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
