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Aquatic Ape Hypothesis

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Laura:

I've just recently read "Scars of Evolution" by Elaine Morgen and I have to say that it is a compelling read.  It's about the "Aquatic Ape Hypothesis".  I highly recommend it because it touches on a lot of topics that we discuss on the forum including polyvagal theory and the paleodiet.  Here's what Wikipedia has to say about it:


--- Quote ---The aquatic ape hypothesis (AAH) is an alternative explanation of some characteristics of human evolution which hypothesizes that the common ancestors of modern humans spent a period of time adapting to life in a partially-aquatic environment. The hypothesis is based on differences between humans and other great apes, and apparent similarities between humans and some aquatic mammals. First proposed in 1942 and expanded in 1960, its greatest proponent has been the writer Elaine Morgan, who has spent more than forty years discussing the AAH.

While it is uncontroversial that both H. neanderthalensis and early H. sapiens were better suited to aquatic environments than other great apes,[1][2] and there have been conjectures suggesting protohumans underwent some adaptations due to interaction with water[3] the sort of radical specialization posited by the AAH has not been accepted within the scientific community as a valid explanation for human divergence from related primates. It has been criticized for possessing a variety of theoretical problems, for lacking evidentiary support, and for there being alternative explanations for many of the observations suggested to support the hypothesis. Morgan has also suggested that her status as an academic outsider has hindered acceptance of the hypothesis.

History

In a 1942 book, the German pathologist Max Westenhöfer published the idea of humans evolving in proximity to water with the statement "The postulation of an aquatic mode of life during an early stage of human evolution is a tenable hypothesis, for which further inquiry may produce additional supporting evidence."[4]

In 1930 marine biologist Alister Hardy hypothesized that humans may have had ancestors more aquatic than previously imagined. Because it was outside his field and he was aware of the controversy it would cause, Hardy delayed reporting his hypothesis. After he had become a respected academic, Hardy finally voiced his thoughts in a speech to the British Sub-Aqua Club in Brighton on 5 March 1960, not expecting any attention, but it was reported in a national newspaper. This generated immediate controversy in the field of paleoanthropology. Consequently Hardy published the hypothesis in an article in New Scientist on 17 March 1960. He defined his idea:

    My thesis is that a branch of this primitive ape-stock was forced by competition from life in the trees to feed on the sea-shores and to hunt for food, shell fish, sea-urchins etc., in the shallow waters off the coast. I suppose that they were forced into the water just as we have seen happen in so many other groups of terrestrial animals. I am imagining this happening in the warmer parts of the world, in the tropical seas where Man could stand being in the water for relatively long periods, that is, several hours at a stretch.[5]

The idea received some interest after the article was published,[6] but was generally ignored by the scientific community thereafter. In 1967, the hypothesis was briefly mentioned in The Naked Ape, a book by Desmond Morris in which can be found the first use of the term "aquatic ape".[7] Writer Elaine Morgan read about the idea in Morris' book and was struck by its potential explanatory power, becoming its main promoter and publishing six books over the next 40 years.[8] The context of initial presentations of the idea (a popular work and a political text) prevented the AAH from garnering serious interest or an exploration of its scientific merit.[9]

Despite maintaining some popular and scientific interest over several decades, the aquatic ape hypothesis has not been accepted by a large majority of researchers within the field of paleoanthropology.[10] A small but active number of promoters working outside of mainstream paleoanthropology, non-anthropologists and the occasional professional still cite and bring attention to the AAH but it has never been completely discredited to its adherents nor fully explored by researchers.[9]
The hypothesis

The AAH suggests that many of the features that distinguish humans from their nearest evolutionary relatives can be explained through a period of aquatic adaptation in which protohumans spent time wading, swimming and feeding on the shores of fresh, saline or brackish waters (though there has been disagreement and modification of the theory regarding the salinity of the purported watery environment[11][12][13]) and suggests comparisons with other aquatic or semiaquatic species with similar characteristics. Some observations include:

    * Bipedalism out of water causes considerable problems for the back, knees and organs, while water would support the joints and torso and permit breathing[14][15]
    * Humans are relatively hairless compared to great apes, similar to the hairlessness of land-dwelling rhinoceros and elephant which both have aquatic ancestors;[16] what body hair humans do have also follows water flow-lines[17]
    * Increased subcutaneous fat for insulation, especially in human infants[5]
    * A descended larynx[17][18]
    * A hooded nose, muscular nostril aperture control and the philtrum preventing water from entering the nostrils[17]
    * Extensive coverage of the skin by sebaceous glands[19]
    * The requirement of the human brain for certain nutrients including iodine[20] and some essential fatty acids[21] which are most easily found and absorbed in seafood[22]
    * Voluntary breath control which allows diving and swimming,[14][23] and a more streamlined shape compared to other apes[17]
    * The mammalian diving reflex which occurs when the head is immersed in cold water[24]
    * Vestigial webbing between the fingers[25]
    * The waxy coating found on newborns[17]
    * Certain morphological adaptations within the kidney[26]

The timelines hypothesized for a period of adjusting to aquatic living vary from the Miocene about 6 million years ago,[5] to nearly 2 million years ago in the late Pliocene or early Pleistocene.[27][28] It is also theorized that the semi-aquatic phase occurred when protohumans migrated along the southern Asian coastline during a previous ice age when sea levels were considerably lower; this is also proffered as a reason why human fossils are not found in aquatic habitats, as those regions were inundated when the polar ice caps melted.[29]

Review of the individual claims used as evidence for the AAH generally does not support the hypothesis overall, and most of these traits have an explanation within conventional theories of human evolution.[9] Other authors have suggested that wading and other interactions with watery environments may have provided a less extreme but still present role in human evolution.[3]
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I'm not including the criticisms because they are basically of the usual corrupted science kind: demanding more proof of something they don't "believe" in than they demand of what they DO believe in!

Kniall:

--- Quote ---My thesis is that a branch of this primitive ape-stock was forced by competition from life in the trees to feed on the sea-shores and to hunt for food, shell fish, sea-urchins etc., in the shallow waters off the coast. I suppose that they were forced into the water just as we have seen happen in so many other groups of terrestrial animals. I am imagining this happening in the warmer parts of the world, in the tropical seas where Man could stand being in the water for relatively long periods, that is, several hours at a stretch.[5]
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I watched Super Comet: After The Impact last night, which posits that survivors of cataclysmic events naturally be drawn to coastlines because oceans would retain relatively milder temperatures than the extreme cold (from the resulting ice age) in the interiors of continents. So it could well be that profound and sudden environmental changes forced such an adaptation.

Psyche:
Perhaps the Von Economo cells in the brain are also related to the Aquatic Ape Hypothesis:


--- Quote ---Session 30 January 2010

(Psyche) I have a question. When we were discussing with I**** some type of cells that are located mainly in the frontal lobe of the brain, it seems that nobody knows what they are for. They are called spindle cells or "von Economo neurons" if I remember the name correctly. What are their function?

A: Consciousness orientation.

Q: (Ailén) Hmm.

(Andromeda) So I guess having a lot of those would be good?

(Burma Jones) So, is that like a registration bin for consciousness to figure out how to keep itself...

A: Energy directors.

Q: (Joe) Can you get more of them?

A: You may.

Q: (Joe) I wonder if those cells have anything to do with the third eye, like when you do the breathing and you look up...

A: Close, more like a "homing device".

Q: (Joe) A homing device for aliens?

A: Wave reader. {Cs refer to souled humans as “Wave Reading Consciousness Units.}

Q: (Ailén) I**** was saying that they're huge cells. Right? (Psyche) Yeah. She was wondering if they could be related to psychopathy, like the lack of those cells...

A: Oh yes.

Q: (Andromeda) Hmm...

(Ailén) She said there were some studies about schizophrenics not having so many of them also.

(Psyche) They have been studied in whales too.
--- End quote ---

More info on spindle cells or Von Economo cells here:

http://cassiopaea.org/forum/index.php/topic,15927.msg133918.html#msg133918


--- Quote ---Spindle neurons, also called von Economo neurons (VENs), are a specific class of neurons that participate in signal transmission in the nervous system, and are characterized by a large spindle-shaped soma, gradually tapering into a single apical axon in one direction, with only a single dendrite facing opposite. Whereas other types of neurons tend to have many dendrites, the polar shaped morphology of spindle neurons is unique. They are found in two very restricted regions in the brains of hominids  - the family of species comprising humans and other great apes. Spindle cells are also found in the brains of the humpback whales, fin whales, killer whales and sperm whales [1][2], bottlenose dolphin, Risso’s dolphin, beluga whales[3]  and in the brains of African and Asian elephants.[4]  The name von Economo neuron comes from their discoverer, Constantin von Economo (1876-1931).

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SethianSeth:
That book had been on my list after seeing her wonderful lecture on Ted.com. It is worth a watch! Not to mention, she is an adorably charming lady  :)

http://www.ted.com/talks/elaine_morgan_says_we_evolved_from_aquatic_apes.html

Glad to hear the book is good!

bngenoh:

--- Quote from: SethianSeth on July 27, 2011, 01:21:10 AM ---That book had been on my list after seeing her wonderful lecture on Ted.com. It is worth a watch! Not to mention, she is an adorably charming lady  :)

http://www.ted.com/talks/elaine_morgan_says_we_evolved_from_aquatic_apes.html

Glad to hear the book is good!

--- End quote ---

Me too, glad you started this thread Laura. I found this i think it is a lecture/essay by Elaine Morgan. Its from this site http://users.ugent.be/~mvaneech/Symposium.html. Just click on her name. Now lets start quoting.

--- Quote ---The crucial question about human evolution is why humans differ so strikingly from the African apes despite their close genetic relationship. Most Darwinists would agree that such differences are usually attributable to differing environmental pressures; and hence that our ancestors at some stage probably occupied a significantly different habitat from the ancestor of the gorilla and the chimpanzee.

[...]

Alister Hardy's suggestion in 1960 that it might have been a much wetter one was intuitively and almost unanimously rejected. Primates were said to have an innate fear of water which many humans share, and the fossils of early hominids were found far inland, in arid sites on the African plains. Above all . Hardy's ideas were felt to be unnecessary. There was a tacit assumption that the main ape/human differences had been adequately accounted for in terms of a move by some populations of the last common ancestor from the forest to the savanna, and that any details still unexplained were well on the way to being solved.

That was a misconception. Consensus on the reasons for the emergence of the most salient distinguishing features of Homo - such as bipedalism, loss of body hair, subcutaneous fat, and the power of speech - is no nearer today than it was in Darwin's lifetime.

Bipedalism

Humans are so accustomed to erect locomotion that it takes a specialist to appreciate what a bizarre and costly adaptation it was. Owen Lovejoy commented: " "For any quadruped to get upon its hind legs in order to run is an insane thing to do. It's plain ridiculous." As a gait it is far more unstable than quadrupedalism; it takes very much longer to learn, greatly extending the period when the female is burdened with the task of carrying the infant; it is a deplorably ineffective defence posture, exposing the most vulnerable organs of the body to the risk of damage or evisceration; unlike in quadrupeds damage to one leg or foot can be crippling rather than a temporary inconvenience.

[...]

In any cost/benefit analysis the advantages of erect locomotion must have been very great to outweigh these drawbacks. The aquatic model suggests that in a flooded habitat, bipedalism may have been resorted to under duress, the significant reward being the ability to breathe air. In terms of the savanna scenario the suggested benefits have been many and varied and no explanation has carried conviction for long. At first bipedalism was depicted as an improved method of covering long distances . But running on two legs is slower than on four, and consumes no less energy. It is true that at walking speeds a modern human consumes less energy than a chimpanzee, but it must have been millions of years before this benefit accrued. In one experiment, a human volunteer constrained by an orthopsis to adopt the bent-knee-bent -hip gait practised by the early hominids used twice as much energy as we do today.

[...]

Sentinel behaviour was once a favourite hypothesis since many species stand erect to scan the horizon; however in non-human species this never develops from postural to locomotor bipedalism. A weapon-bearing scenario lost ground when bipedalism was found to have preceded any indication of the use of weapons. A food-carrying theory based on pair-bonding in the interests of the slow-developing young was weakened by the discovery that the slow-down of development post-dated the advent of bipedalism. A thermoregulatory hypothesis suggesting that erect posture lessened the sun's mid-day heat load on a savanna primate became less credible once it was accepted that bipedalism preceded the emergence of savanna conditions. Picking fruit from low bushes has been observed to induce chimpanzees to stand up on two legs - but not to walk around on them. A study was published in 1994 based on 700 hours of observation of wild chimpanzees in a mosaic habitat. The open savanna was the place in which they were least likely to display bipedal behaviour, whether postural or locomotor. The net result of all the speculations is best reflected in a frank statement by two of the early theorists, Sherwood Washburn and Roger Lewin: "We have to admit being baffled about the origin of upright walking. Probably our thinking is being constrained by preconceived notions."

[...]

On the other hand, in recent years gorillas, chimpanzees, Japanese macaques and proboscis and other monkeys have been filmed or photographed exhibiting wading behaviour in the wild, either crossing streams, entering the sea, or wading into pools in search of succulent food items. There is some limited evidence that species most frequently obliged to wade through water, such as proboscis monkeys and bonobos in swamp forest areas, are likelier to stand erect and occasionally walk bipedally on land. It has thus transpired that choosing, or being obliged, to walk through water, is the only circumstance known to conduce to sustained erect bipedal locomotion in wild primates. If it had earlier been possible to make the same claim on respect of walking on the plain, it would have appeared to constitute a powerful piece of circumstantial evidence for the savanna scenario.

Loss of body hair

The original assumption concerning human nakedness, that the hominids shed their body hair to avoid overheating, offered no valid reason why they would have been more at risk from overheating than other species sharing the same habitat. It ignored the fact that depilating an animal on the savanna raises its core temperature, rather than lowering it The argument that nakedness must have been a necessary concomitant of sweat-cooling is invalidated by the example of the thick-coated but efficiently sweat-cooling patas monkey. The progressive shortening of body hairs until they were functionally useless was not an extrapolation of any existing primate trend. Russell Newman convincingly argued that hairlessness must have preceded the move to the savanna; but the feature is no more frequently encountered, and no more easily explained , in a forest habitat than on the open plains. Human skin also differs from that of primates in respect of its greater thickness and elasticity, a radical transformation of the skin glands, and the way it is connected to a layer of fibrous tissue and a fat layer, described by John Napier as "one of humankind’s greatest unsung hallmarks" and found elsewhere only in aquatic species. William Montagna after years of exhaustive research into all aspects of primate skin, reported in 1972 that the problem of human nakedness continued to defy solution.

[...]

It has been shown that in water, in mammals large enough to accommodate a fat layer of the requisite thickness, a naked fat-lined skin provides better insulation than a coat of fur.

Speech

The naïve teleological explanation of why we can speak and apes cannot is that our ancestors must have had a greater need to communicate, perhaps in order to pass on tool-making skills, or to gain insight into the motivation of conspecifics in a society putatively more complex than a chimpanzee’s. .These examples do not explain why it was the vocal channel that was selected for enhancement, rather than the body-language mode in which the primate order was already pre-eminent. In demonstrating how to make a flint arrow-head, words are both inadequate and superfluous, and in divining the mental states of others, we are still apt to rely at least as much on our eyes as on their words. ("I could tell by his face that he was lying.")

While speech is unique to humans, the physical modifications that made it possible are not. Humans but not apes can consciously exert control over the volume of air they inhale, how long they hold it, and how quickly they exhale it. The only other mammals known to be capable of this are diving mammals. It was an essential precondition of speech and the lack of it in apes is an entirely sufficient explanation of why they cannot be taught to speak.

[...]

Fat.

Homo has been described as an obese species; even the slimmest human has the potential for obesity since humans inherit ten times as many adipocytes as would be expected in a mammal of our size. The percentage of fat in a human neonate is greater than that of any other newborn land mammal . It is more than in the harp seal or the sealion, and about six times as much as in a baboon. After birth the baby - despite the high energy requirements of its growing brain – continues to devote roughly 70% of its growth potential to increasing this fat deposit, reaching peak adiposity of around 25% of its body mass by the age of nine months. These facts would not be predicted. either as part of the inheritance from early arboreal ancestors nor as adaptations to a life on the plains of Africa.

One suggested explanation stressed the need of storing energy against possible food shortages, as in hibernating mammals. But the fat in humans is not seasonal, and it is hard to see why natural selection in the hominids would have given priority to food storage in a savanna habitat where speed seems to have been the prime requirement of most other animals whether predators or prey. The other favourite hypothesis is thermoregulation, stressing the cold of the African nights as other thermoregulatory theories stress the heat of the African days.

The attribute of fat to which least attention has been paid is that it provides buoyancy. The amount of fat in diving mammals is liable to vary according to whether they are surface feeders, or deep divers for whom too much buoyancy would be an embarrassment. It is worth noting that a human baby – apart from adapting happily to the water if introduced to it early enough – will float, whereas a chimpanzee or gorilla infant would sink.


--- End quote ---

The specific place is here http://users.ugent.be/~mvaneech/Morgan.html.

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