The aquatic ape hypothesis ( AAH ) is a hypothesis about human evolution, which posits that the ancestors of modern humans spent a period of time adapting to life in a wet environment.

Langdon argued that the AAH is one of many hypotheses attempting to explain human evolution through a single causal mechanism, and that the evolutionary fossil record does not support such a proposal.

AAH is popular among laypeople and has continued support by a minority of scholars.

Various traits that have been proposed to indicate past adaptation to aquatic conditions and the return to land, but generally the evidence provided for the AAH is equally well accounted for by land-based adaptations without needing to posit an aquatic phase of human development.

While most proto-human fossil sites are associated with wet conditions upon the death of the hominin, this is not seen as evidence for the AAH since being buried in waterside sediment is one of the rare situations in which fossilization is likely to occur ; paleontologists are aware of this preservation bias and expect fossils to be located near such sediments.

There is no fossil evidence to support the AAH.

Proponents of the AAH suggest that bipedalism is disadvantageous when comparing humans to medium sized, terrestrial quadrupeds, but the fossil record shows that the evolution of humans from ape ancestors didn't include a period of quadrupedal locomotion.

In addition, the elongated lower limbs of humans, which is explained by AAH proponents as improving swimming speeds, appears only after the evolution of the genus Homo and biomechanical analysis indicates humans are far too poor swimmers to have derived from an ape ancestor that swam, and pre-human apes would face similar problems.

The AAH has been criticized for containing multiple inconsistencies and lacking evidence from the fossil record to support its claims ( Morgan, for instance, failed to discuss any fossils found after 1960 and much of her analysis is by comparing soft tissues between humans and aquatic species ).

White stated that while the theory had the scientific characteristics of explanatory power and public debate, the only reason it has received any actual scholarly attention is due to its public appeal, ultimately concluding the AAH was unscientific.

Others have similarly noted the AAH " is more an exercise in comparative anatomy than a theory supported by data.

There is ultimately only circumstantial evidence to suggest, and no solid evidence to support the AAH.

ScienceBlogs author Greg Laden has described the AAH as a " human evolution theory of everything " that attempts to explain all anatomical and physiological features of humans and is correct in some areas only by chance.

The AAH has received little serious attention or acceptance from mainstream paleoanthropologists, has been met with significant skepticism and is not considered a strong scientific hypothesis.

# The AAH uses negative arguments, pointing to the flaws and gaps in conventional theories ; though the criticisms of mainstream science and theories can be legitimate, the flaws in one theory do not automatically prove a proposed alternative is true.

Al Ain Hospital ( abbr: AAH, also known as Al Jimi Hospital ) is the general hospital delivering health services to all Al-Ain patients regardless of their nationality.

AAH or Aah is a three-letter acronym or word that can refer to:

Parallels made by proponents of the AAH between humans and the proboscis monkey, which shows mainly behavioral adaptations to a water-based habitat, contradicts any claims of anatomical evidence for the hypothesis.

Many species of modern primates demonstrate some sort of aquatic behaviors ( such as swimming, wading or diving ) and use of aquatic environments ( for thermoregulation, display behavior, range, diet and predation ) but many do not display the traits posited by AAH, suggesting the traits posted as evidence for the AAH may facilitate aquatic behavior rather than evolving as a result of it.

Several theoretical problems have been found with the AAH, and some claims made by the AAH have been challenged as having explanations aside from a period of aquatic adaptation.

Proponents of the AAH have claimed that a number of specific features in hominin evolution suggests that water played a role in natural selection, and that specific traits shared by all humans can therefore be understood as adaptations to an aquatic environment.

Evolutionary biologist Carsten Niemitz states that he believes the AAH as expressed by Morgan didn't fulfill the criteria of a theory or a hypothesis, merely listing analogies of features of savannah type mammals on the one hand and of aquatic mammals and man on the other, asking the scientific community for explanations other than a common aquatic ancestor of extant man.

Marc Verhaegen has also challenged the AAH as expressed by Morgan.

The AAH does not appear to have passed the peer review process, and despite Morgan being praised by various scholars, none of her work has appeared in any academic journals of anthropology or related disciplines.

# The AAH as developed by Morgan has a strong feminist component, which particularly appeals to a specific, feminist audience.

* Aarhus Airport ( AAH ), located 39 km northeast of Århus, serves some 540, 000 passengers a year.

AAH emerged from the observation that some traits that set humans apart from other primates have parallels in aquatic mammals.

Morgan's critics have claimed that the appeal of AAH can be explained in several ways:

# The AAH can be explained simply and easily, lacking the myriad details and complicated theorizing involved in dealing with primary sources and materials.

AAH has not been accepted among the mainstream explanations of human evolution.

Despite modifications to the hypothesis and occasional forays into scientific conferences, the AAH has neither been accepted as a mainstream theory nor managed to venture a genuine challenge to orthodox theories of human evolution.

The context of the initial presentations of AAH ( a popular essay and a political text ) diverted attention away from the possible scientific merits of the hypothesis.

Avalon has a number of organizations and activities, including: the Library, the GSA, AAH ( Art After Hours ), the mentor program ( where older students mentor new students ), a peer mediator program, and Tech Committee.

AAH suggests that many features that distinguish humans from their nearest evolutionary relatives emerged because the ancestors of humans underwent a period when they were adapting to an aquatic or semiaquatic way of life, but returned to terrestrial life before having become fully adapted to the aquatic environment.

Morgan has claimed the AAH was rejected for a variety of reasons unrelated to its explanatory power: old academics were protecting their careers, sexism on the part of male researchers, and her status as a non-academic intruding on academic debates.

The company had its origins in the early 1980s when Mike Williams launched Focus Homecentres for AAH Holdings plc.

Few paleoanthropologists have explicitly evaluated AAH in scientific journals, and those that have reviewed the theory have been critical.

In 1987 a symposium was held in Valkenburg, the Netherlands, to debate the pros and cons of AAH.

It has never been seriously scrutinized and discussed within the field of paleoanthropology and most paleoanthropologists reject the AAH.

Review of the individual claims used as evidence for the AAH generally does not support the hypothesis overall, and most of these traits have an explanation within conventional theories of human evolution.

Proponents of AAH argue that bipedalism offers numerous advantages in water, including permitting deeper wading, improved balance and reduced strain on the back, hips and knees as well as improved blood circulation.