Naish's post shows how much misunderstanding there still is about AAT, or better about the Littoral Theory.
Our ancestors' littoral past has nothing to do with Ardipith, Sahelanthropus or australopiths, of course: it was about Pleistocene Homo spreading along coasts & rivers to different continents & even islands, eg, Flores c 900 ka >18 km oversea! There's nothing mysterious about it, and we have all the fossils: all archaic Homo fossils are found in littoral sediments from Mojokerto to the Cape to Pakefield & Boxgrove. It's obvious they did not get there running over plains! They simply followed the coasts & the rivers inland, where these dextrous omnivores fed on different sorts of waterside foods: stranded whales, drowned ungulates, cattails & cane, birds' eggs, shell- & crayfish etc. It was there that we got our huge brains (DHA), fur loss & fat layers, our head-spine-legs in 1 line, our external nose etc.
Naish's post has only 1 +-sensible sentence: "... at least some fossil humans & human relatives foraged on shorelines or in mangroves, waded in shallows, or ate aquatic foods like crabs, stranded fish & shellfish." This is much too weak, of course: archaic Homo shows pachyosteosclerosis (google), a feature that is typically & exclusively seen in slow & shallow littoral divers: among mammals, eg, sea-cows, walruses & several fossils (AFAIK: Ichthyolestes, Pakicetus, Basilosaurus, Zygorhiza, Ambulocetus, Indohyus, Odobenocetops, Valenictus, Kolponomos & some Thalassocnus spp).
If one wants to write something on the littoral theory, one has first to in form a bit.
In 1995, professor Phillip Tobias, in his Daryll Forde Memorial Lecture at University College, London, stated of the Savannah Hypothesis: "We were all profoundly and unutterably wrong! All the former savannah supporters including myself must now swallow our earlier words ..." In spite of this, the savannah ideas are apparently still taken for granted in most popular books & articles on human evolution. We think the death of professor Tobias must be an opportunity for paleo-anthropologists to finally get rid of the dry savannah fantasies.
It was Tobias' predecessor at the Witwatersrand University, Raymond Dart, who helped the savannah ideas to become generally accepted. In the 1920s, geologists thought the climate in South Africa had not changed since the Pliocene, so Dart concluded that the Taung child (a human ancestor, he believed) had lived in dry grasslands. We now know that Taung was possibly no human ancestor, and moreover lived in "a more forested habitat, with denser cover along waterways" (Berger & Clarke 1995). If some hominids lived in savannahs, it must have been along the forested rivers, swamps & lakes there, where their fossils have been found.
H.erectus, with its extremely heavy skeleton could not have practiced endurance running (a still popular fantasy, even among paleo-anthropologists).
One of the last publications of Professor Tobias was "Revisiting Water and Hominin Evolution", the first chapter of an ebook devoted to our ancestors' waterside evolution:
Mario Vaneechoutte, Algis Kuliukas & Marc Verhaegen eds 2011 Bentham Science Publications,
"Was Man More Aquatic in the Past? Fifty Years after Alister Hardy: Waterside Hypotheses of Human Evolution".
Although it is clear that Pleistocene Homo was more aquatic than Homo sapiens is today, how aquatic they were is still debatable. Any scientific discussion of human evolution should take into account this ebook, which contains contributions of all major proponents of waterside hypotheses.
Please also google "econiche Homo" & for ape evolution "aquarboreal", and please contact me for our recent paper in HOMO - Journal of Comparative Human Biology 62:237–247, 2011 "Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods"
Marc Verhaegen & Stephen Munro 2011:
"Fossil skeletons of Homo erectus and related specimens typically had heavy cranial and postcranial bones, and it has been hypothesised that these represent adaptations, or are responses, to various physical activities such as endurance running, heavy exertion, and/or aggressive behavior. According to the comparative biological data, however, skeletons that show a combination of disproportionally large diameters, extremely compact bone cortex, and very narrow medullary canals are associated with aquatic or semi-aquatic tetrapods that wade, and/or dive for sessile foods such as hard-shelled invertebrates in shallow waters. These so-called pachyosteosclerotic bones are less supple and more brittle than non-pachyosteosclerotic bones, and marine biologists agree that they function as hydrostatic ballast for buoyancy control. This paper discusses the possibility that heavy skeletons in archaic Homo might be associated with part-time collection of sessile foods in shallow waters."