To: All Msg #13, Nov0793 03:42PM Subject: Re: Request for Summary Aquatic Ape Theory Follo

Master Index Current Directory Index Go to SkepticTank Go to Human Rights activist Keith Henson Go to Scientology cult

Skeptic Tank!

From: Pat Dooley To: All Msg #13, Nov-07-93 03:42PM Subject: Re: Request for Summary - Aquatic Ape Theory Organization: Co-Cam Computer Group, Oz From: (Pat Dooley) Message-ID: <> Followup-To: Newsgroups:,,sci.anthropology The Aquatic Ape Theory ---------------------- This is a summary of Elaine Morgan's expositions with a few additions from other sources. For a proper introduction, please read her book, "The Scars of Evolution". Some useful evolutionary principles ----------------------------------- 1. Convergent Evolution: When two organisms occupy similar environments, they often evolve similar adaptations. For example, bats and two cave-living birds have evolved echo-location. 2. Non-disadvantageous intermediates: Evolution will never proceed from one form to a more advantageous form if the intermediate form is disadvantageous. 3. Dollo's Law: Evolution is irreversible. That means that if a particular adaptation appears , it is extremely unlikely that that adaptation, and that adaptation alone, will disappear. 4. The dirty slate of evolution: This principle simply states that evolution cannot design a new feature starting with a clean slate; it can only adapt existing features. For example, vertebrate eyes are wired back-to front, with the millions of nerves connecting the photo-receptors to the visual cortex running across the retina and exiting through the "blind-spot". If the vertebrate eye had been designed from a clean slate, the nerves would have been directly connected to the visual cortex. Octopii got it right, indicating that their eyes evolved independently of vertebrate eys. (Remember this example next time a myopic creationist tries to tell you how perfectly God made the human eye). 5. Evolution doesn't progress uniformly: The experts forgot this one as they described the evolution of man from the ape ancestor, based on very early ape fossils and quite recent Homo fossils. They assumed that bipedalism and brain size evolved together at a fairly uniform rate. Lucy proved that the evolution of bipedalism was virtually over before the rapid evolution of Homo's brain had even begun. One still sees popular stage-by-stage representations of the evolution of Homo sapiens showing an ape slowly growing more erect, with the head growing larger, the forehead more vertical, the skin getting progressively less hairy and paler. History of the Aquatic Ape Theory --------------------------------- The Aquatic Ape Theory (AAT) was initially proposed by Sir Alister Hardy and (shades of Darwin and Wallace), independently, by Max Westenhofer, a German professor who published a little-known book on human evolution in 1942 (bad timing!) that included a chapter on the aquatic hypothesis. The AAT was popularised by Elaine Morgan in three books: 1. The Descent of Woman 2. The Aquatic Ape 3. The Scars of Evolution The Aquatic Ape Theory (AAT) proposes that after separation from a common ape ancestor, the evolutionary line leading to Homo sapiens became partially adapted to an aquatic or semi- aquatic habitat before returning to a terrestrial environment. How aquatic are humans? ----------------------- Babies have a vestigial swimming instinct. They can be taught to swim before they can be taught to walk. They know instinctively not to breathe under water. Adults can swim long distances, even in cool water. For example, in 1987, Lynne Cox swam across the Bering Strait without wet-suit or layer of lanolin in 4 hours in water ranging from 3 to 7 degrees Celsius. In 1993, a South Australian helicopter crash survivor swam 10-15km to shore after spending two hours supporting the injured pilot. He claimed his extra weight helped him survive in the cool water. Humans dive well. Diving women in Japan and Korea work four hours per day diving up to 80' to collect shellfish and seaweed. The human record is 262' compared to observed depths of 150' for penguins and 300' for walruses. Duration underwater is as long as 3.5 minutes compared to 4.5 minutes for sea otters and 10 for walruses. During a dive, the human heart rate drops from 72 to 35 beats/minute compared to a drop from 95 to 20 in sea lions. Comparable figures for apes and other primates are not yet available. Humans have conscious control over their breathing, a useful adaptation for a swimming/diving mammal. Many human communities exploit marine environments without the aid of tools or technology (Australian aboriginals, pearl divers, coastal communities in SE Asia and Papua New Guinea). Humans seek out and enjoy sea food. Molluscs and crustaceans are particular favourites. AAT Features ------------ The AAT attempts to account for the following features that separate Homo sapiens from the other apes. 1.Bipedalism (i.e. walking upright on two legs without the assistance of a counterbalancing tail). The AAT claims that bipedalism evolved when environmental/climatic/ geological changes forced an isolated group of apes to start foraging in an aquatic environment. The move into the water would lead to the adoption of wading, followed by swimming and diving. Evidence from convergent evolution: Apes and other primates, because of their arboreal existence are already partially adapted for bipedalism. If a distant ape relative was forced into water, it would wade bipedally, whereas a quadruped would swim. We might note that the ancestors of all fully aquatic mammals were quadrupedal and observe that Proboscis monkeys, which have adopted a partially aquatic life in their recent evolutionary history, wade in shallow water and swim in deeper water. The Oreopithecus, an extinct ape that apparently lived in marshland, had undergone skeletal changes to its pelvis that suggest it was bipedal or a swimmer or both. Note that bipedalism has the advantage of facilitating swimming and diving. No purely terrestrial primate or mammal, let alone savannah mammal, has evolved 100% bipedalism. The probable reason is the principle of disadvantageous intermediates; the first nearly bipedal animal would totter along like a two year old. The AAT claims that the only environment that would facilitate bipedalism in a primate is aquatic. Fossil Evidence: There is a gap in the hominid fossil record from around 7 million years ago (mya) through to around 4 million years ago. The skeletons of Australopithecus afarensis, a likely hominid precursor of the Homo line, shows that bipedalism had fully evolved during that fossil gap. The evidence for bipedalism has also been preserved in fossilised footprints. The ecology of the fossil sites suggests a lush environment rather than the arid savannah. Lucy, the first nearly complete skeleton of an Australopithecus afarensis, had feet that were broader and larger than ours, (35% of leg length instead of 26%). Her gait was described by Roger Lewin as "not quite as bad as trying to walk on dry land wearing swimming flippers but in the same direction." Observations: Humans still suffer from the rapid evolution of bipedalism - back problems, inguinal hernia, varicose veins, blood pressure problems (complex biomechanical explanation omitted). Bipedalism is about as efficient as quadrupedalism for walking but less efficient when running. The evolution of bipedalism required major skeletal adjustments. According to Richard Leakey and Roger Lewin (who studiously ignore the AAT), "the evolutionary shift from quadrupedalism to bipedalism would have required an extensive remodelling of the ape's bone and muscle architecture and of the overall proportion in the lower half of the body. Mechanisms of gait are different, mechanics of balance are different, functions of major muscles are different. An entire functional complex had to be transformed for efficient bipedalism to be possible." cf. "Origins Reconsidered". 2. Hairlessness Desmond Morris wrote a book called "The Naked Ape" that drew attention to another feature that separates humans from our closest ape relatives (apparently the bonobo [pygmy chimpanzee] and chimpanzee). The AAT observes that hairlessness in mammals is most often associated with aquatic and semi-aquatic animals, usually combined with a layer of subcutaneous fat. Humans still retain hair on their heads, although this is stronger in females than males. Male humans tend to go bald, whereas females retain their hair. Moreover, female hair grows thicker and more strongly during pregnancy. The AAT suggests that head hair was retained as protection against solar radiation for an animal that waded and swam. It further suggests that female head hair was favoured to provide something for baby aquatic apes to hang onto. The reasons why an aquatic mammal would lose its fur are obvious: streamlining to enhance swimming and diving ability. Those aquatic mammals that have retained their fur, because they spend time on land in colder climates, have extensively modified it for the aquatic environment. The smaller ones have gone for oily fur, whereas the larger ones, like seals, have gone for a soft, dense inner coat capable of trapping tiny air bubbles, and an outer layer of glossy guard hair. Evidence from convergent evolution: The only bald mammal with no aquatic associations is the mole rat, which lives underground. The hairless or vestigially hairy mammals include the walrus, dugong, whale, dolphin, hippopotamus, tapir (marshland), pig (wallowers), elephant, and, surprise, surprise, Homo sapiens. (The elephant may have had a partially aquatic past. It is still a good swimmer and wader that gravitates towards water.) Fossil evidence: None. Hair doesn't fossilise, so we have no way of knowing whether hair loss was recent, a long time ago, or gradual over the last 10 million years (say). Observations: Hairlessness has often been claimed, along with sweating, as an adaptation for life on the African savannah. However, night time on the savannah is cool (11 degrees Celsius) and damp during the rainy season. It is also difficult to reconcile subcutaneous fat, an adaptation to retain body heat, with a cooling mechanism. Fur provides good protection against solar radiation and cold savannah nights. Loss thereof appears maladaptive for a woodland or savannah ape. 3. Subcutaneous fat Humans are very fat by terrestrial mammalian standards and most of it is stored just under the skin. In a new-born baby, it comprises 16% of body weight compared to 3% in a baboon. It comprises 27% of the body weight of a 16 year old girl. If it falls below 22% she will either not begin or will cease menstruation, even if she lost the fat through an athletic regime rather than ill-health or malnutrition. (Big clue: anything affecting reproduction is evolutionally significant.) The fat is stored under the skin, rather than in internal deposits, so gross obesity is a uniquely human problem; there is nothing, least of all the flexible skin, to constrain growth. A survey of 191 mammal species showed humans have 10 times as many adipocytes as would be expected in a mammal of similar mass. Since, God knows, we don't need this fat now, it is reasonable to conclude that it evolved to meet some past environmental need and that we were probably even fatter in the past. The AAT claims that a subcutaneous fat layer is an aquatic feature that provides buoyancy and insulation. It is maladaptive on land because it impedes the healing of flesh wounds and it costs energy to grow and carry around. Evidence from convergent evolution: A subcutaneous fat layer (blubber) is common in aquatic and wallowing mammals, where it provides insulation and buoyancy. It was watching a seal being dissected that first suggested the AAT to Sir Alister Hardy, back in 1930. 4. Sweating Mammals have two types of moisture producing glands on their skins. Acropine glands are associated with hair follicles and initially evolved for scent production. Eccrine glands are normally found on the pads of paws and exude a small amount of moisture to improve grip. Apes have eccrine glands on their palms and soles that exude moisture to improve their grip in an arboreal environment. Humans still have vestiges of this response; the sweaty palms, associated today with emotional tension, have more to do with an arboreal ape's preparation for flight than with human heat regulation. Apes have almost as many acropine glands but they don't appear to do be used for anything except scent production in the armpits and groin. Mammals that do sweat use acropine glands. The amount of moisture exuded is limited to the amount that will evaporate, maximising the cooling effect while minimising water and electrolyte loss. Man has lost almost all his acropine glands. The few that are left are restricted to the groin and armpits, where, as in apes, they do a poor job of producing "attractive" scents. Humans have co-opted the eccrine glands for sweating. That adaptation has not yet been perfected. Sweating is slow to start up, and is wasteful of water and salt. According to William Montagna, author of "Advanced Views in Primate Biology", "sweating is an enigma that amounts to a major biological blunder: it depletes the body not only of water but also of sodium and other essential eloctrolytes that are carried off with the water". The AAT claims that, along with most aquatic animals, man lost most of his acropine glands because scents are ineffective in water. The eccrine glands were co-opted for salt excretion, a problem that air-breathing marine animals solve in a variety of ways. When proto-hominids moved back to a terrestrial existence and had to cope with severe over heating problems, the usual evolutionary solution is sweating. Unfortunately, the acropine glands were no longer available, so the eccrine glands were co-opted Observation: A non-aquatic theory of human evolution has to explain why the usual terrestrial mammalian thermal regulation system of fur, panting, and (optional) acropine sweating was replaced by hairlessness, subcutaneous fat and profuse, salty eccrine sweating. No other terrestrial mammal, let alone primate, has evolved such a system. Even if this system is accepted as an efficient cooling system, a purely terrestrial explanation of its evolution probably violates the principle of non-disadvantageous intermediates. The non-aquatic version of the evolution of sweating also ignores the principle of the dirty slate. If sweating had steadily evolved for heat regulation, it would have used acropine glands, as it did in baboons. Aquatic and semi-aquatic mammals have often evolved hairlessness and blubber. The AAT says these evolved first and sweating later. 5. Breathing Humans differ from the other apes in that they have conscious control over their breathing. The descended larynx, a feature shared with dugongs and sea lions is unknown amongst terrestrial mammals. The disadvantage of this arrangement is that the passages to the lungs and the stomach are no longer separated. Humans cannot drink and breathe simultaneously (although new born humans can; the descent occurs after a few months). Swallowing is made much more complicated by the need to ensure that food and drink do not accidentally "go down the wrong way". The AAT claims that the descended larynx assisted the AA in taking in lots of air quickly, before diving. It also claims that conscious control over breathing is a necessary adaptation for an aquatic mammal. It further notes that these evolutionary changes pre-adapted Homo for speech. 6. Minor items Vestigial webbing still appears in around 6% of the population. The flap of skin between thumb and forefinger is absent in other apes. Humans under emotional stress shed salt tears. Oddly, this event is often accompanied by a "lump in the throat", an involuntary muscular contraction that prevents anything entering the stomach. These unexplained features may be vestiges of a marine past. Human sexual behaviour is different from other apes. Oestrus, the usual mammalian method of regulating sex by signalling when the female has ovulated, has disapeared. The sexual equipment has been extensively modified, with the rotation of the pelvis bringing the vaginal opening forward and the penis growing longer to follow it around. At some point, it lost the race; and the male switched to face-to-face copulation as the standard method. In contrast to apes, the vagina is retracted into the body and covered by thick folds of skin, a common aquatic adaptation. Location and timing ------------------- The AAT notes that there is still a fossil gap from 7-9 mya through to 4-3.5 mya. It observes that hominid fossils have been found in the Rift valley, a massive fault line running down East Africa. It suggests that the aquatic ape moved down from the inland Sea of Afar when it became too salty to sustain life. Paul Mohr, a geologist, summed up the geological evidence about the Sea of Afar as follows "by the late Miocene (7 mya), a marine basin had become established over Northern Afar". It is now a massive depression with deep salt deposits; the Dead Sea is going the same way. The Danakil Alps are at the Eastern end of the salt plain and comprised an island in the Sea of Afar. Note that the Sea of Afar was formed at about the time when DNA dating tells us that man split off from the apes. Leon P. Lalumiere of the US Naval Research Laboratory suggested Danakil Island as a place where a group of Miocene apes might have got marooned. He notes "that geographic speciation is the almost exclusive mode of speciation amongst animals". Small populations on an island can undergo rapid evolution, especially when the environment is changing rapidly. This geological evidence provides a location where a group of miocene apes could have been forced into foraging in water in isolation from the rest of the original species. The subsequent evaporation of the Sea of Afar would have opened up land bridges back into mainland Africa and the increased salinity would have slowly wiped out the food supply of the aquatically adapted apes. We are more different from chimpanzees and gorillas than they are from each other, yet the DNA evidence says gorillas branched off earlier than the chimpanzee/human split. A period of island evolution in a rapidly changing environment would account for this anomaly. Memo to anti-AAT paleoanthropologists - the Danakil Alps might still be worth a look. According to one E-mail AAT objector, a dozen or more Miocene apes went extinct. Maybe that bears on the next piece of evidence for island evolution. The Baboon marker gene is a viral gene sequence closely related to the RNA genomes of a retrovirus, referred to as "Type C", that is endogenous to Baboons and harmless to them. Of 23 African ape and monkey species tested, 100% possessed the Baboon marker gene. It apparently evolved to provide protection against the Baboon retrovirus, when, like AIDS, it crossed the species boundary. It must have devastated primate populations and wiped out any that couldn't evolve the Baboon marker gene quickly enough. The wide range of species infected suggest that the virus was air-borne. Viruses evolve, so that a virulent strain cam emerge and then fade away again. The odds against the Baboon marker viral gene sequence not deriving from the Baboon Type C retrovirus are astronomical. The same DNA sequence independently evolving 23 times? And it did evolve within the last 10 million years or so; otherwise, Asian primates would have the same sequence. The Baboon marker gene was absent from the 17 non-African primates tested, and Homo sapiens. The most reasonable conclusion to draw is that after our ancestors split off from chimpanzee's ancestors, they spent a period of evolution outside of Africa, thus avoiding the Baboon Type C retrovirus when it was attacking other primate species. One location for that period might be the Danakil Island. Answers to common objections ---------------------------- 1. The experts think the AAT is a load of bunkum. Well, any good crackpot theorist can quote the example of Wegener and his wild theory of continental drift. The opponents can always quote Velikovsky, but his theories were soon refuted once scientists and historians bothered to examine them. But the experts have not been able to come up with a theory of human evolution that satisfies Occam's razor as well as the AAT, let alone refutes the AAT. Often, they violate the evolutionary principles I noted at the beginning of this post. At least a few experts have acknowledged that the AAT is worthy of serious consideration. 2. Some people are afraid of water Some are afraid of heights, but it doesn't mean our distant ape ancestors weren't arboreal. 3. The AAT describes the period of evolution leading up to Lucy, but she was still adapted for arboreal life. In "Origins Reconsidered" it is noted that Australopithecus afarensis (A.a.) was still partially adapted for an arboreal life. That does not disqualify the AAT. Firstly, previous adaptations do not disappear very quickly unless they are maladaptive in a new environment. The curved phalanges (fingers) and relatively long arms of A.a. may have suited an aquatic life style even though they were evolved for an arboreal existence. The long, curved phalanges (toes) of A.a., with webbing, may have been natural flippers. Secondly, the AAT may have evolved in coastal swamps, as the proboscis monkey is currently doing. When it descends from a tree, the proboscis monkey has two choices: swim or wade and it can do both with reasonable facility. They have been filmed walking bipedally on dry land. 4. Humans have to be taught to swim and dive By the time it got to birds and mammals, evolution had discovered that it was often better to invest in learning ability rather than hard-wired behaviour. Lots of animal behaviour, such as hunting, killing, foraging, copulating, flying and swimming, has to be taught or learnt by observation of adult behaviour. Be that as it may, very young human babies seem to have vestigial swimming instincts, despite 4 million years of post aquatic evolution. 5. But we are no longer aquatic This objection usually comes from people who have erected the straw-man of a seal-like ape, fully evolved for an ocean life. That misrepresents the AAT. Learn about the proboscis monkey, project its evolution for another million years or so, and then pull the bathplug on it. 6. The sharks/crocodiles/box jelly fish would have eaten them. Plenty of other mammal and bird species have made the transition to an aquatic existence and survived the threats of marine predators. Sharks kill far fewer people than lightening, despite the greater propensity for humans to swim in the ocean compared to staying outdoors during a thunderstorm. There is no environment, terrestrial or otherwise, which is free from predators, and any successful species has figured out how to avoid extinction by predation. 7. Other primates copulate face to face Bonobos, according to one E-mail AAT objector, also copulate face to face. So do Orang Utans, although the male's technique would see him up on rape charges if he was human. So what. This is an example of evolution working from a dirty slate. AAT predictions --------------- The Aquatic Ape theory predicts (according to me) that: 1. Bonobos, chimpanzees, gorillas and savannah primates, such as baboons, will prove inferior waders, swimmers and divers to Homo sapiens. 2. When these other primates are immersed in cold water, they will lose body heat much more rapidly than Homo sapiens. 3. The diving reflex in the other primates will be much less pronounced than in humans, if it is present at all. 4. At the annual Apes' buffet luncheon, Homo sapiens will eat all the sea food while the other apes will go for the salads and fruit. 5. Fossils showing the evolution of bipedalism will be found in those parts of NE Africa that were isolated from mainland Africa between 9 and 4 million years ago. 6. Please E-mail any further predictions to me and I'll include them in an AAT prediction list. ----------------------------------------------------- Pat Dooley trying to summarise the Aquatic Ape Theory


E-Mail Fredric L. Rice / The Skeptic Tank