There is nothing unusual about primates exploiting aquatic resources for food. Wading bipedally in shallow water and even diving underwater for aquatic plants or shellfish in freshwater and in marine environments has been observed in many monkeys and apes and, of course, is common in primitive human populations. So its certainly not a question as to whether such bipedal aquatic feeding behavior in humans and other primates is possible. The question is, is there any evidence that a primate species actually became– specialized– in such aquatic feeding behavior for an extensive period of evolutionary time and whether its possible humans could be descended from such primates. The aquatic ape hypothesis was first conceived by Oxford marine biologist, Sir Alister Hardy, back in the 1920s. But he didn’t reveal his hypothesis to the public until 1960 during a lecture and then in an article in the journal, New Scientist. Elaine Morgan first encountered the hypothesis after she read a synopsis of it in the Desmond Morris book, the Naked Ape. Then she wrote about it in her own book, the Descent of Woman in the early 1970s. Basically, Hardy’s argument was that humans became bipeds and developed a thick subcutaneous fat because they needed to wade into shallow water in order to get access to shellfish. I should note that aquatic wading is also one of the leading hypotheses for the origin of bipedalism in archosaurs (dinosaurs, birds, and crocodilians) I think its pretty obvious that Oreopithecus evolved its bipedalism as a wading adaptation for exploiting aquatic plants during its 2 million years of isolation on the ancient Mediterranean island of Tuscany-Sardinia. The lobulated medulla of the human kidney strongly suggest that humans were once specialized in consuming foods with an extremely high salt content. Since the African continent tends to be deficient in food resources with high levels of salt, human ancestors obviously evolved such kidneys along a marine coastline– probably an island, IMO. Marcel F. Williams
Yes, I understand all that. But it doesn't change the fact that there is no known hominid that has become specialized for aquatic feeding behaviour for an extensive period of evolutionary time. So any adaptive story Hardy or Morgan have proposed is just that, an adaptive story. It has no testable validity. All evidence indicates that we evolved in woodlands and savannas. So that is where theory should focus its attention.
Not true. Oreopithecus was a bipedal hominoid with a precision grip who was adapted to an aquatic setting for at least 2 million years on the isolated island of Tuscany-Sardinia in the Mediterranean. Harrison & Rook, Function, Phylogeny, and Fossils: Miocence Hominoid Evolution and Adaptations. 1997 “The remains of Oreopithecus bambolii are extremely abundant in VI, and this species represents one of the commonest mammals at the site…..Evidence for a primarily aquatic setting and a humid forested environment is provided by the extensive lignite accumulations, the common occurrence of skeletal remains in anatomical connection, the abundance of fossil crocodiles, chelonians, and freshwater mollusks, and the occurrence of otters…..The area was evidently poorly drained, and the forested areas were interspersed with numerous freshwater pools and shallow lakes. pg 335 “Interestingly, there is also a corresponding decline in the abundance of Oreopithecus in V2, which might simply imply a relatively narrow ecological preference by this taxon for swampy, forested habitats.” pg. 336 “Another possibility is that Oreopithecus was exploiting aquatic or wetland plants, such as water lilies, reeds, sedges, cattail, pond weeds, horsetails, and stoneworts, all of which are abundantly represented in the pollen spectrum from Baccinello.” pg. 341,
Let me rephrase myself, no known hominid has become specialized for aquatic feeding behaviour for an extensive period of evolutionary time that has relevance for the Aquatic Ape Hypothesis as it applies to modern humans. As far as we know, all of our ancestors over the past 6-8 million years lived in woodlands, savannas, and maybe rainforests.
You mean hominin. And Hurzeler and others have suggested that Oreopithecus was a hominin. Cranio-dentally, Oreopithecus is extremely similar to Sahelanthropus. And it had a foot that was similar to that of Ardipithecus. The last semiaquatic phase ended approximately 2.6 million years ago, IMO. They are the result of island isolation. I should also note that humans have kidneys like marine mammals. Humans are the only Catarrhine primate that has kidneys with medullary pyramids, a feature that is nearly universal in the kidneys of marine mammals. Marcel F. Williams