I don't think that is entirely right, since the history of human evolution is still very slippery to scientists. They have constructed our theoretical “evolution tree” with the fossils that have been found so far, and there are many “evolutionary leaps” or jumps in evolution with hundreds of thousands of years intervals since 2 million years ago and the farther you go in time, the more blurry our ancestor become, and the bigger the intervals between the evolution jumps. These evolutionary leaps are most likely caused by sudden changes in the genes of a given species. But in either case, all we have is theories as to why certain characteristics of the species changed; we know it was natural selection, but we speculate about environment and behavior. In any of these evolutionary “intervals” it is perfectly feasible that an ancestor that lived mainly in the sea shores lost the fur that is characteristic of apes; and developed many characteristics of aquatic mammals and then they went back to land. This could have perfectly happened in a “1 million year period”, so it gives much space for speculation. And this could have happened many times in our evolution, going back and forth from land to shore. So this could have also been a gradual change in our genetics. Around 5 million years ago, we share a common ancestor with today’s big apes and chimpanzees, and they haven’t lost their fur yet and don’t share the same semi-aquatic characteristics of the homo sapiens. About the picture of the monkeys: http://www.bloggerspoint.com/wp-content/uploads/2010/12/Monkeys-in-Japan-swim.jpg They started swimming in those hot springs since 1963; they found that this water protects them from cold, so now they go there every year. Normally monkeys are afraid of water, but under given circumstances they can adapt easily to a watery lifestyle. Also we have to consider that even in “climate change” periods when food supply was affected in land; there was still a lot of food in the shores.
If the only proposal you are willing to discuss under the heading of Aquatic Ape is one incorporating every single claimed result or consequence of an aquatic stage in hominid evolution, swallowed whole or dismissed as a unit, then we need a new name for what I would rather discuss. I see only dubious and unlikely benefits of hairlessness in an early stage aquatic ape, for example - any more than in fur seals, otters, polar bears, etc. The heat adaptation postulated by people like Bernd Heinrich seems more likely, to me, and that would have been fairly late in our development. My central observation here has been that the people dismissing an aquatic phase as key to some of the more unusual human evolutionary modifications have been using very poor arguments and accepting borderline absurdities in their own preferred just so stories. In particular, the key and central feature of bipedal locomotion seems to have generated a lot of bad evolutionary reasoning and downright silly proposals, while the intuitively reasonable notion of a wade/swim foraging ape finding bipedal locomotion incrementally useful and incrementally easy in water remains unrebuked.
Iceaura: Perhaps you should start a new thread describing your views. This thread relates to the Aquatic Ape Theory, which seems to have been discredited by mainstream anthropologists. It is not very productive to argue about the Aquatic Ape Theory without referring to a large amount of data on the subject at various Web Sites & in books on anthropology. When I first encountered this thread, my memory told me that the Aquatic Ape theory had been discarded by the mainstream, but I remembered nothing relating to the controversy. Before posting, I searched the Web & read some articles, both pro & con on the subject. The con articles seemed convincing to me. It does not seem productive to copy & paste thousands of words from various Web Sites. Those really interested in the subject should do some research. I am bowing out of this thread.
I don't think there is a single, unitary, all-inclusive Theory of the the kind. Certainly the arguments for it are not the thing itself - whether or not modern hairlessness stems from an aquatic stage in hominid evolution, for example, is not centrally and immovably part of the hypothesis of the stage having existed. It's a proposal, with some interesting ramifications and possibilities. The proposal is that hominids went through an evolutionary period of adjustment to aquatic or amphibious life of some kind. And my point was that mainstream anthropologists have proposed a good many far sillier and less physically supported notions, for things like hairlessness and bipedalism and opposable thumbs and the strange breathing or vocalizing structures of the human throat.
Modern Humans underwater: • All mammals have a diving reflex; but ours is specially developed, and it even slows down the heart rate 10-25% when our face is underwater. • Profesional divers can dive down to 30 meters underwater with 1 gulp of air; and the record of breath holding is 20 minutes underwater. o Then there is the blood shift that occurs only during very deep dives. When this happens, organ and circulatory walls allow plasma/water to pass freely throughout the thoracic cavity, so its pressure stays constant and the organs aren't crushed. In this stage, the lungs alveoli fill up with blood plasma, which is reabsorbed when the animal leaves the pressurized environment. This stage of the diving reflex has been observed in humans (such as world champion freediver Martin Štěpánek during extremely deep (over 90 metres or 300 ft) freedives. Habitat feasibility: o One thing is for sure, human beings (especially in groups) require being near an abundant water source for survival. o Biologically speaking, the habitat for humans was perfect near the shore. • The Australopithecus sediba (an adult and a child) was found inside what in his time was a 50 meter deep lake. And even his name “sediba” (which means natural spring, fountain or wellspring in Sotho) indicates their aquatic lifestyle. • It seems to me that the AAT was never truly considered in the mainstream paleontology, is perfectly plausible that our ancestor were merely more aquatic than our ape cousins. Not as in a complete “aquatic mammal”, but as a semi-aquatic one. This seems to be a more accepted theory in general: Waterside Hypotheses of Human Evolution: Assert that wading, swimming and diving for food have acted as an agency of selection in the evolution of human beings more than it has in the evolution of our ape cousins both before (and hence causing) the split between these lineages and after. It notes that even very slight levels of selection can still result in profound and rapid phenotypic changes. And how about Aquarboreal apes? - a combination of fossil (including the newly discovered Orrorin, Ardipithecus and Kenyanthropus hominids) and comparative data now provides evidence showing that: (1) the earliest hominids waded and climbed in swampy or coastal forests in Africa–Arabia and fed partly on hard-shelled fruits and molluscs; (2) their australopith descendants in Africa had a comparable locomotion but generally preferred a diet including wetland plants; and (3) the Homo descendants migrated to or remained near the Indian Ocean coasts, lost most climbing abilities, and exploited waterside resources. - New evidence confirms the idea that human ancestors were not savannah-dwellers at all, but instead became bipedal in swampy forests, and evolved during the Ice Ages into coastal omnivores along the Indian Ocean Human evolution is very theoretical due to the lack of consistent evidence, and it is not yet complete. PS: editted cause I miss-read the part of the first article, I read 30 minutes when it says 30 meters; thanks to Dywyddyr for the skepticism and adoucette for reading the article and pointing the flaw of my post.
Well I got it from here: http://news.bbc.co.uk/2/hi/science/nature/211473.stm But Sorry I read it wrong, It says 30 meters underwater. But here: http://news.discovery.com/human/breath-holding-human.html It says the record is almost 20 minutes so :shrug:. It is still a lot.
It says 30 meters not 30 minutes. It says they can hold their breath for more than 5 minutes. Like I posted, the record is 11 min 35 seconds. No one will ever make 30 minutes.
Sorry I miss-read that part, but the record is almost 20 minutes (see post above), and it is still far greater than any other non-aquatic-mammal.
Actually if you read that they discuss pre-breathing with pure O2. I believe that I'm correct that the unassisted record for what is known as Static Apnea is still 11 minutes 35 seconds. http://www.aidainternational.org/competitive/worlds-records Arthur
Still 11 minutes is friggin amazing. I could go to the store, buy milk and bread, and come back in less time.
Yes it is! I did a little research to check if this time is still considerable for this post; and it actually is very much so: Capability of mammals to hold their breath underwater: Human: 1-2 minutes (dynamic) and 8-10 minutes (static) Marine mammals: Polar bear (semi-aquatic): 1-2 minutes Aquatic mammals: Sea otter: 2-5 minutes Manatee: 3-5 minutes Killer whale: 5-15 minutes Dolphins: 8-15 minutes Sea lion: 8-20 minutes Sperm whale: 90-120 minutes * edit to remove duplicated text
The orca is a dolphin, merely the largest species. The sperm whale, technically, is a member of the cetacean suborder Odontoceti or "toothed whales," which makes it an offshoot of the dolphins. The other suborder is Mysticeti or "baleen whales," the largest animals that ever lived. I would be interested to learn how long they can hold their breath. In all of the cetaceans, the brain hemispheres take turns sleeping so the animal can return to the surface for breathing.
Someone claimed that the find of Ardipithecus refuted the aquatic ape suggestion. I would say it may confirm a suspicion that I don't remember who suggested (it wasn't Morgan), which is a potential relationship between the homo lineage and Oreopithecus. I have been very doubtful as to such a connection, but I find it very intriguing that Oreop. (9-7mya) and Ardip. (4.4mya) share a very similar grabbing 'thumb-like' big toe, which seems to have disappeared in the australopithecines (3.6-2.4mya) and homo (2.4-0mya). This also makes it interesting to reconsider the European Dryopithecus (12-9mya) as an ancestor to both Gorilla, Pan (chimp, bonobo) and Homo. Both because Oreop., which lived on a Mediterrenean archipelago including current Sardinia and Toscany, have the same big-toe, but also because pelvic studies suggest it was bipedal, as was Ardip. and later Australop. and Homo. On top of that, the charcoal layers in which Orepop. has been found (in large numbers, even) illustrate that it lived in wetlands (it has been dubbed 'the swamp ape'), which makes it interesting to consider as perhaps the first 'aquatic ape' of human evolution. Something that further supports this relationship, is that both Oreop. and its potential ancestor Dryop. have the iconic eyebrow bones, which all suggested human ancestors from Ardip. and all the way to Neanderthals have, and which Gorilla and Pan also have till this day, but which great apes in Africa simultaneous with Dryop. and Oreop. is missing. In such a scenario, human evolution (and the aquatic ape) would be as follows: A descendant of Proconsul, Dryopithecus, migrates out of Africa ca. 12mya in a warm period with tropical jungle expanding far into Eurasia. Some Dryop. evolve into modern Orangutan in East Asia, others evolve in Southern Europe. As colder climate sets in, the tropical jungle moves southward again and three descendants to Dryop. (Gorilla, Pan and Homo), evolve three-way and migrate back into Africa (possibly along the Iberian, this Mediterrenean archipelago and the Levant, one lineage each way). Two (Gorilla, Pan) stays in the jungles to this day, whereas the third (Homo) via the Mediterrenean archipelago evolve into a coastal form with Orepithecus, which then later evolve into Ardip., Australop. and Homo. In this scenario, humans have been aquatic apes for nine million years, with Orepithecus being the first non-common ancestor for humans and chimps, but only to humans. There are three problems with an Oreopithecus link, though (and plenty other, I'm sure). 1) Geographical: For both Gorilla, Pan and Homo to have migrated from Southern Europe back into Africa in the suggested time-frame would force a migration through the Sahara region. Today, this is the largest desert in the world, almost totally bereft of life and not very likely for an aquatic ape migration into East Africa. One could counter-argue, that Sahara has not always been a dry void, as even in historic times, rock paintings from human cultures show elephants, giraffes, etc. in the middle of a now dry desert. It could be interesting to determine the paleogeograpical characteristics of the Saharan region in the suggested time frame (circa 7mya), in view of this potential ape migration. If Sahara was indeed lush, green and perhaps wet in late miocene, one might find proto-human fossils along old river beds and lake shores with exposed layers from the suggested time frame. In this context, the species Sahelanthropus (7mya, the 'Toumaï' fossil) becomes interesting, being found in Tchad out in Sahara on a then lake shore. Then Sahel. might be a link between Oreop. and Ardip., also because Sahel. has the high eye brow bone. (Unfortunately, Sahel. was found with only scull fragments, so nothing can be concluded about potential bipedalism via the pelvis.) 2) Political-social: Considering a Southern European spawn of humanity would probably be a big camel to swallow for the academic community, considering the 19th century fight to get arrogant European scientists to even consider that humanity came from outside their own continent (another milestone by mr. Darwin). This one I'm personally very concerned about, even though I do see potential in the above perspective. 3) The molecular clock technique: Using this technique in its current form suggests, that the human-chimp divergence happened as late as 5-7mya, excluding both Oreop. and perhaps Sahel. as human ancestors (without being chimp ancestors). Or though some has suggested, that this method can be very inaccurate, as it only proposes values for how often random mutations occur, which may be impossible to predict. One review of the technique (White et al, 2009) suggests that the point of divergence can be anything from 5mya to 13 mya, making the above possible (or though most repeated experiments with the molecular clock technique conclude values similar to the former). Either way, the above can only be supported by finding proto-human fossils in the Sahara, should they exist. Otherwise, the whole thing is a wild goose chase. Incidentally, human freedivers are much deeper than 30 meters. There are diverse categories within that activity, which have become a competitive sport, and the current world depth records ranges from 101 meters (unassisted plunge without the use of fins) down to 214 meters (allowing assisted descend and ascend, usually via a weighted sled). The mentioned 20 minute static breathhold, however, was done on pure oxygen (similar to David blaine on Oprah, this freedivers internally consider 'cheating'), whereas the current world record on natural air is 11'35, as mentioned. Considering this surprising aquatic potential for modern Homo Sapiens Sapiens, the aquatic ape hypothesis does deserve some serious scrutiny, which I too agree that anthropological circuits so far has failed to provide it.
Please Register or Log in to view the hidden image! Hmm...this thread floated back up again... Apropos of nothing...since I'm skinny now, I can't do a deadfloat. I sink.
Possibly supporting the theory of the Aquatic Ape, the Fuegians of Teirra Del Fuego, as described by Darwin and others, were a tribe of people who were just as at home in the fridged seas as they were on land. Wearing next to nothing, they were seemingly impervious to cold although they were fond of keeping fires burning everywhere. They had vision superior to the best sailors and thought nothing of jumping off a ship and swimming miles back to land in the middle of the night. As it would happen, they died out thanks to white man incursion on their land and allegedly, white man diseases. Ref: enewsbuilder.net/tusker/e_article001520586.cfm?x=bg0V4r1,b4WlfP14,w
There have been several articles and TV shows about Ardi. They say that the single prehensile toe identifies the species as a transition from arboreal to ground-dwelling. Ardi could climb trees to evade danger, but not as nimbly as a chimpanzee. But a chimp cannot walk bipedally for long distances the way Ardi could. This left their hands free so a few individuals could walk a considerable distance and carry back an armload of food, and also so the females could carry their babies on a migration.
