Taylor Alshuth
ANTH 410
Position Paper: Aquatic Ape Hypothesis
Introduction
Paleoanthropology is a field that is ripe with controversy. No matter how you spin it, the
subject of human origins will always be a controversial one. The field of Paleoanthropology is
has had more than its far share of controversies such as Piltdown man, the savannah
hypothesis, and the ever clashing egos of its top scholars. The most controversial theory of all is
perhaps the Aquatic Ape Hypothesis. The Aquatic Ape Hypothesis (AAH) or Aquatic Ape Theory
(AAT) as it is also known states that many of the most defining human traits such as bipedalism
and our large brains are the result of early human ancestors evolving in a partially aquatic
environment. This is a hot topic in Paleoanthropology mostly because of overwhelmingly
vehement rejection from scientists at the idea that our ape ancestors had any strong
association with an aquatic environment. They argue that it provides too simple or too
convenient of an answer to the question of why these traits evolved and were selected for in
our ape environments. I find the Aquatic Ape Hypothesis fascinating. I think that there is some
merit to it and that it shouldn't be completely disregarded. I will be arguing in favor of the
Aquatic Ape Hypothesis, presenting its claims as well as its shortcomings. I don't intend to
convince you that humans evolved from so-called "aquatic apes", but there are many aspects of
it that I believe have a place in human evolutionary theory.
The claim
So what exactly is the Aquatic Ape Hypothesis? The Aquatic Ape Hypothesis states that
the primary catalyst from the split of the last common ancestor between humans and
chimpanzees was an aquatic environment. It states that many of the defining traits of hominids
are evolutionary remnants of living in partially aquatic environment that weren't selected
against when these early hominids moved onto the savannah. For instance, it states that
bipedalism was an adaptation for wading through water and after these apes left the partially
aquatic environment it provided an advantage for living in the savannah by being able to see
predators in the tall grasses. Our relative hairlessness compared to other primates might have
gotten its start by living in a partially aquatic environment where excess body hair would've
gotten in the way. Humans also have a descended larynx which gives us a lot of control of our
breathing, something that is common in aquatic mammals but almost unseen in terrestrial
mammals. Human fingers also wrinkle when they are submerged in water for long periods of
time. This actually improves human grip when handling wet objects but offers no additional
assistance when handling dry objects. Lastly, one of the trends seen in early hominid evolution
is an increase in brain size. The Aquatic Ape Hypothesis states that this trend could've been
started with the consumption of seafood rich in Omega-3's and other fatty acids. There are
other claims being cited by those in favor of the Aquatic Ape Theory but the ones that I
previously stated are the most popular. Most of these claims have been presented by Elaine
Morgan, a writer who has written many books on the subject of evolutionary anthropology. She
was by far the most vocal supporter of the Aquatic Ape Hypothesis and even wrote a book on
the subject.
Refuting the claim
It's not surprising that the Aquatic Ape Hypothesis is rejected by paleoanthropologists
and mainstream scientists. They state that it provides an all to convenient explanation for all of
the traits that separate hominids from other apes. Instead of them evolving separately as a
result of different environmental pressures, having them all evolve as the result of one specific
environmental condition is a very Lamarckian view of human evolution. They have raised many
points refuting those presented by the Aquatic Ape Hypothesis, such as bipedalism having
already appeared in fossils such as Orrorin tugenensis which is postulated to have lived in a
dense woodland environment rather than a swampy or near-shore environment. The reduction
in body hair probably came about as a response to sweating and other factors. Reduced body
hair means reduced body parasites, another advantage if you are living in an area with
abundant parasites such as the grasslands. The descended larynx is thought to be a result of
adaptations related to vocalizations and ultimately lead to the evolution of human speech
which would explain its absence in other apes. Our large brains are thought to be the result of
eating meat that early hominids would've scavenged off of carcasses left behind by other
predators. They would've broken bones open to consume the marrow which if very nutritious
and would've undoubtedly contributed to early hominid brain development. For each claim
that the Aquatic Ape theory makes there are several ways that science has to refute them.
Many people often put the Aquatic Ape Hypothesis with other branches of pseudoscience,
stating that there is not enough evidence to support most of the claims that they are making
and the evidence that does support their claims are circumstantial at best.
My response
I believe that there is some scientific merit to the claims made by the Aquatic Ape
Hypothesis. There are some aspects of it that I do not believe such as early hominids evolving
near the sea, but I do feel that some of the claims are worth consideration. The strongest
argument in the Aquatic Ape Hypothesis is the one they make about bipedalism. One thing I
don’t see mentioned at all with the savannah model or other models about the origins of
bipedalism is how parts of Africa flood during the rainy season. It doesn't matter if you are on
the open savannah or the dense woodland, if you are in a low lying environment chances are it
will flood to some degree. I believe that bipedalism evolved as a response to various
environmental factors and cannot be hand-waved with just one explanation. If one wants to
see some physical evidence for the Aquatic Ape Hypothesis you need to look no further than
the Proboscis Monkey. This monkey lives in the mangrove swamps of Borneo. It has slightly
webbed hands and feet and it is a rather adept swimmer. They are primarily arboreal but will
descend to the ground to travel or search for food. The same way scientists are looking at
Baboons for an idea of how savannah hominids might have lived we could look at the Proboscis
Monkey to see how partially aquatic apes might have lived. They would've eaten a similar diet
of mostly fruits and leaves with some insects. They spend the vast majority of their time in trees
much like it is believed our early hominid ancestors did. This provides a best of both worlds
scenario. I'm not rejecting the facts that have been presented by Paleoanthropology but am
trying to expand upon them by observing primates that may have lived in a similar
environmental situation. Overall, the Aquatic Ape Hypothesis is hotly debated but some of its
ideas still deserve some merit.