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AGAINST THE CURRENT
The Aquatic
Ape
By Captain Paul Watson
Sometimes scientific beliefs
can be as rigidly dogmatic as religious beliefs. For the inquiring
scientist who dares to challenge the "facts," the punishment
is usually ridicule, and the deterrent is usually pressure to
desist, or else one's career might suffer as a consequence.
One piece of scientific dogmas
that has troubled me for years is the premise that modern humans
descended from some savanna-hunting ape. I remember questioning
this in an undergraduate anthropology class, only to have the
professor silence me with that "don't be ridiculous"
look.
The savanna hypothesis holds
that humans left the trees and strode out upon the plains. WE
became bipedal because we stood up like meerkats to peruse the
horizon in search of prey. We lost our body hair as a means of
regulating temperature because we began to run in pursuit of
our prey under the open sun. We developed our large brains as
a result of hunting in packs on the plains.
It just never seemed to click.
The same theory holds that man was the hunter, and woman the
gatherer, yet if body hair was lost due to running after prey,
then why do women have even less body hair than men? Why do all
other grassy plains predators have thick body hair and walk on
four legs?
Recent evident has cast even
greater doubts on the savanna theory. It appears that the conditions
that created the great African grasslands did not occur until
after our ancestors had already evolved to walk upright.
In 1995, South African paleontologist
Phillip Tobias delivered a lecture at the University of London
. He reported that foot bones found in Sterkfontein , South Africa
, Demonstrated an "arboreal element" in the environment
of the hominids whose fossils were found there. He concluded
that Australopithecines were not plains dwellers at all. New
findings of fossil animals, plants, and pollen indicate that
the large brain was already well developed before any hominid
set foot on the savanna. Molecular dating places the hominid/chimpanzee
split somewhere between four and six million years ago.
The climate at this time was
warm. Much of East Africa was inundated by a sea-level rise at
the end of the Miocene period and the beginning of the Pliocene.
This meant that much of the jungle was literally swamped, similar
to the great salt estuaries of modern-day East Africa . The early
hominid ancestors did not go to the water. The water came to
them. AS a result, hominids, after the split with the chimp,
literally returned to the sea.
Marine biologist Alistair Hardy
first gave voice to this theory in 960. He called it the Aquatic
Ape hypothesis. Hardy noticed that modern humans shared certain
characteristics with marine mammals that we did not share with
other primates.
Unfortunately, Hardy was advised
by his academic colleagues not to pursue the theory for fear
of damaging his career. Until recently, a very lonely Elaine
Morgan, the author of The Descent of Woman, championed the theory.
Since she gave a presentation at the 1968 Dual Congress on Paleontology
and Human Biology, there has been more attention given to the
idea, especially in the light of the emerging data refuting the
once sacred savanna theory of human development.
The Aquatic Ape theory postulates
that during a period of a million or two years after hominids
broke away from chimpanzees, human ancestors spent a considerable
time living and evolving in estuaries, marshy jungles and along
coastal shorelines.
We share 99 percent of our DNA
with the chimpanzee and we share many pliesiomorphies with chimps
and other primates, the shared characteristics of species with
a common ancestor. An example is that both chimps and humans
have four fingers and an opposable thumb.
Apomorphies are the characteristics
that separate us from our cousins. An example of this is our
relative hairlessness. The fascinating thing is that most of
our apomorphic characteristics are shared with marine mammals.
There are physiological traits that humans and dolphins share
that chimps, monkeys and gorillas do not. In fact, these characteristics
are completely lacking in most land mammals.
How is it that humans can have
these traits yet all other primates and most other land mammals
do not? Looking at the human body and comparing it to a chimpanzee,
we quite readily see both the similarities and the differences.
Looking at a human body and comparing it to a seal or a dolphin,
we can see the similarities that we share with both the chimps
and the dolphins that differentiate the species Homo sapiens
from the other primates.
Hairlessness is a characteristics
shared by humans, dolphins, whales, manatees, and hippos. All
are mammals, and all have hair that is extremely sparse compared
to land mammals. Perceived hairlessness is a trait that has developed
in tropical and subtropical marine mammal species. Elephants
spend a great deal of time in the water, and there is evidence
suggesting that ancestors of today's modern elephants were even
more aquatic-oriented, and that the trunk may have first evolved
as a snorkel.
If we look at the characteristics
that we share with dolphins and do not share with chimpanzees,
we find conscious breath control, greatly reduced body hair,
subcutaneous body fat, and greater brain size and complexity.
Dolphins, however, became fully
aquatic, whereas humans evolved to be semi aquatic.
The ability to walk upright carries
great advantages in a watery environment. Two legs allow for
the primate to wade into deeper water than four legs, thus expanding
forage range. Over time, wading, swimming, and diving would greatly
expand the range of food sources. It is interesting that the
Bonobo and the Proboscis monkeys have longer legs than chimps
and other monkeys respectively, and both these species do spend
time in watery habitats.
Bipedalism on the grasslands
would have slowed the species down, as species that run on four
legs are much faster than species that run on two. Only an aquatic
or arboreal-aquatic lifestyles would give a two-legged primate
an advantage.
Probably the best way to examine
this theory is to ask what specific features an aquatic animals
would be expected to have. The next question would be: do we
have these features?
Strangely, we actually have more
hair follicles than our cousin, the chimpanzee. The difference
is that human hair is very fine and short, giving us a hairless
appearance. What we do have is ten times more adipocytes (fat
cells) than the chimp.
Human babies are born fat, whereas
all other primate babies are born lean. Human babies can swim
from the moment of birth. Other primate babies cannot. Human
babies not only float but also, after being born submerged, can
swim under their own power, holding their breath until reaching
the surface. In the water, the human baby is not helpless. From
the moment of birth on, the human baby can swim alongside its
mother.
Fat is a characteristic of marine
mammals. It encourages buoyancy. It is an excellent insulator
in the water. No other primates have it all over their bodies.
The fat on aquatic mammals adheres to the skin, whereas on terrestrial
animals it is attached to the muscle. In humans it is attached
to the skin.
Human beings do not have a layer
of cutaneous muscle. This layer of "panniculus carnosus"
is found in most terrestrial mammals, including every primate
except ourselves. This is the muscle that allows for twitching
of the skin and thus allows for the twitching away of insects.
No other terrestrial animal has
ever exchanged fur or thick hair for body fat as a form of thermoregulation.
Rhinos, pigs, elephants and hippos all have done so, and all
have been aquatic. One other group that does accumulate great
amounts of fat, although retaining fur, is the hibernators like
the bears. Humans are not hibernators and thus our accumulation
of body fat can only be aquatic.
Another difference is that compared
to all other primates, humans are notorious for wasting water.
We sweat and lose great amounts of salt and water, and we expel
urine much more frequently than other primates do. This kind
of waste makes sense only if water is readily available to the
species at all times. Add to this the fact that humans have more
and larger sebaceous glands than any other primate. The role
of sebum is simply to waterproof the hair and skin.
When swimming, the aquatic apes
would have kept one part of their anatomy above the water more
than any other part, and that of course is the head. Thus hair
remained on the head to insulate the body by preventing heat
loss and preventing sunstroke. L But hair also had another functional
use. We are the only primate whose head hair grows to great lengths.
In the water, without fur to cling to, a baby hominid needed
to cling to something, and long hair provides the most practical
way for the child to attach itself to the parent. It is well-researched
that women's hair grows faster and thicker during pregnancy.
The development of the human
female breast can also be explained by this theory. A female
breast is primarily fat, and fat floats, thus the child in the
water would have access to the nipple at the surface.
The most fascinating aspect of
this theory however is the fact that humans possess the "diving
reflex." The diving reflex, or bradycardia, is a condition
that occurs in aquatic and semi aquatic animals. It involves
a decrease in the heart rate and the redistribution of blood
to the brain and the oranges. This process is called vasoconstriction.
This ability is natural in humans. Blow on a baby's face and
submerge the baby and the baby will hold its breath until it
resurfaces. This ability is both voluntary and involuntary. When
we choose to dives, we can hold our breath for up to two minutes,
and with training up to seven minutes. Humans can dive to depths
of one hundred meters at the extreme, but most humans in fair
health can certainly dive to ten meters. No other primate would
choose to do this.
In involuntary situations, especially
in colder waters, the body can shut down, and people have survived
over thirty minutes of submersion without physical or mental
damage. Studies on dolphins, seals, and sea lions demonstrates
that they can willfully hold their breath for long periods, but
when forced to submerge without knowing when they will resurface,
heart rates plummet to as low as eight beats a minute from the
forty of a normal dive, and they can remain submerged for three
to four times as long as they would voluntarily.
It is interesting that the diving
reflex of an ex-aquatic, the pig, when trained to dive is equal
to that of an untrained human being. This ability to hold and
control our breath also led to a skill that we share with marine
mammals and not shared by our primate cousins: the ability to
form complex speech. Although we share the ability to communicate
through body language and facial expressions with other primates,
we depend upon complex vocalization as our primary method of
communication-just as whales and dolphins do.
Complex speech is dependent upon
the ability to hold and control breath. Other primates are unable
to voluntarily hold their breath. Additionally, the more advanced
range of sounds that humans can emit is due to a descended larynx.
In humans, the larynx is deep in the throat, and unlike other
apes, is no longer in contact with the uvula. This allows humans
to take in air not only through the nose but also through the
mouth. The larynx descended so that we could take in air through
our mouths. The ability to take in air through the mouth allowed
us to take deep breaths prior to diving. Thus our ability to
speak the way we do is a direct result of adaptations meant for
diving. A descended larynx is not found in other primates, but
it is found in sea lions, walrus, and in manatees.
Let's look at our teeth. If we
were predators on the plains, we should have developed baboon
like canines. The fact is we do not have teeth that can tear
and rip animal flesh. Yet our teeth are ideally adapted to eat
practically anything in a marine environment. We can crack crustacean
shells, we can eat live fish raw, and we can chew seaweed. By
chewing raw fish, fresh water can also be extracted, sufficient
to support a hominid for long periods without access to fresh
water. Early Australopithecine teeth most closely resemble those
of the sea otter. Today we possess relatively weak jaws and teeth
suited for softer aquatic foods, more so than rough plant fiber
and animal flesh. I once sat on the bottom in thirty feet of
water and ate oysters. I was able to open them, put them in my
mouth, expel the seawater and swallow them without the use of
any tool or scuba equipment. I think our ancestors may have done
that easily.
Look at our hands-squared compared
to the elongated hands of other primates. More paddle like, and
between the fingers and toes, there is evidence of webbing. Some
people have more than others do. There is no doubt that we are
the swimming ape. We know how to move through water and our bodies
seem to be designed for it. When you pour a pail of water onto
a chimp or a monkey, the hair follicles on the body actually
resist the flow of water, whereas on the human, the hair follicles
flow with the water.
When we pull our heads from the
water, the water streams down and is diverted from the eyes by
our eyebrows. This is a very functional use for this strange
pattern of hair growth. Consider the nose. It also is ideally
suited for submergence in water. Because we have a sinus cavity,
we can equalize pressure simply by holding the nose and breathing
out. Many young children have the ability to completely close
their nostrils at will just like seals and dolphins do. Usually
this ability is lost as the child grows, but quite possibly it
is lost due to the lack of use and is a carry-through of our
once-aquatic past.
Recent research (S. C. Cunnane
1999) has shown that the overall development of brain size has
actually decreased in mammals and primates evolving on African
savanna ecosystems. This has been linked to the deficiency in
the savanna food chain of Docosahexanoic acid. This molecule
is essential for brain growth and is deficient in terrestrial
ecosystems although very abundant in marine ecosystems.
It is not accident that the most
highly developed brains are found in the oceans among the aquatic
and semi aquatic species. The best source of nutrients for a
developing brain is the marine or lake habitats where essential
elements like iodine, zinc, and long=chained fatty acids are
plentiful.
Look at the human foot. It is
an ideal structure for walking on mud and sand.
In a hostile world with jungle
and grasslands literally crawling with predators, what safer
place would there be than the area between the shore and deep-water?
Food is plentiful, the habitat comfortable. We still all love
the beach, many love to swim, enjoy the feeling of mud between
our toes and like sushi. Most importantly, our physiology suggests
that at some point we spent a considerable amount of time in
the water.
How long? It is interesting that
our fossil record is very sparse from that period when we diverged
from the chimps until about a million and a half years ago. This
gives a period of between two and three million years for our
ancestors to have been beach bums. That's plenty of time for
physiological evolution to allow for the adaptation of physical
changes that would allow us to utilize the aquatic environment
more efficiently.
I think the fossils exist. We've
just been looking for them in the wrong places. Look instead
to where the shores of Africa once were, some two million years
ago, places that today are deep beneath the sea. There in the
benthic muck, alongside the fossilized shells and fish bones,
I am of the opinion we could find the skulls and bones of those
water-loving ancestors whose chosen habitat has made us what
we are today-the naked, swimming, dive-reflex-equipped, vocalizing
and intelligent primates that we are.
This article appeared in the
Spring 2001 issue of Ocean Realm magazine and appears
here by permission.
P.O. Box 2616, Friday Harbor,
WA 98250 (USA) Tel: 360-370-5650 Fax: 360-370-5651
Copyright © 2004 Sea Shepherd
Conservation Society. All rights reserved.
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