To: All Msg #13, Nov0793 03:42PM Subject: Re: Request for Summary Aquatic Ape Theory Follo
From: Pat Dooley
To: All Msg #13, Nov-07-93 03:42PM
Subject: Re: Request for Summary - Aquatic Ape Theory
Organization: Co-Cam Computer Group, Oz
From: email@example.com (Pat Dooley)
The Aquatic Ape Theory
This is a summary of Elaine Morgan's expositions
with a few additions from other sources. For a proper
introduction, please read her book, "The Scars of Evolution".
Some useful evolutionary principles
1. Convergent Evolution: When two organisms occupy similar
environments, they often evolve similar adaptations. For example,
bats and two cave-living birds have evolved echo-location.
2. Non-disadvantageous intermediates: Evolution will never proceed
from one form to a more advantageous form if the intermediate
form is disadvantageous.
3. Dollo's Law: Evolution is irreversible. That means that if
a particular adaptation appears , it is extremely unlikely
that that adaptation, and that adaptation alone, will disappear.
4. The dirty slate of evolution: This principle simply states
that evolution cannot design a new feature starting with a clean
slate; it can only adapt existing features. For example,
vertebrate eyes are wired back-to front, with the millions of nerves
connecting the photo-receptors to the visual cortex running across the
retina and exiting through the "blind-spot". If the vertebrate eye
had been designed from a clean slate, the nerves would have been
directly connected to the visual cortex. Octopii got it right,
indicating that their eyes evolved independently of vertebrate
eys. (Remember this example next time a myopic creationist tries
to tell you how perfectly God made the human eye).
5. Evolution doesn't progress uniformly: The experts forgot this
one as they described the evolution of man from the ape ancestor,
based on very early ape fossils and quite recent Homo fossils.
They assumed that bipedalism and brain size evolved together at
a fairly uniform rate. Lucy proved that the evolution of bipedalism
was virtually over before the rapid evolution of Homo's brain had
even begun. One still sees popular stage-by-stage representations
of the evolution of Homo sapiens showing an ape slowly growing more
erect, with the head growing larger, the forehead more vertical,
the skin getting progressively less hairy and paler.
History of the Aquatic Ape Theory
The Aquatic Ape Theory (AAT) was initially proposed by Sir Alister
Hardy and (shades of Darwin and Wallace), independently, by Max
Westenhofer, a German professor who published a little-known
book on human evolution in 1942 (bad timing!) that included a
chapter on the aquatic hypothesis.
The AAT was popularised by Elaine Morgan in three books:
1. The Descent of Woman
2. The Aquatic Ape
3. The Scars of Evolution
The Aquatic Ape Theory (AAT) proposes that after separation
from a common ape ancestor, the evolutionary line leading to
Homo sapiens became partially adapted to an aquatic or semi-
aquatic habitat before returning to a terrestrial environment.
How aquatic are humans?
Babies have a vestigial swimming instinct. They can be taught
to swim before they can be taught to walk. They know instinctively
not to breathe under water.
Adults can swim long distances, even in cool water. For example,
in 1987, Lynne Cox swam across the Bering Strait without wet-suit
or layer of lanolin in 4 hours in water ranging from 3 to 7 degrees
Celsius. In 1993, a South Australian helicopter crash survivor swam
10-15km to shore after spending two hours supporting the injured
pilot. He claimed his extra weight helped him survive in the cool
Humans dive well. Diving women in Japan and Korea work four
hours per day diving up to 80' to collect shellfish and seaweed.
The human record is 262' compared to observed depths of 150' for
penguins and 300' for walruses. Duration underwater is as long as
3.5 minutes compared to 4.5 minutes for sea otters and 10 for
walruses. During a dive, the human heart rate drops from 72 to
35 beats/minute compared to a drop from 95 to 20 in sea lions.
Comparable figures for apes and other primates are not yet available.
Humans have conscious control over their breathing, a useful
adaptation for a swimming/diving mammal.
Many human communities exploit marine environments without the
aid of tools or technology (Australian aboriginals, pearl divers,
coastal communities in SE Asia and Papua New Guinea).
Humans seek out and enjoy sea food. Molluscs and crustaceans
are particular favourites.
The AAT attempts to account for the following features that
separate Homo sapiens from the other apes.
1.Bipedalism (i.e. walking upright on two legs without the
assistance of a counterbalancing tail).
The AAT claims that bipedalism evolved when environmental/climatic/
geological changes forced an isolated group of apes to start foraging
in an aquatic environment. The move into the water would lead to
the adoption of wading, followed by swimming and diving.
Evidence from convergent evolution:
Apes and other primates, because of their arboreal existence
are already partially adapted for bipedalism. If a distant ape
relative was forced into water, it would wade bipedally, whereas
a quadruped would swim. We might note that the ancestors of
all fully aquatic mammals were quadrupedal and observe that Proboscis
monkeys, which have adopted a partially aquatic life in their
recent evolutionary history, wade in shallow water and swim
in deeper water. The Oreopithecus, an extinct ape that apparently
lived in marshland, had undergone skeletal changes to its pelvis
that suggest it was bipedal or a swimmer or both.
Note that bipedalism has the advantage of facilitating swimming
No purely terrestrial primate or mammal, let alone savannah
mammal, has evolved 100% bipedalism. The probable reason is
the principle of disadvantageous intermediates; the first nearly
bipedal animal would totter along like a two year old. The AAT
claims that the only environment that would facilitate bipedalism
in a primate is aquatic.
There is a gap in the hominid fossil record from around 7 million
years ago (mya) through to around 4 million years ago. The skeletons
of Australopithecus afarensis, a likely hominid precursor of the
Homo line, shows that bipedalism had fully evolved during that
fossil gap. The evidence for bipedalism has also been preserved
in fossilised footprints. The ecology of the fossil sites suggests
a lush environment rather than the arid savannah.
Lucy, the first nearly complete skeleton of an Australopithecus
afarensis, had feet that were broader and larger than ours,
(35% of leg length instead of 26%). Her gait was described by
Roger Lewin as "not quite as bad as trying to walk on dry land
wearing swimming flippers but in the same direction."
Humans still suffer from the rapid evolution of bipedalism - back
problems, inguinal hernia, varicose veins, blood pressure problems
(complex biomechanical explanation omitted).
Bipedalism is about as efficient as quadrupedalism for walking but
less efficient when running.
The evolution of bipedalism required major skeletal adjustments.
According to Richard Leakey and Roger Lewin (who studiously ignore
the AAT), "the evolutionary shift from quadrupedalism to bipedalism
would have required an extensive remodelling of the ape's bone
and muscle architecture and of the overall proportion in the lower
half of the body. Mechanisms of gait are different, mechanics of
balance are different, functions of major muscles are different.
An entire functional complex had to be transformed for efficient
bipedalism to be possible." cf. "Origins Reconsidered".
Desmond Morris wrote a book called "The Naked Ape" that drew attention
to another feature that separates humans from our closest ape relatives
(apparently the bonobo [pygmy chimpanzee] and chimpanzee).
The AAT observes that hairlessness in mammals is most often associated
with aquatic and semi-aquatic animals, usually combined with a
layer of subcutaneous fat. Humans still retain hair on their heads,
although this is stronger in females than males. Male humans tend to
go bald, whereas females retain their hair. Moreover, female hair grows
thicker and more strongly during pregnancy.
The AAT suggests that head hair was retained as protection against
solar radiation for an animal that waded and swam. It further suggests
that female head hair was favoured to provide something for baby
aquatic apes to hang onto.
The reasons why an aquatic mammal would lose its fur are obvious:
streamlining to enhance swimming and diving ability. Those aquatic
mammals that have retained their fur, because they spend time on
land in colder climates, have extensively modified it for
the aquatic environment. The smaller ones have gone for oily fur,
whereas the larger ones, like seals, have gone for a soft, dense
inner coat capable of trapping tiny air bubbles, and an outer
layer of glossy guard hair.
Evidence from convergent evolution:
The only bald mammal with no aquatic associations is the mole rat,
which lives underground. The hairless or vestigially hairy mammals
include the walrus, dugong, whale, dolphin, hippopotamus, tapir
(marshland), pig (wallowers), elephant, and, surprise, surprise,
Homo sapiens. (The elephant may have had a partially aquatic past.
It is still a good swimmer and wader that gravitates towards water.)
None. Hair doesn't fossilise, so we have no way of knowing whether
hair loss was recent, a long time ago, or gradual over the last
10 million years (say).
Hairlessness has often been claimed, along with sweating, as an
adaptation for life on the African savannah. However, night time
on the savannah is cool (11 degrees Celsius) and damp during the
rainy season. It is also difficult to reconcile subcutaneous
fat, an adaptation to retain body heat, with a cooling mechanism.
Fur provides good protection against solar radiation and cold
savannah nights. Loss thereof appears maladaptive for a woodland
or savannah ape.
3. Subcutaneous fat
Humans are very fat by terrestrial mammalian standards and most
of it is stored just under the skin. In a new-born baby, it
comprises 16% of body weight compared to 3% in a baboon. It
comprises 27% of the body weight of a 16 year old girl. If it falls
below 22% she will either not begin or will cease menstruation,
even if she lost the fat through an athletic regime rather than
ill-health or malnutrition. (Big clue: anything affecting
reproduction is evolutionally significant.)
The fat is stored under the skin, rather than in internal deposits,
so gross obesity is a uniquely human problem; there is nothing,
least of all the flexible skin, to constrain growth.
A survey of 191 mammal species showed humans have 10 times as many
adipocytes as would be expected in a mammal of similar mass. Since,
God knows, we don't need this fat now, it is reasonable to conclude
that it evolved to meet some past environmental need and that we were
probably even fatter in the past.
The AAT claims that a subcutaneous fat layer is an aquatic feature
that provides buoyancy and insulation. It is maladaptive on land
because it impedes the healing of flesh wounds and it costs energy
to grow and carry around.
Evidence from convergent evolution:
A subcutaneous fat layer (blubber) is common in aquatic and wallowing
mammals, where it provides insulation and buoyancy. It was watching a
seal being dissected that first suggested the AAT to Sir Alister
Hardy, back in 1930.
Mammals have two types of moisture producing glands on their skins.
Acropine glands are associated with hair follicles and initially
evolved for scent production. Eccrine glands are normally found
on the pads of paws and exude a small amount of moisture to improve
Apes have eccrine glands on their palms and soles that exude
moisture to improve their grip in an arboreal environment.
Humans still have vestiges of this response; the sweaty palms,
associated today with emotional tension, have more to do with
an arboreal ape's preparation for flight than with human heat
regulation. Apes have almost as many acropine glands but they
don't appear to do be used for anything except scent production
in the armpits and groin. Mammals that do sweat use acropine glands.
The amount of moisture exuded is limited to the amount that will
evaporate, maximising the cooling effect while minimising water
and electrolyte loss.
Man has lost almost all his acropine glands. The few that are
left are restricted to the groin and armpits, where, as in apes,
they do a poor job of producing "attractive" scents.
Humans have co-opted the eccrine glands for sweating. That
adaptation has not yet been perfected. Sweating is slow to start up,
and is wasteful of water and salt. According to William Montagna,
author of "Advanced Views in Primate Biology", "sweating is an enigma
that amounts to a major biological blunder: it depletes the body
not only of water but also of sodium and other essential eloctrolytes
that are carried off with the water".
The AAT claims that, along with most aquatic animals, man lost
most of his acropine glands because scents are ineffective in
water. The eccrine glands were co-opted for salt excretion,
a problem that air-breathing marine animals solve in a variety
of ways. When proto-hominids moved back to a terrestrial existence
and had to cope with severe over heating problems, the usual
evolutionary solution is sweating. Unfortunately, the acropine
glands were no longer available, so the eccrine glands
A non-aquatic theory of human evolution has to explain why the
usual terrestrial mammalian thermal regulation system of fur,
panting, and (optional) acropine sweating was replaced by
hairlessness, subcutaneous fat and profuse, salty eccrine sweating.
No other terrestrial mammal, let alone primate, has evolved such a
system. Even if this system is accepted as an efficient cooling
system, a purely terrestrial explanation of its evolution
probably violates the principle of non-disadvantageous intermediates.
The non-aquatic version of the evolution of sweating also ignores the
principle of the dirty slate. If sweating had steadily evolved
for heat regulation, it would have used acropine glands, as it
did in baboons.
Aquatic and semi-aquatic mammals have often evolved hairlessness
and blubber. The AAT says these evolved first and sweating later.
Humans differ from the other apes in that they have conscious
control over their breathing. The descended larynx, a feature
shared with dugongs and sea lions is unknown amongst terrestrial
mammals. The disadvantage of this arrangement is that the passages
to the lungs and the stomach are no longer separated. Humans
cannot drink and breathe simultaneously (although new born humans
can; the descent occurs after a few months). Swallowing is made
much more complicated by the need to ensure that food and drink
do not accidentally "go down the wrong way".
The AAT claims that the descended larynx assisted the AA in
taking in lots of air quickly, before diving. It also claims that
conscious control over breathing is a necessary adaptation for
an aquatic mammal. It further notes that these evolutionary changes
pre-adapted Homo for speech.
6. Minor items
Vestigial webbing still appears in around 6% of the population. The
flap of skin between thumb and forefinger is absent in other apes.
Humans under emotional stress shed salt tears. Oddly, this event
is often accompanied by a "lump in the throat", an involuntary
muscular contraction that prevents anything entering the stomach.
These unexplained features may be vestiges of a marine past.
Human sexual behaviour is different from other apes. Oestrus, the
usual mammalian method of regulating sex by signalling when the
female has ovulated, has disapeared. The sexual equipment has been
extensively modified, with the rotation of the pelvis bringing
the vaginal opening forward and the penis growing longer to follow
it around. At some point, it lost the race; and the male switched
to face-to-face copulation as the standard method. In contrast to
apes, the vagina is retracted into the body and covered by thick
folds of skin, a common aquatic adaptation.
Location and timing
The AAT notes that there is still a fossil gap from 7-9 mya
through to 4-3.5 mya. It observes that hominid fossils have been
found in the Rift valley, a massive fault line running down East
Africa. It suggests that the aquatic ape moved down from the
inland Sea of Afar when it became too salty to sustain
Paul Mohr, a geologist, summed up the geological evidence
about the Sea of Afar as follows "by the late Miocene (7 mya),
a marine basin had become established over Northern Afar". It
is now a massive depression with deep salt deposits; the Dead Sea is
going the same way. The Danakil Alps are at the Eastern end of
the salt plain and comprised an island in the Sea of Afar. Note that
the Sea of Afar was formed at about the time when DNA dating tells
us that man split off from the apes. Leon P. Lalumiere of the
US Naval Research Laboratory suggested Danakil Island as a
place where a group of Miocene apes might have got marooned.
He notes "that geographic speciation is the almost exclusive
mode of speciation amongst animals". Small populations on
an island can undergo rapid evolution, especially when the
environment is changing rapidly.
This geological evidence provides a location where a group
of miocene apes could have been forced into foraging in
water in isolation from the rest of the original species.
The subsequent evaporation of the Sea of Afar would have opened
up land bridges back into mainland Africa and the increased
salinity would have slowly wiped out the food supply of
the aquatically adapted apes.
We are more different from chimpanzees and gorillas than they
are from each other, yet the DNA evidence says gorillas branched
off earlier than the chimpanzee/human split. A period of island
evolution in a rapidly changing environment would account for
this anomaly. Memo to anti-AAT paleoanthropologists - the
Danakil Alps might still be worth a look.
According to one E-mail AAT objector, a dozen or more Miocene
apes went extinct. Maybe that bears on the next piece of evidence
for island evolution.
The Baboon marker gene is a viral gene sequence closely related
to the RNA genomes of a retrovirus, referred to as "Type C", that is
endogenous to Baboons and harmless to them. Of 23 African ape
and monkey species tested, 100% possessed the Baboon marker gene.
It apparently evolved to provide protection against the Baboon
retrovirus, when, like AIDS, it crossed the species boundary.
It must have devastated primate populations and wiped out any
that couldn't evolve the Baboon marker gene quickly enough. The
wide range of species infected suggest that the virus was air-borne.
Viruses evolve, so that a virulent strain cam emerge and then
fade away again. The odds against the Baboon marker viral
gene sequence not deriving from the Baboon Type C retrovirus are
astronomical. The same DNA sequence independently evolving 23
times? And it did evolve within the last 10 million years or so;
otherwise, Asian primates would have the same sequence.
The Baboon marker gene was absent from the 17 non-African primates
tested, and Homo sapiens. The most reasonable conclusion to draw
is that after our ancestors split off from chimpanzee's
ancestors, they spent a period of evolution outside of Africa,
thus avoiding the Baboon Type C retrovirus when it was attacking
other primate species. One location for that period might be
the Danakil Island.
Answers to common objections
1. The experts think the AAT is a load of bunkum.
Well, any good crackpot theorist can quote the example of
Wegener and his wild theory of continental drift.
The opponents can always quote Velikovsky, but his theories
were soon refuted once scientists and historians
bothered to examine them.
But the experts have not been able to come up with
a theory of human evolution that satisfies Occam's razor as
well as the AAT, let alone refutes the AAT. Often, they violate
the evolutionary principles I noted at the beginning of this post.
At least a few experts have acknowledged that the AAT is
worthy of serious consideration.
2. Some people are afraid of water
Some are afraid of heights, but it doesn't mean our distant
ape ancestors weren't arboreal.
3. The AAT describes the period of evolution leading up to Lucy,
but she was still adapted for arboreal life.
In "Origins Reconsidered" it is noted that Australopithecus
afarensis (A.a.) was still partially adapted for an arboreal life.
That does not disqualify the AAT. Firstly, previous adaptations
do not disappear very quickly unless they are maladaptive in a
new environment. The curved phalanges (fingers) and relatively long
arms of A.a. may have suited an aquatic life style even though
they were evolved for an arboreal existence. The long, curved
phalanges (toes) of A.a., with webbing, may have been natural
flippers. Secondly, the AAT may have evolved in coastal swamps,
as the proboscis monkey is currently doing. When it descends from
a tree, the proboscis monkey has two choices: swim or wade and it
can do both with reasonable facility. They have been filmed walking
bipedally on dry land.
4. Humans have to be taught to swim and dive
By the time it got to birds and mammals, evolution had discovered
that it was often better to invest in learning ability rather than
hard-wired behaviour. Lots of animal behaviour, such as hunting,
killing, foraging, copulating, flying and swimming, has to be taught
or learnt by observation of adult behaviour. Be that as it may, very
young human babies seem to have vestigial swimming instincts, despite
4 million years of post aquatic evolution.
5. But we are no longer aquatic
This objection usually comes from people who have erected the
straw-man of a seal-like ape, fully evolved for an ocean life.
That misrepresents the AAT. Learn about the proboscis monkey,
project its evolution for another million years or so, and then
pull the bathplug on it.
6. The sharks/crocodiles/box jelly fish would have eaten them.
Plenty of other mammal and bird species have made the transition
to an aquatic existence and survived the threats of marine
predators. Sharks kill far fewer people than lightening,
despite the greater propensity for humans to swim in the ocean
compared to staying outdoors during a thunderstorm.
There is no environment, terrestrial or otherwise, which is free
from predators, and any successful species has figured out how to
avoid extinction by predation.
7. Other primates copulate face to face
Bonobos, according to one E-mail AAT objector, also copulate face
to face. So do Orang Utans, although the male's technique would
see him up on rape charges if he was human.
So what. This is an example of evolution working from a dirty slate.
The Aquatic Ape theory predicts (according to me) that:
1. Bonobos, chimpanzees, gorillas and savannah primates, such as
baboons, will prove inferior waders, swimmers and divers to
2. When these other primates are immersed in cold water, they will
lose body heat much more rapidly than Homo sapiens.
3. The diving reflex in the other primates will be much
less pronounced than in humans, if it is present at all.
4. At the annual Apes' buffet luncheon, Homo sapiens will
eat all the sea food while the other apes will go for the salads
5. Fossils showing the evolution of bipedalism will be found
in those parts of NE Africa that were isolated from mainland Africa
between 9 and 4 million years ago.
6. Please E-mail any further predictions to me and I'll include
them in an AAT prediction list.
Pat Dooley trying to summarise the Aquatic Ape Theory
E-Mail Fredric L. Rice / The Skeptic Tank