What is the Aquatic Ape Hypothesis (or AAH)?
In 1972 a book: The Descent of Woman by Elaine Morgan, was published. In it Morgan presented her hypothesis that human evolution had included an aquatic phase. That it was during this aquatic phase that hominins had become bipedal.
The origin of this hypothesis began when Morgan attended a lecture by Sir Alistair Hardy, a prominent biologist. During this lecture he mentioned that humans store fat in a subcutaneous layer over their entire body, just like aquatic mammals do (i.e. seals, whales, otters, etc.), It was from this comment that Morgan began to think that if we shared this trait with aquatic mammals it must be because we once shared a similar life way. We had once been aquatic and thus this fat storage characteristic was a retained trait that had once served to insulate us against the heat-sapping effects of living in the water. At this time the most common /accepted hypothesis for the origin of bipedalism was the “Savanna Hypothesis. This hypothesis was that during the Pliocene (a geological time period between the end of the Miocene and the beginning of the Pleistocene, believed at the time, to extend from 12 to 1 million years ago) the climate changed to be warmer and dryer (the long, torrid Pliocene was how it was described in one book I read). This resulted in the a reduction of the area covered by tropical forests and in increase in the covered by savanna grassland. As the forest shrank a species of ape “climbed down from the trees” and began to live on the ground in the open savanna. This ape started walking upright on its hind legs and to use tools.
If you have ever seen the opening scenes of the movie “2001: A Space Odyssey,” where a chimpanzee-like ape picks up a thigh bone and smashes a skull, then he, wielding the thigh bone, leads these apes in an attack on another group of apes over access to a waterhole. During which attack the leader strikes and kills the opposition leader, beating the body multiple times with the the bone before tossing it spiraling upward to morph (to the tune of the waltz “Blue Danube”) into a double-wheeled space station rotating it the dark void of space as a smaller shuttle, rotating in unison like two dancers waltzing, approaches for docking, you will have seen a quick synopsis of the Savanna Hypothesis. You will also have hint as to why it is also known as “The Killer Ape Hypothesis.” The other thing about the Savanna Hypothesis is that it is a male ape that becomes a biped and a male ape that discovers tools (more correctly: weapons) and began hunting. Unintentionally, or not, the savanna hypothesis was very sexist. Everything that occurred to make us human was because of male behavior and aggressive behavior at that. Morgan’s hypothesis was the antithesis of this, and deliberately female-oriented. During the long and torrid Pliocene, a female ape came out of the disappearing forests and settled along the seashore. There, living on the beach with her offspring she foraged in the shallows for seafood and fish, evolving biped behavior to be able to search in deeper water without getting her head under water, with her child at her breast. The addition of fish, a high source of protein, enabled her to grow a larger brain. That is her hypothesis in a nutshell. She added more details to this basic idea support to it beyond the sharing with other aquatic mammals of the subcutaneous fat storage. I will not comment further here on what I think of the AAH (that is saved for what follows below). I will only say here that it is not accepted by main-stream scientists and that the savanna hypothesis, as it was then, has also changed to point where it is something very different. I do want to point out three things that have changed since either hypothesis was proposed and it applies equally to both. First, the beginning and end dates of the Pliocene have changed. With the development of radiometric dating methods, their increased use and a better definition of what the boundaries of the various geologic epochs, periods, eras, etc. are, the Miocene-Pliocene boundary is now dated at 9 million years ago. The Pliocene-Pleistocene boundary in also re-dated at 2.6 million years ago. The old dates were 23 and 1.8 million. The Pliocene was not as long a period of time as then believed. Secondly, scientists have developed methods by which we can reconstruct the probable climate when the various sediments were being deposited. The Pliocene was not as hot and dry as once believed. Thirdly, with the discovery of more fossil and prehistoric tools (and better dates), we know that bipedalism evolved by around 6-7 million years ago during the Miocene, the first use of stone tools occurs around 2.6 million years ago (and just possibly 3.39 million), and the human brain begin its enlargement from chimpanzee-sized organ less than 2 million years ago and really expanded in size 500,000 years ago (both dates during the Pleistocene). These facts matter to both hypothesis because they both propose that bipedalism, the enlarged brain, and tool use all occurred around the same time. Doesn’t matter if it was during the Pliocene or not. These three factors evolved close in time to each other, not some 5 million years or so apart in time. Neither hypothesis is right. Now to the main event, so to speak:
The basis for the following was written in a motel room over a period of several evenings while I was working out-of-town in 2004. One evening, the PBS channel had a show on Morgan’s theory. I wrote this in response to it. You might call it a knee-jerk reaction, maybe it is, however I think it represents why professionals, those who know the field, dismiss the AAH without serious consideration.
THE AQUATIC APE HYPOTHESIS, PART 1
The Aquatic Theory of Human Ancestry is so contradicted
by the facts as not to be worthy of rebuttal here.
—Grover S. Krantz (1999:53)
I know that there are people who think that answering Elaine Morgan is a waste of time (as Grover Krantz quoted above), perhaps among the scientific and anthropological community it is. However, the Aquatic Ape Theory or more accurately the Aquatic Ape Hypothesis (AAH) keeps surfacing (pun intended) and many lay people think it is a good theory. They also believe, correctly in a few cases, that the scientific community is not giving the theory a fair hearing and are just “blowing it off.”
So perhaps answering Elaine Morgan can be of some use and can show how the AAH is an example of poor science—poor data, and poor methodology. It is ignored without much of a hearing, and with valid reasons. The AAH will never quite go away but maybe it can be shown why science has mostly ignored Morgan—we know it made no sense from the beginning.
Scientists are often accused of dismissing some theory or other out-of-hand, of being biased against certain ideas and not be accepting them, of not even being willing to consider the possibility that an idea might be true because of a preconceived notion. We, scientist and non-scientist alike, do this. We are prone to reject or accept some ideas without a second thought, be they ideas like evolution, continental drift, ESP, reincarnation, Atlantis, ghosts, or unicorns. We all have a concept of what the world is like and how it operates. Any new idea which appears to fit into our “scheme of things” will be readily accepted. If it doesn’t appear to fit it will be rejected or seriously doubted. If it is really contrary to out ideas about the world it may continue to be rejected in the face of overwhelming evidence, a dogmatic refusal to accept the facts.
As an example, many scientists are accused of being dogmatic and refusing to accept the evidence for ESP and other paranormal phenomena. A scientist who counters that there is no scientific evidence and that the anecdotal evidence is conflicting and usually open to other non-paranormal explanations, is accused of being willfully blind. Personally this is where I fall, there may be paranormal phenomena but there is no scientifically acceptable evidence for any of it (emphasis on the “scientifically acceptable evidence”). All of the “scientific experiments” done are so poorly designed that they fail to meet proper scientific standards, fail to exclude non-paranormal causes and are only “proof” because the experimenter found what they wanted to find.
Paranormal phenomena are so at odds to what scientists know about how the physical world works, appear to violate so many laws of physics, chemistry, etc. that its existence amounts to extraordinary claims about the real nature of the world and how it works. If these phenomena exist, understanding them, accepting their existence would require a huge change in how we view the world, the “paradigm shift.” As is said: “extraordinary claims require extraordinary proof,” and that just doesn’t exist, not yet anyway.
Theoretically a real scientist does not dismiss all theories that do not fit his preconceived ideas. He is supposed to dispassionately, objectively review the evidence and then make up his mind. If a scientist, or non-scientist, actually did this with every idea that came his or her way, all of their time would be spent at it and they would waste a lot of time examining and testing truly useless, false, and crackpot theories. So we all have “filters” to screen out wrong theories so we concentrate on the potentially correct ones. Issac Asimov called it “his built-in doubter.” The problem then is to not throw out the true-but-on-the-surface-weird-theories with the truly crackpot and false theories. Continental drift was one of these that got thrown out when first mentioned but later gained scientific respectability. When Wegener first postulated that all the continents had at one time been joined together in one large super-continent that had later broken apart and the continental fragments had “drifted” to their present locations, he was pretty much laughed and the theory rejected out-of-hand. It didn’t fit with the idea of a rigid crust, how could the continents “plough” through the oceanic crust? About the only evidence Wegener had for his idea was the apparent similarities of the coastlines of opposing continents. This was not enough to change most people’s minds.
In the following 50-60 years accumulating evidence from multiple and independent lines of research, particularly facts about the oceanic crust, pointed more and more in the direction of Wegener’s theory, although from kind of the opposite direction. Studies of the ocean bottom showed that the sea floor had/was being created at mid-ocean ridges and spreading out from there—sea floor spreading. The Atlantic Ocean was growing wider. If the oceanic crust was moving like a conveyor belt, and the continents were attached to the crust, they too must be moving, not “plowing” through solid crust but moving with it. Wegener was right after all and geology made this large shift in their paradigm. (The Rejection of Continental Drift by Naomi Oreskes, 1999, Oxford University Press, is an excellent study of the rejection and later acceptance of continental drift.)
Wegener had made an extraordinary claim without the extraordinary evidence, Geologists were correct in dismissing his theory, at the time. Further research, even if it wasn’t aimed at proving or disproving Wegener’s theory, accumulated an extraordinary amount of evidence that could best be explained with Wegener’s theory, and it is now accepted. It is scientifically tested and to refuse to believe it now is not scientifically sound. It fits the known facts and explains far more than just the shape of the continents. Claiming continents don’t drift would now require extraordinary proof.
Elaine Morgan claims that her “Aquatic Ape Hypothesis” explains, scientifically, the known facts better than the “Savanna Hypothesis,” as she calls what was then the generally accepted theory of human evolution. (The “Savanna Hypothesis” itself has changed much in the intervening years.) This is not exactly an extraordinary claim, like continental drift was, but it would require a larger change in the accepted human evolution paradigm than whether hominines were hunters of scavengers.
Wegener started with the observation that the Atlantic coastlines of Europe, Africa, South America, North America, and Greenland could be “fitted” together to form a single super-continent. From this he hypothesized that they had in fact once been joined together and had split apart and “drifted” to their present locations. He supported his argument with some other known facts about the distribution of fossil species, geologic formations, glacial deposits, etc. He did not develop his theory much further, he died soon after publishing it, and it lay “fallow” for about 50 years before being dusted off and refurbished because of new evidence.
Theories often start this way—with an observation and a hypothesis about what the observation might mean. Scientifically you proceed by making one or more predictions based on the hypothesis that can be tested by experiment. The experiment can be the collection of more facts. The results are compared to the predictions and the theory is either supported or not. This is basically how the scientific method is supposed to work.
Elaine Morgan started with the 1930 observation of a zoologist (Sir Alistair Hardy)(#1) that the body fat on humans is distributed about the body the same way it is on aquatic mammals (seals, whales, walruses, dolphins, etc.).(#2) This distribution is different than that on land mammals. To explain this observation Hardy hypothesized that the subcutaneous fat on the human body is distributed the same way as on aquatic mammals, and different from terrestrial mammals, is for the same reason: heat retention while in the water. We shared a similar evolutionary heritage. We were once aquatic, hence the name Aquatic Ape Hypothesis. Morgan did further research and marshaled a number of other observations (we will get to them in a moment) that she claimed could only be explained by our having passed through an aquatic phase in our evolution.
Morgan’s theory was rejected by the majority of scientists without much of a hearing. She claimed they were biased and refused to consider that their theory (the Savanna Hypothesis) did not explain the facts and observations as well as, or at all, as her theory. And they simply refused to consider it because she was not one of them, she was an outsider. The professionals said that her facts were explainable in ways that didn’t require an aquatic phase, that her theory was contradicted by the mass of other facts and observations that were readily explained by the Savanna Hypothesis. They did not give it a “fair hearing” because anyone who knew the literature (#3) would realize that the evidence was against it.
When I was an undergraduate (last century, literally) I was intrigued by the idea of the “Killer Ape.” Reading Robert Audrey, the leading proponent of the concept, was what drew me to paleoanthropology. I wrote a paper about the possibility of man being inherently aggressive. It was based on the reading I had done. My professor (and faculty advisor) commented that with an in-depth knowledge of the literature I would have come to a different conclusion. (Apparently he thought that as it was a term paper rather than say a thesis and I didn’t have the years to acquire that in-depth knowledge, that based on what I did know, I had written a good paper. He gave me an A- for it.) I have that in-depth knowledge now and he was right. I have come to a different conclusion.
With a superficial knowledge of human evolution, the Aquatic Ape Hypothesis sounds plausible, but the more you know . . .
Because I have based the above rebuttal of the AAH on what was presented in the documentary I am sure that I don’t have all the fine details and the presentation lacked depth, mentioning only the major points and not presenting all the evidence. I know that, however I think that I can show that the major points are wrong, so wrong further details and evidence can’t possibly change the result. Furthermore, I have “handicapped” myself by using only what I remembered of the literature while sitting in the motel room. I checked a few details when I returned, mostly on osmosis in fresh and salt water, to make sure I had my facts right. I did not and have not done research on the topic, this is what I know. This is also why there are no cited sources. I was going to do research (i.e. read Morgan’s books) but decided to leave it as I wrote it (beyond some minor changes to make it readable, corrected the grammar, spelling, etc.) to show that further research is a waste of time, at least of my time, there is not enough value in the hypothesis to make it worth further consideration. You tell me about Morgan and the AAH, this is what goes through my mind when I reject it without “serious consideration” or a “fair hearing.”
From the documentary the AAH is based on the following observations (in no particular order):
1) The distribution of subcutaneous body fat on humans is similar to that of aquatic mammals and different from that of terrestrial mammals.
2) Hominines are the only savanna mammals that are hairless.
3) Hominines are the only savanna mammals that are bipedal.
4) Fish and other seafood are “brain food” and supply necessary nutrients, proteins and fatty acids needed to evolve a big brain; the enlarged human brain evolved rapidly and early in our evolutionary history.
5) Man is the only mammal with voluntary control of breathing. We have this control because we were adapted to diving. This is a factor in our language ability.
6) Primates walk upright in water to keep their noses above water so that they won’t drown (they cannot hold their breath). This is why hominines became bipedal.
7) Hair on our body is arranged in a way that follows the direction that water flows along the body when we are swimming (reduces friction and is comfortable—not being “rubbed the wrong way”). The long hair on our heads, especially the longer hair on females, allows the infant hominid to hold on and not float away.
8) Human infants put on a lot of fat just before birth and for one year after birth. Also they can hold their breath (cf #5 above) and swim just after birth. The fat aids floating.
9) Quadrupedal running is faster than bipedal running so there must be some other explanation for the evolution of bipedalism than simply as a means of locomotion (cf #6 above).
10) Humans require a lot of water, savanna mammals are adapted to arid conditions by reducing their need for water.
11) The Savanna Hypothesis has failed to explain man’s evolution, therefore the Aquatic Ape Hypothesis is true.
The above observations are the major “facts” indicating an aquatic phase in hominid evolution. The AAH also has a model for the when, where, and why hominines became aquatic.
Hominines were aquatic just at or immediately after the separation between the apes and the evolutionary line leading to humans. Our adaptation to an aquatic habitat was the cause of this division, it was this radical shift in habitat and life style that led to hominid evolution.
The Danakil Depression is a triangular shaped area of Ethiopia and includes Djibouti and the Afar region where Johanson found Lucy. According to the AAH, about 6mya (million years ago) this area was flooded except for a large island. A group of apes were isolated on this island and either “naturally” or by force of circumstances became aquatic. I don’t know that the AAH explains how or why these aquatic apes reverted to being terrestrial, the documentary didn’t deal with this part. Presumably it has to do with the Danakil Depression being uplifted and becoming dry land, the aquatic apes “naturally” becoming terrestrial again and re-occupying the savanna. This is what I think the AAH model would be, however it isn’t really important and, in any case, I won’t hold the AAH to it.
The AAH may seem to be a well-founded, sound, and scientific theory. The TV documentary presented it as such and implied that it was a viable theory, that, even if not true in all its details, it had a lot to say about human evolution. Its lack of acceptance or serious consideration by the scientific community was due more to a biased refusal to consider any thing other than their Savanna Hypothesis than by consideration of the AAH’s merits.
Most members of the scientific community and those well informed on human evolution know that the AAH has no basis, and doesn’t merit any real study before being rejected. This “biased” rejection is because the major facts or observations that the AAH is based on don’t hold up under closer scrutiny. The scientific community senses this. The problem is that they just sat “no” without articulating the reasons.
On a point-by-point basis here is why I and (I believe) most of the scientific community (the “professionals”) reject the AAH:
1) I remember reading somewhere that the distribution of body fat on humans is not different from the distribution on the other land mammals. Actually, I think that it is not similar to that of aquatic animals anyhow. Their fat is distributed more or less evenly over their entire body to form an insulating blanket (and provide for streamlining the body).
Any well-fed mammal can have layers of subcutaneous fat over their entire bodies. Talking about fat distribution in humans using well-fed western Europeans and Americans as the human “baseline” is wrong. These are “tame” or “domesticated” animals and do not represent the “wild” condition (cf #8 below).
Human fat distribution is localized (breasts and hips on women and the belly on men). This is a characteristic of desert-adapted animals (e.g. the humps of camels). Storing fat in local areas rather than evenly across the body allows for the accumulation of large fat reserves without forming an insulating layer over the body (the role fat plays in aquatic mammals) that would seriously interfere with heat loss, causing overheating.
2) Elephants, rhino, and warthogs are savanna animals that are at least as hairless as humans, so hominines (if they were actually hairless) are not unique in this respect. Hairless-ness is not an adaptation unique to aquatic environments. It may be an adaptation to a totally aquatic life (e.g. whales, dolphins, and manatees) but some aquatic mammals or particularly semi-aquatic mammals (which hominines must have been to have been able to become terrestrial later) like beavers, muskrats, polar bears, etc., have fur. Man’s hairless-ness is due to some other factor. The Savanna Hypothesis postulates that hairless-ness is an adaptation to allow more efficient cooling by sweating. Hair on the head was retained to protect the brain from overheating (we use hats now). Hair in the armpits and groin provide better “scent traps,” a role that would not work in water.
3) Humans are the only bipedal mammals on the savanna or elsewhere. Bipedalism is unique and it does require some special explanation or cause for its evolution in hominines. This does not automatically mean that it has to an adaptation to a watery environment. An aquatic environment is no more unique than the savanna. It might be an explanation if mammals adapting to being aquatic were more likely to evolve bipedal locomotion than mammals adapted to other habitats. But aquatic mammals are not more bipedal, in fact none of them are. Only one mammal is bipedal and we live on land. We are much more adapted to striding long distances than swimming the length of a pool. (Any human walks constantly and many miles, it is the trained athletes that swim any great distance. I can walk miles, my single day record is 21½ miles. Five or six miles is something I can do with hardly a thought. Swimming a mile took me a summer of training and 100 yards would be hard going for me now.)
4) Fish and other seafood may provide enough nutrients, protein, and calories to allow the brain to reach its genetic potential, but the brain will not automatically grow larger and grow faster just because it is well nourished. Its growth is governed by both nutrition and genetics. There must be a positive selective pressure for a larger brain for a larger brain to evolve, not just more “brain food.” Other fish-eaters do not have higher than expected EQ values,(EQ is “encephalization quotient,” a ratio of brain size to body size) larger brains than expected for their body size. In the documentary there was a remark about how dolphins had brains large brains and how hard it is to catch fish. Then it implied that dolphins had brains far larger than they need just to catch fish, which are easy to catch. (I know it contradicts the previous sentence, this is not the only contradiction in the AAH argument.) Therefore eating fish causes brains to grow big. I don’t think that dolphin brains are larger, not for an animal their size and if you have ever tried fishing you will know that it is not always easy to catch them. Mammals have larger brains, size for size, than fish, so an aquatic mammal will have a larger brain to start with. Fishing may not require a big brain but having one won’t hurt (especially if you start with one). Besides dolphins are social animals and that alone requires a larger brain.
I suspect that using dolphins as an example of “big brains” is because they have that bulging forehead, just like humans, so they must have big brains just like humans. Unfortunately, that “brainy”-domed forehead encloses an oil-filled “melon” which is used in the production and to focus their sonar, it is not the brain. Sonar, by the way, must require a large part of the brain to process and interpret the signals, that alone could explain any unusual brain expansion in cetaceans.
Anyway human brain expansion occurred very late in our history, not at the beginning as the AAH predicts.
Human groups that eat a lot of fish are not known for having brains larger (either relatively or absolutely) than the rest of us.
5) I am not quite sure what is meant by “voluntary control of breathing.” This is supposed to be an unique adaptation to diving. Certainly it can not mean just the ability to hold your breath, every cetacean, seal, otter, etc. can do that. Also it cannot mean that we alone of all mammals can inhale and exhale various volumes of air at various velocities, as in singing and talking. Bugling bull elk or elephants sucking water up their trunks to spray over their backs show that other animals can do that.
The documentary used some footage of proboscis monkeys to show that primates can and do, naturally, explore and forage at the water’s edge. The narrator told how the monkeys would also swim and dive in the water. So the proboscis monkey must have “voluntary control of breathing,” and humans are not the “only mammals” as claimed. The proboscis monkey in sot aquatic or even semi-aquatic although it may be on the road to it. The point is, it isn’t yet aquatic yet they can control their breathing (a future (exaptation?). Therefore being aquatic is not a “necessary and sufficient” cause.
6) AAH implies (in the documentary) that we had to walk upright to avoid drowning because the water was too deep to cross quadrupedally. AAH also implies that we were in the water supposedly foraging for food, not to cross it. The problem here is how do you forage for shellfish, etc. on the seafloor in neck deep water without diving? We couldn’t dive because we couldn’t yet hold our breath, if we could have held our breath we wouldn’t have to have become bipedal to keep from drowning. The logic escapes me. We should have evolved extra long arms like the gibbons so we could avoid bending over. Besides we have already shown that man is not unique in having voluntary control of breathing (cf #5 above). We could probably hold our breath whether to dive or to cross rivers quadrupedally no matter how deep.
Using the line of argument that we became bipedal to cross deep water predicts that quadrupeds cannot cross rivers more than “nose-deep.” From this it follows the hundreds of thousands of zebras and wildebeests that annually cross the Mara River in the Serengeti should all drown because they are not bipedal and have to swim the deeper portions. Some do drown, just as hundreds of buffalo drowned crossing the Missouri River, but not all. They swim when the water gets to deep to touch bottom.
7) I don’t think the pattern of our body hair is really any different from that of other mammals. Morgan (actually the TV documentary in this case) presents no evidence (comparing and contrasting with other mammals), just anecdotes and personal opinion. Most (or all?) mammals’ hair runs front-to-back and from top-to-bottom, as “perfectly” adapted to swimming as our own hair.
The hair on our head is long, especially on females, supposedly so infants can hold on while floating in water. This ignores the fact that longer hair on women is for cultural (culture defines hair styles). Men can and do grow hair just as long as women. Anyway long and straight hair is a recent trait, originally it would have been like body hair—short and possibly curly.
The argument here requires that hairless-ness and, at least moderately, helpless infants occurred early in hominid evolution. Supposedly hairless-ness is a requirement for an aquatic life (see #1 above) ignoring fur seal, otters, etc. The infant had to hold on to the mother just as baboon and chimpanzee babies do, for a period of time after birth. Ignoring whether hominid babies were born on land like seal pups or underwater like whale calves, no aquatic mammal requires its infants to hold on to the mother. Why should an aquatic ape? This “evidence” is put forward in connection with how a hairless bipedal female has to carry in her arms the helpless infant and because this is hard to do while foraging (is it really?) we must have been aquatic since human babies float (see #8 below) and females have long head hair. Why not just leave them on the beach with an older child or adult babysitter to watch. (Question: How well do human infants grip at birth? It should be much stronger than our nearest primate relatives since the infants’ lives depended on it. This is a prediction of the AAH and it could be tested.)
Primate and prosimian babies hang on quite well as their mothers go leaping and crashing through the trees. Ah! you say, but their mothers have fur and the infants are not as helpless as modern human infants. Precisely, only Morgan requires hairless-ness and the very helpless and slow growing infant evolving as early in our history and at the same time. Helplessness is a compromise due to a bipedal ape with narrow hips trying to give birth to an infant who need to grow a large brain. For other animals brain growth occurs in the womb, we are born premature, before the head is too big for the birth canal. This is only a successful way because the female has social support system (the family and band) that “allows” her to devote so much effort to caring for such a helpless infant for so long. Now bipedalism and the enlarged brain (with the consequent delayed maturation) evolved about 3.5-4.0 million years apart (so the fossils indicate). When hairless-ness evolved we don’t know. A bipedal ape with some hair would have no problem carrying an infant with the physical capabilities of a chimpanzee or gorilla infant. And yes, even a hairless chimpanzee female would be hampered and that’s the point: naked bipedal females would have restricted movement for the time it would take the infant to start to walk. She could forage a “berry patch” with no trouble and carry the infant over the long distances and in a few months the infant could keep up (just like chimpanzee, gorilla, baboon infants, etc.).
By the time the period of extreme helplessness began to appear and increase in length, humans were fully bipedal and certainly hairless, they also had social groups and the rudiments of culture (learned, shared behavior and probably the force behind the increased brain size). Humans used culture and social organization to help raise these helpless infants.
8) Is this true of all human infants or just those well-fed and over-fed western European and American infants? AAH predicts that all human infants gain unusual amounts of fat. I suspect that any well-fed mammalian baby that gets more calories than its body immediately needs for building bones and muscles puts down layers of fat, that human infants are not unique in this.
Of course, a human infant can hold its breath, it has control over its breathing. It cries and coos, just as kittens mew and puppies whimper. There is nothing special about this and sure, a baby can float. I suspect most mammal babies can, animal bodies are less dense than water. As for “swimming,” maybe “crawling” is a better term. A baby will lie on its back and move its arms and legs (flail about). Turn the baby over and place it in water and look—it’s “swimming.”
The fat serves just as well to provide some insulation to help regulate the body’s temperature (babies lose heat faster than adults and don’t produce as much) as to provide “flotation” and insulation against heat loss to water. Adaptation to an aquatic habitat is not a “necessary and sufficient” reason.
9) So horses are faster than us? They evolved for speed and obviously we didn’t. The other explanation is that bipedalism is better than knuckle-walking. We are built for distance walking and as a “jack-of-all moving-trades,” not as a specialist in speed. Locomotion is not just about speed.
10) Most well adapted desert and semi-arid organisms are adapted to reduce their water requirements. So we’re not well-adapted, we’re just “well-enough-adapted.” We cool by sweating (more efficient if you don’t have any body hair), with enough water to drink and low humidity (like the East African savanna) we can tolerate high heat levels.
Being aquatic, like fish, brings up other water problems. In fresh water an animal’s blood and tissues have a higher concentration of salts, etc. than the surrounding water (hyper-osmotic). Water is steadily absorbed through the skin and salts lost. Therefore a large volume of dilute, low-salt urine is excreted and salts must be taken in to maintain an internal balance.
In sea water, tissues and blood are less concentrated in salts and ions than the surrounding salt water (hypo-osmotic) and will constantly lose water to the environment, therefore fish must consume large volumes of water and excrete excess salts. Now we cannot drink salt water, so if we were adapted to life along the ocean we should need a source of freshwater, not a really good adaptation.
The argument here is that since we need so much water we must have evolved in an environment where water was plentiful (not the ocean since as Coleridge said: “Water, water everywhere and not a drop to drink”).
How about we originally adapted to the tropical forest where there was water and we didn’t use much to keep cool. Then we began to shift to hotter, more arid environments, adapting to the increased heat load by sweating, changing body proportions, keeping head hair, having hairless bodies, and sticking “close” to water, going no further than we could walk, forage, and return to drink (which could be a fair distance being good walkers), or maybe we just stuck to the riparian woods.
11) The Savanna Hypothesis has hardly failed, it explains things better than the AAH, including the AAH’s own points. Besides even if it has failed that does not mean that the AAH is therefore true. The truth of any theory is dependent on the facts, its ability to explain them, make predictions, and accommodate new facts, all of which the Savanna Hypothesis does much better than the AAH. In fact the AAH fails miserably and is readily falsified (e.g. large brains evolved at the same time as bipedalism not, as is true, at different times, see #8 above).
The AAH is based on a flooded Danakil Depression, flooded by seawater, isolating an ape population on an island (apparently riverine and lake environments are not forceful enough). These apes became bipedal, hairless, large-brained hominines with a physiological need for quantities of freshwater. Yet marine environments, especially along the desert shores of the Danakil, would be as bad or worse place for finding fresh water as the savanna. The AAH makes predictions (not that its supporters recognize this) which don’t stand up. We find hominid fossils in inland environments (riverine, shallow water) and not coastal environments. Bipedalism preceded the large brain by 3.5-4.0 million years, they did not occur together.
The AAH makes predictions about what we should find if new fossils are found, new data or tests done. The supporters don’t make these predictions, don’t do the experiments (which is part of the scientific methodology). They prefer to show how their theory “explains better” the supposed anomalous facts of the “Savanna Hypothesis.” They do not demonstrate that their theory is a better predictor or that the AAH is the only explanation that fits all the known facts. (I hope that I have shown above that it does not predict or explain any of the facts.) Their “scientific methodology” is similar to that of the “creation scientists,” that is: it only sounds scientific to those who don’t really know what scientific is.
#1 Alistair Hardy (1896-1985) based his remark on a comment in F. Wood-Jones 1929 book Man’s Place Among the Mammals that humans had fat attached to the skin. Hardy realized that this “sounded” like blubber. See Hardy A., Was Man More Aquatic in the Past? The New Scientist 17, March 1968, pp. 642-645.
#2 Elaine Morgan has written four books:
1972 The Descent of Woman.
1994 The Scars of Evolution: What Our Bodies Tell Us about Human
1995 The Descent of the Child: Human Evolution from a New Perspective.
1984 The Aquatic Ape: A Theory of Human Evolution.
#3 The corpus of written material on the subject.
THE AQUATIC APE HYPOTHESIS, PART 2
After writing the “instant” response above in the motel room (see previous post, The Aquatic Ape Hypothesis, Part 1), I did read her book and here is a more informed response with further details and comments:
The Descent of Woman: A Critique
“. . . Both they [the enigmatologists] and the other pseudoscientists seize upon the possible as if it were the probable, fantasize behind a mask of rationality, multiply entities beyond necessity and refuse to test their hypothesis.”
—David Kahn, The Codebreaker, 1967:889.
One of the reasons why Morgan’s AAH was not well received by the scientific community was because she was an “outsider,” a dilettante amateur. There is an unfortunate tendency among humans to reject out-of-hand ideas that come from people who are not part of whatever group we have created. This is unfortunate because we become parochial in our views and knowledge and can make very good use of ideas and information from other disciplines.
Morgan has made a valuable contribution to paleoanthropology by forcing us (most of whom are men) to consider the part women played in hominid evolution, and by making us rethink our theories. However her hypothesis should not be accepted solely because it is “non-sexist” or feminist, but on its ability to explain and or predict evidence and its logical consistency. Here she fails, and in a large part because she is an “outsider,” a dilettante. She lacks an in-depth knowledge of the literature of the various disciplines she draws from, nor does she have a broad background in any of them. Furthermore the way she structures her argument, the facts she uses, and the way she uses them shows her lack of understanding.
Morgan came up with the theory first then went looking for the facts to support it. Unfortunately this is how most of us do it. It is like the paranoid person, if you accept the first premise (they are being persecuted), everything else it readily explainable, or else just ignored. Supposedly the way to do it, is to collect facts and see what they show. Realistically we do start with a theory (actually an hypothesis) and then gather the evidence. This can work if you consider all the evidence and correct your theory to fit the new evidence. You do not adjust your evidence to fit your theory.
Morgan points out, quite correctly, that proponents of the savanna hypothesis are sometimes vague about how or why hominines became bipedal or began using tools, saying that their theories are “just-so-stories.” However she then creates a vague just-so-story of her own. Some of her arguments are circular, some of her examples are irrelevant, and the sequence of when adaptations happened is confused. She picks and chooses what supports her theory and ignores the rest. She points out facts the contradict the savanna hypothesis, but never the ones that might support it. According to her, the “torrid” Pliocene set in so rapidly there was not enough time to adapt to the new conditions and survive on the savanna (although all the other savanna mammals were able to adapt). Only retreating to the sea provided a buffer to give time to evolve, but we adapted to the sea instead. We became bipedal, naked, and very human in shape. There was enough time for that but not enough for more than partial webbing of the digits (for a few humans) and then the beginnings of glands to remove excess salt (tear ducts). Ten million years and “she” had hardly begun to adapt. Whales went from four-legged terrestrial mammals to a totally marine mammal in about the same amount of time.
Also, hominines lost their fur because it was uncomfortable when wet, tails were dispensed (#2) with because they were in the way, buttocks became enlarged because sitting on sand and rocks was uncomfortable. Things evolve because the hominines wanted them. This is not how evolution works. Morgan is a Lamarckian. Her theory is “simpler” than others, and that is why it is true. Her explanations are just as simplistic as the others and for the same reason. She glosses over, doing the same thing that she complains, and rightly so, that others do.
She does not understand evolution, and she does not understand how to construct a logical argument. She contradicts herself and is circular in her arguments. What happens early hasn’t happened yet later, her sequence of events isn’t clear and consistent. Many things occur because of a helpless, slow-growing, naked infant (apparently she assumes this to be a fact because contemporary infants are), although in the beginning the hominine infant was similar to any other primate infant. The helpless, slow-growing part only comes with the big brain, with a bipedal female giving birth to a large-brained infant. Morgan herself says these hominines had small brains. They were ancestors to the australopithecines who had chimpanzee-sized brains and infants that grew at the same rate as do chimpanzees. The Taung child, the first austrolopithecine fossil found, was originally estimated to be 6 years old at death (based on human development rate) was probably actually 3 years old (based on a study of the growth markers in its teeth).
Morgan explains the evolution of the human nose as an adaptation to keeping water out of our sinuses when swimming and diving. If we had noses like gorillas we could not keep water out, so we grew noses that extended out from our face and had nostrils pointed downward. This supposedly keeps water out. Seals and other aquatic mammals use muscles to close their noses. You would think that after ten million years we would have come up with something better than a nose with slightly downward opening nostrils. I get water up my nose frequently when in the water so my nose doesn’t work real well keeping water out. (I have a nose clip to keep water out of my nose when I am practicing “rolling” my kayak.) Morgan points to the proboscis monkeys as an example that this is a natural way for primates to adapt to an aquatic habitat. Actually she does not claim that they are aquatic. Proboscis monkeys live in lowland rain forests and mangrove swamps and they have been seen swimming and diving in the water. They even have partially webbed feet. The noses of adults are well developed, extending beyond the lips becoming pendulous in males (they have been liken to Jimmy Durante, for those who remember him). The nostrils of the adults open downward, in infants the nose still turns upward. The fact that the nose does not fully develop its characteristics until adulthood and is much larger in males than in the females (sexual dimorphism) has led primatologists to assume that it is a secondary sexual characteristic (like human beards, female breasts, etc.)and is the result of sexual selection. The primary “use” of the nose is to attract the opposite sex. Why hominines with ten million years of aquatic life developed a nose nowhere near as large or downward pointing as the proboscis monkey, or only a little bit of “webbing” between the thumb and index finger (so little I bet you never even thought of it as a web (a small percentage of people have a little bit more webbing between their fingers than the rest of us), while the proboscis monkey, which is not aquatic has partial webbing between all the fingers and the toes. I don’t understand. They are much more adapted to the aquatic life Morgan hypothesizes for our ancestors than we are. Maybe our nose is more of an adaptation to humidifying and removing the dust from the air of the arid and dusty savanna. The lengthened nasal passage provides more space for more hairs to trap the dust and more membranes to moisturize the dry air before it reaches the sinuses, this keeps the sinus membranes from getting excessively dry and they are more efficient at moisturizing the air before it gets to the lungs. The angle of the nostrils is just a result of what happens when a primate nose begins to protrude from the face.
As for the “webbing” (that piece of skin) between the digits of our hands and feet, maybe it is just a “convenient” way to arrange the skin between fleshy digits, an example of what Stephen J. Gould termed a “spandrel.” Morgan would say it is a holdover from our aquatic days, maybe she is right—our aquatic amphibian days?
Morgan brings up elephants and rhinos in the chapter on the hominines’ return to land (which she very casually and cursorily passes over). She uses them as possible examples of mammals which probably were aquatic and have returned to land (#3) (her own idea). Anyway she explains the baggy skin of rhinos, and also elephants, as being caused by their having lost a lot of weight. The rhinos and elephants I have see don’t look like their skin is “baggy” or hangs loosely on their bodies. She says that if you were to “inflate them” (her words) until the skin was tight, they would resemble dugongs or seals, therefore they must have been aquatic and when they returned to land they lost a lot of weight and the skin hung in loose folds the same way that an obese human’s skin does when he or she loses a lot of weight rapidly. Humans are not born fat or with baggy skin. Those of us who have gained excessive weight do not have tight skin. As we get bigger (fatter) the skin grows and if we lose a lot of fat quickly, the skin does not shrink as fast and it does become loose and baggy. Apparently Morgan thinks that this becomes a gene that is passed down (okay, maybe not in humans but in rhinos at least, I told you she was a Lamarckian) and continues to be passed down millions of years later, even though it is maladaptive. This particular point is one of the more ridiculous and senseless ones she makes. However most of the others are only a little less senseless, a little less illogical.
We have a single pectoral pair of mammary glands like elephants and manatees. This is supposedly evidence of an aquatic heritage, not the she gives any evidence for it or that it is limited only to aquatic animals. Linnaeus used this trait as one of the defining characteristics of primates, all primates: prosimians, monkeys (Old and New World), apes, and humans. It is an ancient trait (a symplesiomorphy—a primitive, shared trait for you cladists) and not something that only we humans have (at least among the primates).
She also uses the pig as an example of an aquatic animal that returned to the land. The evidence for this is the animal’s hairless-ness and fondness for wallowing when it gets hot. She is talking about the modern breeds of pigs, the ones bred by humans over the past thousand years or so, not their wild ancestor the European wild boar which is hairy (and also the African forest hog). Oh wait, she did sort of mention them, wild pigs are hairy—a coarse, sparse, scruffy fur because they “forgot” how to grow a decent fur coat while they were aquatic and now that they are terrestrial again they can’t remember how. If wallowing is a sign of an aquatic past then buffalo and elk, as only two examples of animals that wallow, must have been aquatic at one time using her logic.
She picks certain examples to support her theory and ignores others that counter her examples. She ignores the implications of her own logic. She says our enlarged buttocks are an adaptation to provide a cushion to sit on rocky beaches. Other primates have ischial callosities, tough hard pads of tissue on their buttocks to protect their bottoms when sitting (and not just on rocks). They seem to work quite well. Our buttocks are a large mass of muscle: the gluteus maximus. In chimpanzees and other apes it is rather small, not “maximus,” compared the other gluteal muscles. In humans it is maximus because we use it a lot in standing and walking upright.
Morgan states early in her book that the savanna hypothesis for the beginnings of tool use (throwing rocks for defense) would not work because a rock would only be picked up if it happens to be there, in the field-of-view, when needed. Furthermore, it takes practice to throw accurately enough to hit your target. The first time an ape throws a rock, he (her choice of gender) will miss and think that there is no point in doing that again (negative feedback/reinforcement). Without immediate success the behavior would not be repeated, the ape would never experiment and practice enough to discover the benefits, the potential of using tools(experimenting is a lot of failures, negative feedback). The savanna hypothesis does not explain the evolution of tool using behavior.
Towards the end of the book, Morgan describes how she (her choice of gender) invented containers, clay pots to be exact. (personally, I believe that there is a very high likelihood that it was a female that invented the container, a skin bag, I have no problem with her choice of gender.) It seems Ms. Naked Ape got tired of carrying seeds, nuts, tubers, etc. back to camp a few small handfuls at a time. Then one day down at the waterhole she noticed hoof prints in the dried mud and how they held water. In a flash of inspiration, she realized that they could hold seeds and if she could dig the dried print up, she could carry it about, holding the seeds, etc. After several failed attempts because the dried mud broke (negative feedback) she gave up on that. She decided instead to make her own “footprint” that wasn’t part of the ground. She experimented with mud of various consistencies and dried in the sun (probably for varying lengths of time) to make containers. Eventually she succeeded, in spite of all the negative feedback which defeated the concept of throwing rocks (and the fragility of sun-dried mud). Every reason she gives for why the savanna hypothesis’s explanation for the start of tool use is not valid, applies at least as strongly in this case. She contradicts herself.
When I saw the documentary on Morgan’s AAH, I thought that the producers had probably summarized some of the major points of the theory, simplified it all to fit into the hour length of the show. The vagueness of details and the lack of good supporting data, I assumed was the product of fitting the book into the medium of a TV show, and the book would be much more detailed, with more supporting facts. I was both right and wrong. The documentary was a very sympathetic presentation of the AAH. Too sympathetic in a way, the producers left out the more senseless parts, like the invention of pottery or language, and added a new fact or two, like the Danakil Depression originally having been underwater, implying that this is where the aquatic ape lived.
However, the vagueness of details and lack of supporting data was not solely a result of condensing the book to a one hour TV documentary for the general public. The examples used in the show are the same ones, the only ones, presented in the book. The book itself is a bit vague,simple, and lacking in good supporting data. The book was rather clear about when we were supposedly aquatic. It was in the 10 million year long Pliocene, after the end of the Miocene and before the Pleistocene and the australopithecines. And we were marine animals not riverine, lacustrine, or esturine.
The show was wise to skim over the details of when, we have new dates on the Miocene, Pliocene, and Pleistocene, and on the australopithecines. The Miocene ended about 5mya (million year ago) and Pleistocene began by 2mya, if not 2.5mya. The Pliocene was no more than 3 million years long and we have australopithecine fossil as old as 4.2my and a probable ancestor 5my old or more. By the way, the older fossils have been found even further from any ocean, deeper in the sub-Saharan savanna. Morgan cannot be held at fault for these changes in dates and the finding of more fossils. As a good scientist she would take these new facts into consideration and correct her theory as needed. She just ignores these, this is not science.
One last comment: the ocean was not a safe refuge from a predators. It may true that leopards will not go into the water, but they (and lions, hyenas, and jackals) will patrol the shore for whatever they can eat. Sharks will come into shallow water at least occasionally for prey. But there is a far more dangerous and common predator that nobody has mentioned: Crocodylus niloticus. The Nile crocodile lives (or did live) in all of Africa’s rivers south of the Sahara and can live along the coasts. They still kill hundreds of humans every year, hundreds of terrestrial humans.
FURTHER NOTES ON AAH
I was searching the internet a while back, checking on a few details, I typed in “aquatic ape” and discovered that there is a lot of “stuff” on the Internet, both pro and con. I used the word “stuff” because it is a varied collection of uncertain quality. Mostly I was trying to determine if Elaine Morgan was still alive. I didn’t find anything beyond she was born in 1920. I did discover that she seems to have an active band of supporters who continue to argue and promote her hypothesis. Based on what I saw on the internet they are somewhat confused about several important points of the AAH.
1) Aquatic seems to mean “marine” (Morgan definitely meant this). Their examples are from cetaceans (whales and dolphins which are committed to a marine life) and unlike seals which are marine mammals that are partially dependent on the land (semi-aquatic). They all deny that we were anything more than semi-aquatic (so seals and sea lions might be better examples than cetaceans) although we were not a semi-aquatic as seals but more like littoral beachcombers. Perhaps they ignore the other semi-aquatic mammals (both marine: furred seals, sea otters, and freshwater: otters, muskrats, nutria, beaver) because they have fur which provides multiple examples of aquatic mammals that do not have naked skins.
2) Just when this “aquatic phase” happened is unclear. Morgan said it was during the 10 million years of the “torrid” Pliocene. New research and dates have reduced the extent of the Pliocene and reduced the size of the “gap” between the separation of hominines and chimpanzees. So now it must be during the Miocene and it was rising sea levels flooding East Africa and not hot and arid conditions that drove us to the ocean. But there seems to another line of thought—that it was during Homo erectus times, about 150,000 years or so ago. Homo erectus was already a bipedal, medium-brained, tool-user and not a small-brained non-bipedal ape. Jonathan Kingdom thinks that late H. erectus, and early H. sapiens populated the Old World by spreading along the coastlines about 250,000-200,000 years ago. He’s talking about a littoral beach combing adaptation and how we used that cultural adaptation to spread around the world, not as a driving force in our evolution.
3) AAH is why we evolved from quadrupedal, small-brained, furry apes into a bipedal, naked, large-brained humans. If the aquatic phase was during the Miocene why are the Pliocene australopithecines bipedal, slightly larger-brained apes, with or without fur? If during H. erectus times why are they already a bipedal, largish-brained hominine? Bipedalism precedes large brains by maybe 5-6 million years and an enlarged brain precedes the aquatic phase. This is not how evolution works.
Among the “stuff” I found on the internet was an article by Captain Paul Watson entitled The Aquatic Ape, originally published in Ocean Realm in the spring 2001 issue (#4). In the article Captain Watson argues in favor of the AAH. Unfortunately his arguments are in error. What follows are my comments on his article.
On the first page he comments that men have more hair than women. If we lost our hair because men were running after prey hunting, and women were gatherers then men should have less hair than women. (He also points out that grassy plains (the savanna) predators have thick fur and walk on four legs. I guess he is implying that men should have thick fur and run on four legs?) Plains predators mostly hunt at night when their fur is not such a liability (they over-heat rapidly in the heat when exerting themselves.) Men have more hair than women because men have more testosterone. Loss of hair is not to prevent over-heating, it is to make cooling by sweating efficient. Hominines became bipedal to travel efficiently from place to place, not run fast, so both males and females had the same heat-stress. Predators walk and run on four legs because they are descended from four-legged ancestors. The human ancestors were semi-brachiators whose limbs were not specialized for quadrupedal locomotion and they were prone to being semi-erect.
(p.2) Philip Tobias was right, the australopithecines did not evolve on the savannas but in woodlands. The large brain did not really begin to develop until Homo erectus around 1 million years ago and only become a really large brain about 500,000 years ago, not the implied 4-6 million years ago.
Much of East Africa was not inundated. The only great salt water estuary I know of in East Africa is the Rufigi and Niger deltas, although in the rest of Africa there is possibly the Senegal, Zambezi, and Nile. Possibly by jungle swamp he means mangrove swamp which is a better place for arboreal animals than a terrestrial animal, especially one that balances on two legs.
Apomorphies are unique, derived traits, so of course we don’t share them with other apes (they are what separate us from them). This is a term from cladistics and refers to traits that (the shared ones) are because of a continuous genetic link. If there is no genetic link (shared because of a common descent) the traits are homologies. And just because we “share” a trait with some mostly unrelated species does not mean we share a similar cause for the existence of that trait. Most land animals doesn’t matter, only the ones we are closely related to.
Hairless-ness is a trait that has developed in tropical, subtropical, temperate, subarctic, and arctic marine mammals. Elephants do not spend a great deal of time in water and desert elephants certainly don’t. Moose spend time in the water and they have fur. Physics is against the trunk as a snorkel (years ago I experimented with using a garden hose to breathe through while sitting at the bottom of a pool. It was only 8 feet and already the difference between the air pressure and the weight of the water made it impossible for me to expand my lungs. A few years later I took scuba diving lessons and learned the the air in the tanks was adjusted by the regulator to match the pressure of the water so it was possible to breathe).
Bonobos are very arboreal, they do not spend much time in water. They may live in a watery habitat (rain forest with lots of waterways) but that is not the same as showing that their traits exist because of living in water. Proboscis monkeys do live in mangrove swamps and I don’t know that their legs are any longer than their arms, which is typical of arboreal primates. Four longer legs would work as good as two long legs in water, maybe even better. It doesn’t matter how deep you can wade you still need to reach the bottom with your arms (or like moose use your head).
We bipeds may be slower than four-legged mammals (although bipedal ostriches, and rheas are fast, so two legs is not a limiting factor). We are faster than chimps, more energy efficient, and have greater endurance. Bipedalism evolved for reasons other than running. Even zebras and other fast-running plains/savanna animals walk most of their lives.
Maybe human babies can swim from birth. I doubt that a day-old baby can swim alongside of its mother or hold her hair or wet breast. What is the point any how, seals do not give birth in water and their infants don’t go into the water for quite a while. Only cetaceans and other fully aquatic mammals who are committed to life in the water give birth to infants that can swim. Once again they use aquatic mammals as a model when semi-aquatic mammals (like we supposedly were) are different.
Fat is a characteristic of mammals. If terrestrial mammals do not have fat next to the skin it cannot adhere to the skin. Maybe we cannot “twitch” our skin to get rid of insects (do other primates?) but we can erect our hair (piloerection—known as is goosebumps). No other terrestrial animal has exchanged fur for fat.
Only if fresh water is readily available at all times. Actually, not at all times but at least at dependable intervals. An animal adapted to humid tropical forest could be wasteful of water. Salt water is not usable. Sebum is waterproofing for the skin not to keep water out but to keep it in, and in hot environments. Besides haven’t you ever noticed how wrinkly your fingers become if they and you are in water for an extended period of time? You are dehydrating, losing water, something an aquatic mammals doesn’t do. We lose a lot of water through our skin because that is how we keep from over-heating in ho,t dry environments, like the sunny and arid savanna.
The nipple is only accessible when a woman is in water no deeper than the nipple, it doesn’t float upward. The breast should be long and thin with an enlarged “bulb” at the nipple for greater accessibility in water.
The “dive reflex” is an interesting phenomena. I am glad that they mentioned that both aquatic and semi-aquatic animals have it. But they do not show that the reflex is identical in both aquatic, semi-aquatic animals, and humans and not some similar but different response. They do not show that it is only limited to those aquatic and semi-aquatic animals, if it is that widespread among aquatic and semi-aquatic animals perhaps it is a trait of most or all animals or mammals.
No other primate would choose to dive, a lot of humans don’t either. The “ex-aquatic pig” is a statement based on the hairless-ness of modern breeds, and is based on some unnamed “authority.”
We may depend on complex vocalizations like the fully aquatic whales and dolphins (but not the semi-aquatic seals, etc.) but the does not mean we evolved vocalizations for the same reasons. Besides they conflate vocalization with language, they are not identical. Cetaceans use their vocalizations primarily for echo-location like bats, maybe we and they had an aerial phase. Anyway cetacean vocalizations are not made using their mouth, tongue, throat, larynx, and lungs (as humans do). Humans could only make sounds under water with their vocal tract full of water, but then we would drown.
As for the descended larynx, Neandertals may not have had one (according to Liebermann) and the earlier members of Homo and the australopithecines didn’t, which they should have if we evolved a descended larynx millions of years ago. Infants do not have a descended larynx and therefore can safely nurse and breathe at the same time. They can also breathe quite ably through their mouths as any one who has heard a crying baby can testify. Pronghorn antelope open their mouths and extend their tongue when they run, this expands the diameter of the throat and allows the maximum amount of air to enter. They may or may not have a descended larynx but they do breathe through their mouths and they are not aquatic and do not dive. The descended larynx puts adult humans at risk for choking to death.
I have watched moose feed with their heads underwater for extended periods of time (also I have watched elk do this). I guess they breathe under water as they cannot control their breathing. And I have seen video (in the BBC’s Planet Earth series) of crab-eating macaques (Macaca fascicularis) swimming and diving underwater, even swimming along the bottom of more than head deep water searching for food and putting it in their mouths when they find something, all underwater. This was specifically a population living in the mangrove swamps of the Sundabarans so it may not be representative of the species as a whole. However, since the AAH claims that humans are the only mammal that can control their breathing, these macaques must be drowning. Furthermore, the AAH postulates that humans became bipedal to be able to search deeper water for food without putting their noses underwater (as they could not control their breathing (#5)).
Humans do not have teeth like plains predators and it is funny that he uses “baboon like canines” as an example of what kind of teeth predators have. Baboons are omnivores (like humans) and, except for those canines, their teeth are much more human-like than that of predators. Humans are also omnivores so our teeth are adapted for eating various foods. Predators are much more strictly carnivores and their teeth are adapted to slicing meat. We use tools for that. Our teeth and jaws are relatively weak because we use tools for much of what the earlier hominines used their jaws and teeth for. Human teeth look more like pig teeth, another omnivore. Once again their dating is off, the aquatic phase must have been recent and not millions or even several hundred thousand years ago.
He brings up getting freshwater from raw fish, enough “to support a hominid for long periods without access to fresh water.” He provides no data as to how much but I am glad he at least recognizes that an aquatic life may mean fresh water is in short supply.
All the paddles I have had for canoeing and kayaking are elongated, more like chimpanzee hands than human. Kayak paddles for deep water use are very long and narrow. I still do not see any real “webbing” between my fingers. What little skin there is may just be a factor of a convenient way to build skin there (and example of Gould and Lewontin’s spandrels).
There is a lot of doubt that we are a swimming ape. The hair follicles allow sweat to run off fairly well. I do have a question, it sounds like the hair on chimpanzees must point upward if the hair is to resist the flow of water that has been poured on the chimp’s head. The nose is not ideally suited for submergence, if it was, then why do so many children and adults hold their noses. There have been any number of times I have gotten water up my nose and water in the sinus cavity is no fun and can lead to infection. It may be quite easy to equalize pressure by holding the nose and breathing against the stoppage. I have done a number of times, when I have been flying. So I suspect this ability is more of a accidental result, especially as the sinuses are good at humidifying and warming dry and/or cold air. Seems an aquatic ape would not need this ability. The ability of children to close the nose is new to me (wasn’t it argued several times above that hominines had to became bipedal because they couldn’t close their nose like aquatic mammals and would drown?). Furthermore that this ability is lost as they grow up because humans no longer need it, sounds Lamarckian to me.
The AAH has a number of traits that are not particularly useful that we still have and others that would be useful that are gone. It is convenient for AAH and no reason is offered as to why some are still around and others not.
I have tried to find S. C. Cunnane 1999 to find out what it does say. I did find a number of articles criticizing Cunnane. When I first read “that the overall development of brains size has actually decreased in mammals and primates evolving on African savanna ecosystems” I thought it meant that the brains had actually decreased in size. As I thought about it I realized that it might mean no more than the increase in size over time had decreased, that is the brains were not evolving larger as fast as before. His is a different meaning and there is no explanation of what is meant. DHA (docosahexanoic acid) is essential and our bodies can synthesize it. At least one of the critical articles pointed out the it was Lamarckian to believe that brains would grow larger just because the nutrients were more readily available (just because you live along the sea shore doesn’t mean you can actually catch lots of fish without nets or other fishing gear). Besides if your brains require all those nutrients that are in such short supply in terrestrial environments then why does the brain continue to be large and grow larger when you expand into those environments? If our brains grew larger simply because there were more nutrients, why do we not all grow to seven feet or more and be basketball players? Much of the developed world have far more than enough nutrients and calories to grow taller, instead we just get fat. Without the genetic potential and the selective pressure to grow larger brains you will not. Yes, the largest brains (by volume) do exist in the ocean (the aquatic mammals, not the semi-aquatic mammals), the largest animals in existence live in the oceans so therefore that is where the largest brains are. Largest does not necessarily equal highly developed. The most highly developed brains are among the primates and although whales may have very large brains, in relation to the size of the body it is not particularly large. And why do fish who live in these nutrient rich waters have such poorly developed brains?
The foot is not ideally fitted for walking on mud and sand, at least no better than it is for walking on dry land, climbing trees and cliffs. If the foot is so ideal why do not semi-aquatic mammals have a human like foot or even those that just live in swamps, marshes, or other places with soft substrates?
The shore is not a safe place and’ liking the beach” because we lived there many years ago is more of a “racial memory” concept, which has been discredited. Besides, psychologists have found that wide open, partially wooded scenes ( more savanna-like) are more attractive to humans. If sushi is an aquatic hold-over why did only the Japanese retain it, and why is steak tartare popular? Sandy beaches may be nice to spend time on, however the offshore environment is not particularly rich. It is those rocky coast with tide pools and a hard non-shifting substrate that are really rich marine environments.
The interesting fact about the fossil record is that although it is sparse until about 1.5 million years ago, there are some fossils. We diverged from the other apes about 6-7 million years ago and there are some fossils from after that period and plenty in the 2-3 million years before 1.5 million years ago. Morgan said the aquatic phase was in the Miocene 10 million years ago and now it is moved up to 2 million years ago. If East Africa was mostly inundated during the Miocene and early Pliocene then the place to look is inland where the water has since receded. Which is exactly where paleoanthropologists are looking and finding fossils. If the aquatic phase was only some two million years ago (make up your mind) and in areas underwater now, then perhaps it is during the Ice Ages when the oceans were lower, but not so low that the fossils are deep beneath the sea. The fossils would be in the near-shore deposits on the continental shelf in less than several hundred feet of water.
As a scientific hypothesis AAH fails miserably. It predicts that bipedalism, the large brain, loss of the tail, a depend infancy, hairless-ness, protuberant nose, pottery, descended larynx, and some other traits all evolved at the same time and for the same reason. Further it also predicts that fossils from this transition period will be found in beach and shallow water marine deposits of the Miocene, Pliocene, or even the Pleistocene age. The fossils that have been found (from terrestrial environments) document the evolution of these traits (those that leave fossil evidence) separately over a period of five or more million years. Apes lost their tails more than 30mya, bipedalism evolved about 6mya, the large brain began to evolve within the last million years, and pottery is only ten thousand or less years old. Speech and hairless-ness do not leave direct fossil evidence, however full language capability may be 150,000 years old or even less. So AAH fails in these predictions. AAH is not consistent within itself. The timing of the aquatic phase alone is variable and contradictory. It fails to cohere with other areas of the hypothesis and with external scientific evidence. The only research that it has influenced is that of its critics. Supporters seem to spend their time defending the same old “evidence” rather than doing any new research.
AAH is little more than an idea supported by a number of traits that modern humans supposedly have, derived from a phase semi-aquatic life by reason of somebody saying so. Morgan took an idea and collected a mixed bag of stuff to support it, ignoring both logic and contrary evidence.
1) Elaine Morgan 1972, Stein and Day, New York.
2) Apes have lost their tails also but apparently so for other reason altogether. Morgan ignores the fact that living apes and hominines are descended from apes that had lost their tails millions of years before,
3) This is an example of an ad hoc explanation. Rhinos and elephants returned to the land and no longer needed fat for insulation, so they lost it. When humans returned to land and no longer needed the insulating fat, we kept it.
4) The web site URL is: http://www.seashepherd.org/ocean_realm/ocean_realm_spr01.html
5) Does anyone else notice that this contradicts the previous claim that humans are the only mammal that can control their breathing. This is not the only contradiction of the AAH