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The aquatic ape hypothesis (AAH), also referred to as aquatic ape theory (AAT) or the waterside hypothesis of
human evolution Human evolution is the evolutionary process within the history of primates that led to the emergence of '' Homo sapiens'' as a distinct species of the hominid family, which includes the great apes. This process involved the gradual developmen ...
, postulates that the ancestors of modern humans took a divergent evolutionary pathway from the other
great apes The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); ''Gorilla'' (the ...
by becoming adapted to a more aquatic habitat. The hypothesis was initially proposed by the English marine biologist Alister Hardy in 1960, who argued that a branch of apes was forced by competition over terrestrial habitats to hunt for food such as
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environ ...
on the sea shore and sea bed, leading to adaptations that explained distinctive characteristics of modern humans such as functional hairlessness and
bipedalism Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
.
Elaine Morgan Elaine Morgan OBE, FRSL (7 November 1920 – 12 July 2013), was a Welsh writer for television and the author of several books on evolutionary anthropology. She advocated the aquatic ape hypothesis, which she advocated as a corrective to what ...
advanced this hypothesis in her 1972 book '' The Descent of Woman'', contrasting it with
Desmond Morris Desmond John Morris FLS ''hon. caus.'' (born 24 January 1928) is an English zoologist, ethologist and surrealist painter, as well as a popular author in human sociobiology. He is known for his 1967 book ''The Naked Ape'', and for his telev ...
's theories of sexuality, dubbed by her as "male science", and then in detail in her 1990 book ''Scars of Evolution'', which received some favorable reviews but was subject to criticism from the anthropologist John Langdon in 1997, who characterized it as an "umbrella hypothesis" with inconsistencies that were unresolved and a claim to validation via the principle of parsimony that was false. The hypothesis is highly controversial, and has been criticized by many as
pseudoscience Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claim ...
. The hypothesis is thought to be more popular with the lay public than with scientists; in the scientific literature, it is generally ignored by
anthropologist An anthropologist is a person engaged in the practice of anthropology. Anthropology is the study of aspects of humans within past and present societies. Social anthropology, cultural anthropology and philosophical anthropology study the norms an ...
s.


History

In 1942 the German
pathologist Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in th ...
Max Westenhöfer (1871–1957) discussed various human characteristics ( hairlessness,
subcutaneous fat The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and macro ...
, the regression of the olfactory organ, webbed fingers, direction of the
body hair Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androge ...
etc.) that could have derived from an aquatic past, quoting several other authors who had made similar speculations. As he did not believe human beings were
apes Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its sister g ...
, he believed this might have been during the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, contrary to what is possible given the geologic and evolutionary biology evidence available at the time. He stated: "The postulation of an aquatic mode of life during an early stage of human evolution is a tenable hypothesis, for which further inquiry may produce additional supporting evidence." He later abandoned the concept. Independently of Westenhöfer's writings, the marine biologist Alister Hardy had since 1930 also hypothesized that humans may have had ancestors more aquatic than previously imagined, although his work, unlike Westenhöfer's, was rooted in the Darwinian consensus. On the advice of his colleagues, Hardy delayed presenting the hypothesis for approximately thirty years. After he had become a respected academic and knighted for contributions to marine biology, Hardy finally voiced his thoughts in a speech to the British Sub-Aqua Club in
Brighton Brighton () is a seaside resort and one of the two main areas of the City of Brighton and Hove in the county of East Sussex, England. It is located south of London. Archaeological evidence of settlement in the area dates back to the Bronze A ...
on 5 March 1960. Several national newspapers reported sensational presentations of Hardy's ideas, which he countered by explaining them more fully in an article in ''
New Scientist ''New Scientist'' is a magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publish ...
'' on 17 March 1960: "My thesis is that a branch of this primitive ape-stock was forced by competition from life in the trees to feed on the sea-shores and to hunt for food,
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environ ...
, sea-urchins etc., in the shallow waters off the coast." The idea was generally ignored by the
scientific community The scientific community is a diverse network of interacting scientists. It includes many " sub-communities" working on particular scientific fields, and within particular institutions; interdisciplinary and cross-institutional activities are als ...
after the article was published. Some interest was received, notably from the geographer
Carl Sauer Carl Ortwin Sauer (December 24, 1889 – July 18, 1975) was an American geographer. Sauer was a professor of geography at the University of California at Berkeley from 1923 until becoming professor emeritus in 1957. He has been called "the de ...
whose views on the role of the seashore in human evolution "stimulated tremendous progress in the study of coastal and aquatic adaptations" inside
marine archaeology Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...
. In 1967, the hypothesis was mentioned in ''
The Naked Ape ''The Naked Ape: A Zoologist's Study of the Human Animal'' is a 1967 book by English zoologist and ethologist Desmond Morris that looks at humans as a species and compares them to other animals. '' The Human Zoo'', a follow-up book by Morris ...
'', a popular book by the zoologist
Desmond Morris Desmond John Morris FLS ''hon. caus.'' (born 24 January 1928) is an English zoologist, ethologist and surrealist painter, as well as a popular author in human sociobiology. He is known for his 1967 book ''The Naked Ape'', and for his telev ...
, who reduced Hardy's phrase "more aquatic ape-like ancestors" to the bare "aquatic ape", commenting that "despite its most appealing indirect evidence, the aquatic theory lacks solid support". While traditional descriptions of 'savage' existence identified three common sources of sustenance: gathering of fruit and nuts, fishing, and hunting, in the 1950s, the anthropologist
Raymond Dart Raymond Arthur Dart (4 February 1893 – 22 November 1988) was an Australian anatomist and anthropologist, best known for his involvement in the 1924 discovery of the first fossil ever found of ''Australopithecus africanus'', an extinct hom ...
focused on hunting and gathering as the likely organizing concept of human society in prehistory, and hunting was the focus of the
screenwriter A screenplay writer (also called screenwriter, scriptwriter, scribe or scenarist) is a writer who practices the craft of screenwriting, writing screenplays on which mass media, such as films, television programs and video games, are based. ...
Robert Ardrey Robert Ardrey (October 16, 1908 – January 14, 1980) was an American playwright, screenwriter and science writer perhaps best known for ''The Territorial Imperative'' (1966). After a Broadway and Hollywood career, he returned to his academic tr ...
's 1961 best-seller '' African Genesis''. Another screenwriter, Elaine Morgan, responded to this focus in her 1972 ''Descent of Woman'', which parodied the conventional picture of "the Tarzanlike figure of the prehominid who came down from the trees, saw a grassland teeming with game, picked up a weapon and became a Mighty Hunter," and pictured a more peaceful scene of humans by the seashore. She took her lead from a section in Morris's 1967 book which referred to the possibility of an ''Aquatic Ape'' period in evolution, his name for the speculation by the biologist Alister Hardy in 1960. When it aroused no reaction in the academic community, she dropped the feminist criticism and wrote a series of books–''The Aquatic Ape'' (1982), ''The Scars of Evolution'' (1990), ''The Descent of the Child'' (1994), ''The Aquatic Ape Hypothesis'' (1997) and ''The Naked Darwinist'' (2008)–which explored the issues in more detail. Books published on the topic since then have avoided the contentious term ''aquatic'' and used ''waterside'' instead.


The Hardy/Morgan hypothesis

Hardy's hypothesis as outlined in ''
New Scientist ''New Scientist'' is a magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publish ...
'' was: Hardy argued a number of features of modern humans are characteristic of aquatic adaptations. He pointed to humans' lack of body hair as being analogous to the same lack seen in
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
s and
hippopotamus The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two exta ...
es, and noted the layer of
subcutaneous fat The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and macro ...
humans have that Hardy believed other apes lacked, although it has been shown that captive apes with ample access to food have levels of subcutaneous fat similar to humans. Additional features cited by Hardy include the location of the
trachea The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from t ...
in the
throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebrae. It contains the pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the trachea (windpip ...
rather than the nasal cavity, the human propensity for front-facing
copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetra ...
,
tears Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of ...
and eccrine sweating, though these claimed pieces of evidence have alternative evolutionary adaptationist explanations that do not invoke an aquatic context. Hardy additionally posited that
bipedalism Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
evolved first as an aid to wading before becoming the usual means of human locomotion, and
tool use Tool use by animals is a phenomenon in which an animal uses any kind of tool in order to achieve a goal such as acquiring food and water, grooming, defence, communication, recreation or construction. Originally thought to be a skill possessed o ...
evolved out of the use of rocks to crack open
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environ ...
. These last arguments were cited by later proponents of AAH as an inspiration for their research programs. Morgan summed up her take on the hypothesis in 2011:


Reactions

The AAH is generally ignored by anthropologists, although it has a following outside academia and has received celebrity endorsement, for example from
David Attenborough Sir David Frederick Attenborough (; born 8 May 1926) is an English broadcaster, biologist, natural historian and author. He is best known for writing and presenting, in conjunction with the BBC Natural History Unit, the nine natural histo ...
. Academics who have commented on the aquatic ape hypothesis include categorical opponents (generally members of the community of academic
anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of be ...
) who reject almost all of the claims related to the hypothesis. Other academics have argued that the rejection of Hardy and Morgan is partially unfair given that other explanations which suffer from similar problems are not so strongly opposed. A conference devoted to the subject was held at Valkenburg,
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
, in 1987. Its 22 participants included academic proponents and opponents of the hypothesis and several neutral observers headed by the anthropologist Vernon Reynolds of the
University of Oxford , mottoeng = The Lord is my light , established = , endowment = £6.1 billion (including colleges) (2019) , budget = £2.145 billion (2019–20) , chancellor ...
. His summary at the end was:


Critiques

The AAH is not accepted as empirically supported by the scholarly community, and has been met with significant skepticism. The ''
Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' editor and paleontologist Henry Gee has argued that the hypothesis has equivalent merit to
creationism Creationism is the religious belief that nature, and aspects such as the universe, Earth, life, and humans, originated with supernatural acts of divine creation. Gunn 2004, p. 9, "The ''Concise Oxford Dictionary'' says that creationism is 't ...
, and should be similarly dismissed. In a 1997 critique, anthropologist John Langdon considered the AAH under the heading of an "umbrella hypothesis" and argued that the difficulty of ever disproving such a thing meant that although the idea has the appearance of being a parsimonious explanation, it actually was no more powerful an explanation than the
null hypothesis In scientific research, the null hypothesis (often denoted ''H''0) is the claim that no difference or relationship exists between two sets of data or variables being analyzed. The null hypothesis is that any experimentally observed difference is ...
that human evolution is not particularly guided by interaction with bodies of water. Langdon argued that however popular the idea was with the public, the "umbrella" nature of the idea means that it cannot serve as a proper
scientific hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obser ...
. Langdon also objected to Morgan's blanket opposition to the " savannah hypothesis" which he took to be the "collective discipline of paleoanthropology". He observed that some anthropologists had regarded the idea as not worth the trouble of a rebuttal. In addition, the evidence cited by AAH proponents mostly concerned developments in
soft tissue Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ...
anatomy and physiology, whilst paleoanthropologists rarely speculated on evolutionary development of anatomy beyond the musculoskeletal system and brain size as revealed in fossils. After a brief description of the issues under 26 different headings, he produced a summary critique of these with mainly negative judgments. His main conclusion was that the AAH was unlikely ever to be disproved on the basis of comparative anatomy, and that the one body of data that could potentially disprove it was the fossil record. Anthropologist John D. Hawks wrote that it is fair to categorize the AAH as
pseudoscience Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claim ...
because of the social factors that inform it, particularly the personality-led nature of the hypothesis and the unscientific approach of its adherents. Physical anthropologist Eugenie Scott has described the aquatic ape hypothesis as an instance of "crank anthropology" akin to other pseudoscientific ideas in anthropology such as alien-human interbreeding and
Bigfoot Bigfoot, also commonly referred to as Sasquatch, is a purported ape-like creature said to inhabit the forest of North America. Many dubious articles have been offered in attempts to prove the existence of Bigfoot, including anecdotal claims o ...
. In ''The Accidental Species: Misunderstandings of Human Evolution'' (2013), Henry Gee remarked on how a seafood diet can aid in the development of the human brain. He nevertheless criticized the AAH because "it's always a problem identifying features uch as body fat and hairlessnessthat humans have now and inferring that they must have had some adaptive value in the past." Also "it's notoriously hard to infer habits uch as swimmingfrom anatomical structures". Popular support for the AAH has become an embarrassment to some anthropologists, who want to explore the effects of water on human evolution without engaging with the AAH, which they consider "emphasizes adaptations to deep water (or at least underwater) conditions". Foley and Lahr suggest that "to flirt with anything watery in paleoanthropology can be misinterpreted", but argue "there is little doubt that throughout our evolution we have made extensive use of terrestrial habitats adjacent to fresh water, since we are, like many other terrestrial mammals, a heavily water-dependent species." But they allege that "under pressure from the mainstream, AAH supporters tended to flee from the core arguments of Hardy and Morgan towards a more generalized emphasis on fishy things." In "The Waterside Ape", a pair of 2016 BBC Radio documentaries,
David Attenborough Sir David Frederick Attenborough (; born 8 May 1926) is an English broadcaster, biologist, natural historian and author. He is best known for writing and presenting, in conjunction with the BBC Natural History Unit, the nine natural histo ...
discussed what he thought was a "move towards mainstream acceptance" for the AAH in the light of new research findings. He interviewed scientists supportive of the idea, including Kathlyn Stewart and Michael Crawford who had published papers in a special issue of the '' Journal of Human Evolution'' on "The Role of Freshwater and Marine Resources in the Evolution of the Human Diet, Brain and Behavior". Responding to the documentaries in a newspaper article, paleoanthropologist Alice Roberts criticized Attenborough's promotion of AAH and dismissed the idea as a distraction "from the emerging story of human evolution that is more interesting and complex". She argued that AAH had become "a theory of everything" that is simultaneously "too extravagant and too simple". Philosopher
Daniel Dennett Daniel Clement Dennett III (born March 28, 1942) is an American philosopher, writer, and cognitive scientist whose research centers on the philosophy of mind, philosophy of science, and philosophy of biology, particularly as those fields relat ...
, in his discussion of evolutionary philosophy, commented "During the last few years, when I have found myself in the company of distinguished biologists, evolutionary theorists, paleoanthropologists and other experts, I have often asked them to tell me, please, exactly why Elaine Morgan must be wrong about the aquatic theory. I haven’t yet had a reply worth mentioning, aside from those who admit, with a twinkle in their eyes, that they have also wondered the same thing." He challenged both Elaine Morgan and the scientific establishment in that "Both sides are indulging in adapt tonist
Just So stories ''Just So Stories for Little Children'' is a 1902 collection of origin stories by the British author Rudyard Kipling. Considered a classic of children's literature, the book is among Kipling's best known works. Kipling began working on the ...
". Along the same lines, historian Erika Lorraine Milam noted that independent of Morgan's work, certain standard explanations of human development in paleoanthropology have been roundly criticized for lacking evidence, while being based on sexist assumptions. Anatomy lecturer Bruce Charlton gave Morgan's book ''Scars of Evolution'' an enthusiastic review in the
British Medical Journal ''The BMJ'' is a weekly peer-reviewed medical trade journal, published by the trade union the British Medical Association (BMA). ''The BMJ'' has editorial freedom from the BMA. It is one of the world's oldest general medical journals. Origi ...
in 1991, calling it "exceptionally well written" and "a good piece of science". In 1995, paleoanthropologist
Phillip Tobias Phillip Vallentine Tobias (14 October 1925 – 7 June 2012) was a South African palaeoanthropologist and Professor Emeritus at the University of the Witwatersrand in Johannesburg. He was best known for his work at South Africa's hominid fossil ...
declared that the savannah hypothesis was dead, because the open conditions did not exist when humanity's precursors stood upright and that therefore the conclusions of the Valkenburg conference were no longer valid. Tobias praised Morgan's book ''Scars of Evolution'' as a "remarkable book", though he said that he did not agree with all of it. Tobias and his student further criticised the orthodox hypothesis by arguing that the coming out of the forest of man's precursors had been an unexamined assumption of evolution since the days of
Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...
, and followed by Darwin,
Wallace Wallace may refer to: People * Clan Wallace in Scotland * Wallace (given name) * Wallace (surname) * Wallace (footballer, born 1986), full name Wallace Fernando Pereira, Brazilian football left-back * Wallace (footballer, born 1987), full name ...
and
Haeckel Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new s ...
, well before
Raymond Dart Raymond Arthur Dart (4 February 1893 – 22 November 1988) was an Australian anatomist and anthropologist, best known for his involvement in the 1924 discovery of the first fossil ever found of ''Australopithecus africanus'', an extinct hom ...
used it.


Reactions of Hardy and Morgan

Alister Hardy was astonished and mortified in 1960 when the national Sunday papers carried banner headlines "Oxford professor says man a sea ape", causing problems with his Oxford colleagues. As he later said to his ex-pupil
Desmond Morris Desmond John Morris FLS ''hon. caus.'' (born 24 January 1928) is an English zoologist, ethologist and surrealist painter, as well as a popular author in human sociobiology. He is known for his 1967 book ''The Naked Ape'', and for his telev ...
, "Of course I then had to write an article to refute this saying no this is just a guess, a rough hypothesis, this isn't a proven fact. And of course we're not related to
dolphins A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...
." Elaine Morgan's 1972 book ''Descent of Woman'' became an international best-seller, a
Book of the Month Book of the Month (founded 1926) is a United States subscription-based e-commerce service that offers a selection of five to seven new hardcover books each month to its members. Books are selected and endorsed by a panel of judges, and members ch ...
selection in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
and was translated into ten languages. The book was praised for its feminism but
paleoanthropologist Paleoanthropology or paleo-anthropology is a branch of paleontology and anthropology which seeks to understand the early development of anatomically modern humans, a process known as hominization, through the reconstruction of evolutionary kinsh ...
s were disappointed with its promotions of the AAH. Morgan removed the feminist critique and left her AAH ideas intact, publishing the book as ''The Aquatic Ape'' 10 years later, but it did not garner any more positive reaction from scientists.


Related academic and independent research

Although the general reaction to Hardy and Morgan's proposals was silence by the relevant academic community, there have been over the last decades some academics who were inspired by AAH proposals, even to the point of pursuing particular lines of research on its basis. Some of the academics and professional scientists who have supported the AAH include Michael Crawford, Professor and Director of the Institute of Brain Chemistry and Human Nutrition at
Imperial College London Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a cu ...
, his former postdoctoral researcher, Stephen Cunnane, now professor of medicine at Université de Sherbrooke, Erika Schagatay, professor of Environmental Physiology at
Mid Sweden University Mid Sweden University (''Mittuniversitetet'') is a Swedish state university located in the region around the geographical center of Sweden, with two campuses in the cities of Östersund and Sundsvall. The university closed a third campus in H ...
, Kathlyn M. Stewart, Section Head of
Palaeobiology Paleobiology (or palaeobiology) is an interdisciplinary field that combines the methods and findings found in both the earth sciences and the life sciences. Paleobiology is not to be confused with geobiology, which focuses more on the interac ...
at the
Canadian Museum of Nature The Canadian Museum of Nature (french: Musée canadien de la nature; CMN) is a national natural history museum based in Canada's National Capital Region. The museum's exhibitions and public programs are housed in the Victoria Memorial Museum B ...
, and Tom Brenna, Professor of Paediatrics and Chemistry at
University of Texas The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,075 ...
.


Wading and bipedalism

AAH proponent Algis Kuliukas, performed experiments to measure the comparative energy used when lacking
orthograde posture Orthograde is a term derived from Greek ὀρθός, ''orthos'' ("right", "true", "straight") + Latin ''gradi'' (to walk) that describes a manner of walking which is upright, with the independent motion of limbs. Both New and Old World monkeys ...
with using fully upright posture. Although it is harder to walk upright with bent knees on land, this difference gradually diminishes as the depth of water increases and is still practical in thigh-high water. In a critique of the AAH, Henry Gee questioned any link between bipedalism and diet. Gee writes that early humans have been bipedal for 5 million years, but our ancestors' "fondness for seafood" emerged a mere 200,000 years ago.


Diet

Evidence supports aquatic food consumption in ''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely rela ...
'' as early as the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58taphonomic bias is the problem, as most hominin fossils occur in lake-side environments, and the presence of fish remains is therefore not proof of fish consumption. They also claim that the archaeological record of human fishing and coastal settlement is fundamentally deficient due to postglacial
sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...
. In their 1989 book ''The Driving Force: Food, Evolution and The Future'', Michael Crawford and David Marsh claimed that
omega-3 fatty acid Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chem ...
s were vital for the development of the brain: Crawford and Marsh opined that the brain size in aquatic mammals is similar to humans, and that other primates and carnivores lost relative brain capacity. Cunnane, Stewart, Crawford, and colleagues published works arguing a correlation between aquatic diet and human brain evolution in their "shore-based diet scenario", acknowledging the Hardy/Morgan's thesis as a foundation work of their model. As evidence, they describe health problems in landlocked communities, such as
cretinism Congenital iodine deficiency syndrome is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It ...
in the Alps and
goitre A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly. Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
in parts of Africa due to salt-derived iodine deficiency, and state that inland habitats cannot naturally meet human iodide requirements. Biologists Caroline Pond and Dick Colby were highly critical, saying that the work provided "no significant new information that would be of interest to biologists" and that its style was "speculative, theoretical and in many places so imprecise as to be misleading." British palaeontologist Henry Gee, who remarked on how a seafood diet can aid in the development of the human brain, nevertheless criticized AAH because inferring aquatic behavior from body fat and hairlessness patterns is an unjustifiable leap.


Diving behavior and performance

Aside from working as a professor, Erika Schagatay is also an experienced
scuba Scuba may refer to: * Scuba diving ** Scuba set, the equipment used for scuba (Self-Contained Underwater Breathing Apparatus) diving * Scuba, an in-memory database developed by Facebook * Submillimetre Common-User Bolometer Array, either of two in ...
and freediver whose research centers around human diving abilities. She suggests that such abilities are consistent with selective pressure for underwater foraging during human evolution, and discussed other anatomical traits speculated as diving adaptations by Hardy/Morgan. in John Langdon suggested that such traits could be enabled by a human
developmental plasticity Developmental plasticity is a general term referring to changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning. Much like neuroplasticity or brain plasticity, develo ...
.


Vernix caseosa

Tom Brenna, professor of pediatrics whose primary research focuses on fats, oils, and
fatty acids In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an B ...
, listened to the 2005 radio documentary ''Scars of Evolution'' where
David Attenborough Sir David Frederick Attenborough (; born 8 May 1926) is an English broadcaster, biologist, natural historian and author. He is best known for writing and presenting, in conjunction with the BBC Natural History Unit, the nine natural histo ...
reported an observation that
harbor seal The harbor (or harbour) seal (''Phoca vitulina''), also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped (walruses, eared se ...
s were born with something that resembled human
vernix caseosa Vernix caseosa, also known as vernix or birthing custard, is the waxy white substance found coating the skin of newborn human babies. It is produced by dedicated cells and is thought to have some protective roles during fetal development and for ...
. Intrigued, Brenna led a team that collaborated with Judy St Leger at San Diego Seaworld to compare the chemistry of human vernix and samples from
California sea lion The California sea lion (''Zalophus californianus'') is a coastal eared seal native to western North America. It is one of six species of sea lions. Its natural habitat ranges from southeast Alaska to central Mexico, including the Gulf of Ca ...
pups. They established that the molecular composition of both is similar, being rich in branched chain fatty acids and squalene.


See also

*
Aquatic mammal Aquatic and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species, such as the European otter. They ...
*
Diving reflex The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It opt ...
*
Endurance running hypothesis The endurance running hypothesis is a series of conjectures which presume humans evolved anatomical and physiological adaptations to run long distances . and, more strongly, that "running is the only known behavior that would account for the di ...
*
Hunting hypothesis In paleoanthropology, the hunting hypothesis is the hypothesis that human evolution was primarily influenced by the activity of hunting for relatively large and fast animals, and that the activity of hunting distinguished human ancestors from ot ...
* Stoned ape theory * Triune brain


References


Bibliography

* * * * * * * * * * * * * * {{Portal bar, Evolutionary biology, Paleontology 1960 introductions Biological hypotheses Human evolution Aquatic mammals Hypothetical life forms Pseudoscience Fringe science