The AHAH timescale is largely based upon the widely accepted multiple (usually two) Out of Africa diaspora model as promoted by Prof Chris Stringer of the Natural History Museum and is summarised in the "River Apes" poster.

Out of Africa I
According to this theory the genus Homo originated in or around Africa before 2 million years ago. There was then a diaspora of hominids from Africa to Europe and Asia, resulting in the significant fossil finds of Homo erectus, Homo neanderthalensis and other 'human-like' people. There is a great deal of consensus about this part of the model.

Out of Africa II
More controversial is a second diaspora espoused by Stringer. This suggests that the ancestors of every human alive today was still African even quite recently - around 250,000 years ago. This idea, backed up by detailed morphological studies into fossils and especially by the vast bulk of molecular and genetic data, claims that modern Homo sapiens sapiens emerged in Africa very late and then exploded out of Africa, completely replacing all previous ancient human populations that lived there before them.

It should be noted that there is still some  controversy about this part of the model and many are opposed to it on both sides of the AAH debate. 'Aqua-sceptic' paleoanthropologists include  Milton Woolpoff and AAH proponents  who are sceptical about Out of Africa II include Marcel Williams.

But, generally, it is argued here that the AHAH model and timescale sits on top of Out of Africa (I and II), which is currently a standard and quite widely accepted idea.

Out of Afar?
The Out of Africa model predicts that the genus Homo arose in Africa around 2.6 mya and then spread to eurasia before a second wave of people, Homo sapiens, emerged again from Africa, much later, as recently as 100,000ya.

Some of the best evidence for this is the genetic data which show greater variation between populations of people within Africa than outside. This is a good indicator that the species origin ated there. Some further studies using the same kind of logic have suggested that East Africa, and Ethiopia specifically, are most likely, within Africa, to be the ancestral home of the species.  The AHAH model only takes this idea a little further in speculating that the Homo sapiens speciation event occurred in the Afar triangle due to a hybridisation event between two hominin subspecies.

So it is proposed that the AHAH model is fairly consistent with broadly accepted timescales today. More detail will now be added to this model much of which, of course, will be viewed as controversial to some. One valid criticism of this model is that this is very much a "just so story" and it is not claimed to be anything else. It is merely contested that this 'just so' story fits the evidence as well as any other and it is on that basis that it should be judged. 

The Hominoid lca - Phase I
One of the many huge gaps in the fossil record that can still be aptley labelled the  'missing link' in human evolution is that for a good candidate for the putative last common ancestor of all the great apes (Hominoidae.) The AHAH is no wiser than any existing model in this regard and is based upon Marc Verhaegen (and others') so-called 'aquarboreal model which claims that the earliest hominids were semi-aquatic wading apes, rather in the mould of proboscis monkeys today. The AHAH phase 1 suggests that these apes

inhabited mangrove forest habitats along the Red/Med/Tethys Sea on the Afro-Arabian coasts. It is proposed that such wading apes lived in small pockets around the Miocene and that Oreopithecus, an earlier ape not thought to be on the hominid line was an analogous example of such a species. It is further proposed that the extensive glacial flooding/desiccation cycles associated with the Red/Med/Tethys sea in the Miocene ultimately destroyed this population of ancestral apes.

Phase II
The second phase of the model is perhaps the most speculative. It proposes that some of these 'aquarboreal' apes which had migrated in-land along the Rift valley by 7-8mya became adapted to inland semi-aquatic forest niches (riverside, lakeside, swamp, river delta etc.) It is proposed that these were the ancestors of Gorilla and Pan. Others had settled in the forests around Afar triangle. When this region flooded, around 4mya, it is proposed that a group of these apes became isolated on several small volcanic islands and the much larger Danakil island (now Danakil alps). This process of isolation removed the threat of predators allowing them to come down from trees and become more terrestrial. It also may have protected them from a baboon retro-virus which appears to have been very virulent in Africa around this time. Having greatly depleted food sources, the survivors were forced to use other sources including coastal foraging, leading to adaptive pressure for (in temporal order) wading, swimming and diving.

Phase III
Between 3.5 and 2 mya it is suggested that the African fresh-water wading apes underwent a major radiation resulting in a diaspora of bipedal (wading) australopith species across much of Africa. It is proposed that these were the ancestors of Gorilla and Pan and that knuckle-walking was a reversion to quadrupedalism from an earlier, more bipedal, mode. It is suggested that this would happen  as Africa dried and the waterside habitats of the wading apes
(Phases IV-VII)