstream. There is nothing in the fossil record to invalidate this scenario, and much to sustain it. Lucy's bones were found at Afar lying among crocodile and turtle eggs and crab claws at the edge of a flood plain near what would then have been the coast of Africa.

--We now know that the change from the ape into Australopithecus took place in a short space of time, by evolutionary standards. Such rapid speciation is almost invariably a sign that one population of a species has become isolated by a geographical barrier such as a stretch of water.

--The Aquatic phase took place more than 5 million years ago. Since then, Homo has had five million years to re-adapt to terrestrial life. It is not surprising that the traces of aquatic adaptation have become partially obliterated and have gone unrecognized for so long. But the traces are still there as the table indicates.

--Human infants are born covered in [ame="http://en.wikipedia.org/wiki/Vernix_caseosa"]vernix caseosa[/ame], a waterproof coating also seen in newborn [ame="http://en.wikipedia.org/wiki/Common_seal"]common seals[/ame], and continue to draw oxygen through the [ame="http://en.wikipedia.org/wiki/Umbilical_cord"]umbilical cord[/ame] while underwater. Human infants naturally hold their breath and can (at least theoretically) swim from birth. Other land animals must be trained.

--Most animals which move to plains life tend to develop smaller brains, while aquatic animals tend to evolve larger ones, quite possibly because of access to omega-3. Omega-3 fatty acids also promote [ame="http://en.wikipedia.org/wiki/High_density_lipoprotein"]HDL cholesterol[/ame] and cardiovascular health in humans, while the [ame="http://en.wikipedia.org/wiki/Saturated_fat"]saturated fats[/ame] in [ame="http://en.wikipedia.org/wiki/Pork"]pork[/ame], [ame="http://en.wikipedia.org/wiki/Beef"]beef[/ame] and other land-based meats do the opposite. Yet for land-based carnivores the opposite is true and they have special digestive enzymes to neutralize the harmful effects of dietary cholesterol. It is noteworthy that many nutritionists find seafood to be the healthiest protein source for humans, whereas the meat of land-based mammals such as from beef or pork are the most harmful.

--Amongst primates, kidneys normally exhibiting lobulated, multipyramidal, medullas is a unique attribute of the human species. Although kidneys naturally multipyramidal in their medullary morphology are rare in terrestrial mammals, kidneys with lobulated medullas do occur in elephants, bears, rhinoceroses, bison, cattle, pigs, and the okapi. However, kidneys characterized with multipyramidal medullas are common in aquatic mammals and are nearly universal in marine mammals. To avoid the deleterious effects of saline water dehydration, marine mammals have adaptively thickened the medullas of their kidneys – which enhances their ability to concentrate excretory salts in the urine. However, the lobulation of the kidney’s medullary region in marine mammals appears to be an adaptation to expand the surface area between the medulla and the enveloping outer cortex in order to increase the volume of marine dietary induced hypertonic plasma that can be immediately processed for the excretion of excess salts and nitrogenous waste. A phylogenetic review of freshwater aquatic mammals suggest that most, if not all, non-marine aquatic mammals inherited the medullary pyramids of their kidneys from ancestors who originally inhabited, or frequented, marine environments. So this suggest that most, if not all, aquatic mammals exhibiting kidneys with lobulated medullas are either marine adapted – or are descended from marine antecedents. Additionally, a phylogenetic review of nonhuman terrestrial mammals possessing kidneys with multipyramidal medullas suggest that bears, elephants and possibly rhinoceroses, also, inherited their lobulated medullas from semi-aquatic marine ancestors. The fact that several terrestrial mammalian species of semi-aquatic marine ancestry exhibit kidneys with multipyramidal medullas, suggest that humans may have, also, inherited the lobulated medullas of their kidneys from coastal marine ancestors.

--Human facial structure is quite different from other apes, with thick eyebrow hair and downturned nostrils. The shape of the human nose, with nostrils running perpendicular to the rest of the face, prevents water from entering the nose while upright. Thick eyebrows allow water to flow from the top of the head away from the eyes upon surfacing, allowing for faster adjustment to vision through air. Human facial hair forces water to flow away from and around the nose and mouth to enable faster inhalation upon surfacing.

--In addition, The Savanna Hypothesis has yet to explain the pattern of hair that we do have, and why women and children have less body hair than men. On the first point, why should we have retained head hair if the purpose of a naked skin is to keep cool? On the side of aquatic ape theory, it may be noted that the top and the back of the head are the areas least in contact with water in the human pattern of swimming, and also the only areas covered with thick hair in both mature individuals and (some) infants. On the second point, it is possible to suggest an aquatic scenario in which mature males spent more time near the shore, while mothers with babies stayed in deeper water out of reach of land predators. By contrast, it is difficult for the temperature regulation hypothesis to accommodate a case where females and infants were more active than males, and therefore more in need of sweat-cooling, in the heat of the day.

Sorry for the long two posts, but my classes are boring me to death. Some of this information may be found at: http://www.primitivism.com/aquatic-ape.htm