But the outstanding point about de Heinzelin's map is the very stability (apart from the Great Rift Valley, that noisy, bumptious recent entrant to the stability of East Africa) of the African drainage basins, most of which are in exactly the same areas they occupied 25Mya, although many of them have now broken through to the sea as the great rivers of Africa (Niger, Congo, Zambesi, Nile, Orange).

Of course, those rivers haven't 'broken through' at all. It's not as if there was a great river, pent-up and trying to get out. What really happened was that a tiny trickle on the sea side of the basin quietly eroded, bit by little bit, under its stream bed, and back through the barrier, until it backed, perhaps reluctantly, into the basin's regular seasonal flood, and let a little bit out, which next year, became a little bit more, and so on.... 

And, just so, the nil became the Nile.

The alternating glacial/pluvial cycles of just the last 10% of that 25 My time (2.5My) have seen the waxing and waning of these great drainage basins.

Lake Chad is now a mere smear of the great lake or inland sea it was until a mere 6000ya.

January 1973, Landsat 1 MSS bands 4 2 1

January 1987, Landsat 5 MSS bands 4 2 1

Indeed, it's disappearing before our very eyes.  I have changed the colour of the actual water surface to make the disaster more obvious, for disaster it is, both for the local micro-climate, and for the local people.

Chad is not suffering from massive over-extraction, for irrigation, of incoming river waters, like the similarly afflicted Aral Sea in Kazakhstan, so its shrinkage must largely be from natural causes. The Sahel area went through a very dry climate cycle, during the early 80s, that led to widespread famine.

Sure enough, though, by such a huge lake area, Toumäi, one of the very earliest hominid fossils, has recently been found there, and Australopithecus bahrelghazali, from somewhat later (about 3My) was also found nearby.

Remember, from Beadle, The Inland waters of tropical Africa (above): "Lake Chad, which during part of the Pleistocene was larger than any of the world's present existing lakes, has no surface outlet, but seeps into the sandy soils to the northeast...

Colonel Gaddafi of Libya is, right now, draining the underground waters of the Fezzan basin, with his 'Great Man-Made River Project'. The Fezzan basin is NE of Lake Chad. Perhaps the crafty old devil is sucking it all away.

Much the same type of ancient lake system applies to the now arid Arabian Peninsula, although, to my knowledge, no maps like de Heinzelin's have been produced for that area. Certainly, there were pluvial-period lakes or playas scattered about throughout the majority of the Pleistocene, during the development stages of Early Humans.

North-west of Riyadh, they're mining old water for irrigation. Huge circular fields, constantly watered by rotating hose lines, must be producing the world's most expensive vegetables.

Acheulian handaxes and other evidence of the presence of Homo erectus can be found, even by a casual tourist like me, scattered on the surface all over what are now searingly hot and dry salt flats.

Jordan has two well-known sites, Azraq (once Lawrence of Arabia's HQ), that still has scattered ponds, and is a major stopover for migratory water birds, and Jafr, now in the heart of the desert. Further south, the stored underground fossil waters of yet another great Pleistocene lake are now being mined to sustain the growing city of Amman. They won't get much more of it when it's done for.

Extensive East African Lakes

By examining soil layers at seven sites throughout East Africa, (Dr Martin Trauth of the University of Potsdam and his team) were able to identify three distinct periods during which extensive lakes covered the region and grew to depths of hundreds of metres.

They argue that the growth of these lakes resulted from a moist local climate. The regional wet periods, which may have persisted for up to 100,000 years, occurred as much of Africa became increasingly dry.

The periods of wet weather in East Africa might reflect fluctuations of the Earth's climate as a whole. At the time when the lakes grew - roughly 2.6, 1.8, and 1 million years ago - glaciers and the atmosphere were also going through major transformations.

Climate change marks dawn of man

Those three 'rough' dates: 2.6, 1.8, and 1 million years ago, are very significant in Early Human history

- 2.6 Mya - Emergence of Homo habilis - first human and first tools in Ethiopia

- 1.8 Mya - Emergence of Homo Erectus

- 1 Mya - Emergence of first 'archaic Homo'

Now ain't that a coincidence?

Freshwater or sea, the origin of humankind was deeply reliant on the shorelines of large bodies of water, and you can take your pick of the entire eastern coastline of Africa, no less than a dozen great primeval African drainage basins, or even the latecomers, the great lakes of the Rift Valley itself.

Algis Kuliukas, a leading scholar of the Aquatic Ape Theory, favours the saltpans of the Makgadikgadi basin as the site where bipedalism, the first hominid 'marker' began. Marc Verhaegen prefers a rather earlier time period with aquarboreal Miocene apes, while many adherents to the theory, including its main proponent, Elaine Morgan, prefer island isolation on a continental block fragment, the Danakil Alps, once, and often, cut off from the mainland by the onetime Afar Sea.

The 'Shoreline Diet' group (Broadhurst, Cunnane, Crawford, et al) have probably the strongest circumstancial evidence of all of early hominids' reliance on shoreline foods, but play it safe by plumping for Rift Valley lakes.

With his Delta Hypothesis, Richard Wrangham is now coming round to a new perspective:

- and has picked one of the proposed drainage basins that de Heinzelin proposed for pre-Rift Valley Africa, the Okavango 'delta', as as an example of the 'divergence site' of humans from apes.

Wrangham says:

If the first hominin evolved from a chimpanzee-like species, it could in theory have done so in the rainforest or in the savanna. Here I follow the conventional assumption that hominins began in the savanna. Accordingly, the old question, about how savanna apes became savanna hominins, has been replaced by a new problem: how did forest apes become savanna hominins? Specifically, how and why did the earliest hominins colonize the savanna, given that they came from a knuckle-walking, fruit-eating chimpanzee-like ape that depended on rainforest?

The proposal in this paper is that the LCA (the last common ancestor of Homo and Pan) must have relied initially on a chimpanzee-like diet in its new habitat.

The Okavango delta, I suggest, provides a suitable model for a transitional habitat between rainforest and other savanna habitats, because:

1) it is a (rare) example of a savanna region containing year-round access to foods that would be edible by chimpanzees, and providing sources of safety from predators;

2) such a habitat allows easy allopatric speciation, such as would be expected if chimpanzees were currently introduced to the Okavango delta; and

3) it is sufficiently large to allow a viable population.

The Delta Hypothesis: Hominoid Ecology and Hominin Origins - Richard W. Wrangham 2005 (PDF on internet?)

And then steps hesitantly into the Rubicon...

Water-crossings would doubtless have been ... alarming for the LCA: chimpanzees do not normally like to enter water. Under some circumstances, however, chimpanzees may spontaneously wade bipedally in water up to 1m deep (Gabon, C. M. Hladik personal communication; Congo, M. Ancrenaz personal communication). If the LCA were able to wade like chimpanzees, they would have been able to negotiate the waters of the Okavango delta at least as well as baboons. They would also have been able to reach Nymphaea stems growing more than an arm’s reach from the bank. Facultative bipedal wading would therefore have been a useful adaptation for the LCA occupying an inland delta. Wrangham 2005

But others have also dipped their toes in the Rubicon: ‘One of the strong points about the aquatic theory is in explaining the origin of bipedality. If our ancestors did go into the water, that would forced them to walk upright’. Stringer, 1997

For example Verhaegen et al. (2002) suggested that hominin ancestors “fed partly on hardshelled fruits and molluscs”, on the basis of evidence such as dental similarities to mollusc-eating sea otters (Enhydra lutra), the human capacity for voluntary breath control, and the expectation that bipedalism would be associated with wading. They considered that the ancestor of australopiths could have come from a Miocene ape ancestral to chimpanzees and gorillas, so they did not expect the LCA to be chimpanzee-like. It wasn't Marc Verhaegen who first suggested that a human's teeth were remarkably like those of a sea otter, but Alan Walker, very much a 'savannah' man. 'This species possesses small anterior teeth, and large, flat molars with thick enamel'.   As noted by Verhaegen et al. (2002) and many other authors, fossil hominins are frequently associated with wet habitats, doubtless partly a taphonomic bias*. Wrangham 2005   (*That is, you find dead bones in wet places, because mud's a good medium for preservation. But then, you find stone tools in wet places, too. Mud does nothing very much for them).   Kathy Schick points out that "the majority of known Acheulean sites from anywhere in the world are found in fluvial contexts"  Kathy Schick An Examination of Kalambo Falls Acheulean Site B5 from a Geoarchaeological Perspective. In Kalambo Falls Prehistoric Site Vol III The Earlier Cultures: Middle and Earlier Stone Age. edited by J. Desmond Clark. Cambridge: Cambridge University Press 2001. Pp. 463-480.   This scenario also raises the possibility that the composition of the Okavango as a network of islands could favor the evolution of bipedalism. For those who envisage bipedalism as facilitated by the need to traverse or exploit aquatic environments, an inland delta that generates low islands termitogenically¹ or hydrodynamically² offers rich scenarios. The Delta Hypothesis: Hominoid Ecology and Hominin Origins - Richard W. Wrangham 2005 (PDF on internet?)

(¹ ² - ie, made by termites or by running water)

Harrummph!!

Sounds a bit like old Dick is going down that barmy 'Wet Ape Theory' path!

Although he does it circumspectly, by ritually invoking the Holy Assumption that Hominins Began in the Savanna. He's not quite ready to be an iconoclast yet.

That sort of thing is only allowed for the really Grand Old Men of palaeoanthropology, like Philip Tobias.

Philip Tobias's Repudiation of the Savannah Hypothesis

"My disavowal of SH was based in the first place on evidence which had been coming forth from excavations in South and East Africa. From Sterkfontein, suggestions of greater woodland cover at the time when Australopithecus was deposited in Member 4, had emerged from studies on fossil pollen, but these were not compelling. Then Wits team member Marian Bamford identified fossil vines or lianas of Dichapetalum in the same Member 4: such vines hang from forest trees and would not be expected in open savannah. The team at Makapansgat found floral and faunal evidence that the layers containing Australopithecus reflected forest or forest margin conditions. From Hadar, in Ethiopia, where "Lucy" was found, and from Aramis in Ethiopia, where Tim White's team found Ardipithecus ramidus, possibly the oldest hominid ever discovered, well-wooded and even forested conditions were inferred from the fauna accompanying the hominid fossils.

All the fossil evidence adds up to the small-brained, bipedal hominids of four to 2.5 million years ago having lived in a woodland or forest niche, not savannah. The evidence for the presence of big forest trees supports the idea we had gleaned from the bones of "Little Foot" that tree-climbing had been a part of the lifeways of these early African hominids. At least, one could conclude, there had been trees big enough to bear the weight of the Australopithecines (for which stunted acacias of the savannah would have been unsuitable).

To a large London audience in 1995 I said: "All the former savannah supporters (including myself) must now swallow our earlier words in the light of the new results from the early hominid deposits... Of course, if savannah is eliminated as a primary cause, or selective advantage of bipedalism, then we are back to square one."

Humans are not savannah-adapted animals

In rejecting the SH, I was moved primarily by the evidence unearthed in South Africa and East Africa. Meanwhile, Elaine Morgan had been piecing together a number of other arguments against the SH, based on some anatomical, biochemical and physiological data of modern humans, much of which was collected by Belgium's Dr Marc Verhaegen, which contrast sharply with the traits in present-day animals that are truly adapted to savannah life.

As examples, modern humans lack sun-reflecting fur and are virtually hairless. The cooling system in our skin is quite unfit for hot, dry, exposed environments: we have numerous sweat glands and we waste water and sodium - not very suitable for life on the savannah. Our ability to concentrate our urine is poor and too low and if ever our earliest ancestors were savannah dwellers, we must have been the worst, the most profligate urinators there.

Adapted savannah-dwellers need to drink more water at a time, but most humans are not able to drink much at a time. The quantity of our subcutaneous fat, which would insulate us against heat loss, is never found in truly savannah-adapted animals.

In our bodily functions, chemistry and microscopical anatomy, we should be hopeless as savannah-dwellers. So Marc Verhaegen and Elaine Morgan, in her remarkable book, The Scars of Evolution, came to the same conclusion that we had reached from quite different lines of evidence: the old Savannah Hypothesis was not tenable. All former savannah supporters must recant ­ and this I did in London. It was an exciting moment - living through a change of paradigm.

Max Planck, the German physicist and Nobel laureate, once wrote these words on the replacement of an outworn paradigm: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows that is familiar with it."

That must be one of the masterpieces of cynicism on the scientific process. Paradigm changes, I like to think, flow overwhelmingly from new evidence and, where the evidence is sound and even irresistible, they should be embraced just as lief by the old as by the young. It was three weeks after my 70th birthday and I went on to declare, "A change of paradigm shakes us up; it rejuvenates us; and, this above all, it prevents mental fossilisation - and that is good for all of us."

Philip Tobias

Major Climate Change 2.5 to 2 million years ago

From 2.5 to 2 million years ago, coincident with the onset of major northern hemisphere glaciation (mostly growth of polar ice caps), the climate became cooler and drier (Shackelton et al. 1984; Versteegh et al. 1996).

The environment was more similar to that of the present (Bonnefille, 1983), but was not yet dominated by savanna grassland (Cerling, 1992).

And the earliest known fish dinner was found there. It is not known whether Early Humans used crude choppers or bifacial handaxes to process the chips. Newspaper wrapping was unknown at the time.

See: Where is the Evidence?

Wrangham 2005

Wrangham avoids the problem of progressing to other forms of aquatic food, very simply:

Verhaegen et al. (2002) suggested that hominin ancestors “fed partly on hardshelled fruits and molluscs”, on the basis of evidence such as dental similarities to mollusc-eating sea otters (Enhydra lutra) ... such proposals are incomplete unless they can explain how the posited foods can be found in sufficient abundance all year.

Molluscs and fish are available throughout the year, and fish are especially 'fat' at the end of the dry season, as they spawn and are caught more easily during the very first rains, when other foods may not be available.

See: Olduvai Fish

Then goes on to say:

In my own experience, savanna lakes sustain few or no trees that produce year round fruits edible by primates (e.g., Rift Valley lakes in Kenya and Tanzania). This raises the possibility that for fruit-eating hominins lake margins would normally have been impoverished habitats unless they included deltaic areas receiving year-round water.

All the more reason to try fish and molluscs.

Then he gets on his favourite hobby-horse, USOs:

It would then presumably rapidly evolve in the direction of a hominin diet by incorporating underground storage organs. Appropriate changes in teeth and guts would follow. This scenario conforms to the fact that the molars of Sahelanthropus are rounder and have thicker enamel than those of chimpanzees, suggesting a greater use of underground storage organs (Brunet et al. 2002). (Or molluscs)

Be thankful for small mercies - at least he's not saying they'd off across the savannah to bag a brace of bucks with their bifacials.

The Delta Hypothesis: Hominoid Ecology and Hominin Origins - Richard W. Wrangham 2005 (PDF on internet?)