This is a theory stating that humans evolved via an aquatic or semi-aquatic stage and that this fact accounts for many features seen in human anatomy such as hairlessness, standing erect, bipedal nature etc. At the least it proposes that human ancestors spent quite some time adapting to semi-aquatic or marshy habitat if not in a completely aquatic scenario using the principle of convergent evolution. It asserts that life in an aquatic environment explains these features thus it is important to have an aquatic stage in the transition from ape to hominid to human beings as we know us know today. Origin:
The theory was first proposed by Max Westenhöfer- a German pathologist around 1942 and then by independently Sir Alister Hardy (knighted in 1957) a noted British Marine Biologist in the year 1960.This idea emerged mainly from the fact that we observe many human traits that draw a strong parallel to aquatic mammals and sets them apart from other primates. Since this hypothesis was somewhat controversial and outside the expertise of Hardy, he was quite hesitant in voicing it .He defined it as the following- according to his thesis a branch of this primitive ape-stock must have been forced out of arboreal life due competition due to other group of terrestrial animals hence having to feed from sea-shore and shallow water of coast feeding on stuff like sea urchins, shell-fish etc. He also proposed it to happen in the warmer parts of the world where man could stand in water for relatively long. Later it was supported by a writer named Morgan. Finally other versions suggested littoral i.e. near the shore feeding and wading rather than strong aquatic adaptations. Evaluation of the hypothesis:
Nicknamed as AAH or AAT the theory suggests that many features that set humans apart from closely related primates are due to adapting to a period of aquatic or semi-aquatic wading, littoral feeding lifestyle however followed by returning to land before becoming fully adapted to such a life. Many traits have been proposed to indicate this few of them are mentioned and analysed below- • Bipedalism-
-Proponents of AAH say that it offers many it offers many benefits in water such as permitting wading, improved balance, reduced strain on back, hips, knees and a better blood circulation.
- Proponents of the AAH suggest that bipedalism is disadvantageous when comparing humans to medium-sized, terrestrial quadrupeds hence it rules out terrestrial ancestor to some extent.
- elongated lower limbs of humans for improving swimming speeds Counterview
-Bipedalism is quite beneficial on land benefits itself its pros including lower energy expenditure and the ability to run long distances.
- Fossil record shows that the evolution of humans from ape ancestors didn't include a period of quadrupedal locomotion. Instead, human evolution features mainly brachiation, suspension and climbing as the primary method of transportation, with a gradual increase in bipedal locomotion overtime.
- Elongation of limbs 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. Hence this brings us to square one and the only undisputed benefits of bipedalism is the fact that it frees 2 hands for using tools, taking care of children etc. •Hairlessness-
-It is claimed that the relative hairlessness of humans is due to comparable adaptations in aquatic mammals and land-dwelling mammals that may have aquatic ancestors as well as those that currently spend much of their time in wet conditions.
- incase human hairlessness is to support vigorous sweating this mechanism is very wasteful of water and unlike other medium-sized mammals in the hot savanna environment do not use this mechanism of heat loss
-the loss of fur has required the development of a significantly costly form...