When Phillip V. Tobias, one of the world's experts on human evolution, called to say he wanted to expand one of his latest theories, we said "Go ahead!"
Skull of Mr Ples, a large male Australopithecus africanus, found in Sterkfontein Member 4 by the late Alun Hughes in 1989.
Africa's apeman sites
SOUTH AFRICA'S FAMOUS fossil apeman sites - Taung near Kimberley, Sterkfontein, Swartkrans and Kromdraai near Krugersdorp, and Makapansgat near Pietersburg - are situated in what is today the dry hinterland of the sub-continent. So is the Olduvai Gorge on the Serengeti Plain of Tanzania, Koobi Fora in the north and north-east of Kenya, and Bahr-el-Ghazal in the Chad Republic in the Sahara Desert.
Yet, wherever the early members of the human family were evolving, they needed water to drink and to keep cool. Proximity to water was the most important factor in the location of an evolving group like the early hominids. They must have lived near springs, rivers, lakes and freshwater estuaries. Denied water in warm, tropical or sub-tropical climates, humans quickly become dehydrated and death may follow in days. Water is necessary for survival and an essential ingredient for evolutionary change.
Water and human dispersal
Water helped distribute humans across the planet, along seashores, lakes and river banks. This would have accounted for the prehistoric peopling of most of the Old World, from Africa to Europe and mainland Asia. Strolling or swimming along the beach would have been sufficient to carry mankind from the Horn of Africa to the Peloponnesos of Greece, from the Levant to the Korean Peninsula, from Singapore to Siberia. When much water was bound up on land as glaciers in the Ice Ages, sea levels were lower than they are today, and previously submerged land-bridges appeared, helping spread humans to new parts of the earth. At such times, it would have been possible to walk dryshod from Tripoli and Tunisia to Malta and Sicily, from South Korea to South Japan and from the Sakhalin Peninsula to Hokkaido, North Japan, from Malaysia to Sumatra, Java and Bali and from Siberia to Alaska over the 500km-wide land connection called Beringia.
At some stages and in some places, humans learned to cross the water, even without a land-bridge. Java and Bali were periodically connected to the Asian mainland, so that animals, including humans, could easily cross to them. However, the Indonesian island of Flores could be reached only by sea crossings even when the sea level was lowest. Yet stone tools and fossil bones on Flores show that humans (probably Homo erectus) and archaic elephants (Stegodon) must have crossed this 19km-wide, deep oceanic channel 900 000 to 800 000 years ago. There is no evidence that they knew how to make boats so early. Either they floated across using tree trunks and logs as rafts, or they swam.
Another deep oceanic channel - the Strait of Gibraltar - lies between Ceuta and Morocco in North Africa and Gibraltar and Spain. The strait today is about 13 km at its narrowest point but when the sea-levels of the Atlantic and Mediterranean were lower, the distance across was smaller and a few islands (presently under water) would have appeared. The greatest sea crossing then would have been only five kilometres. Stone tools and probable fossil hominid remains between 1.5 and one million years old have been found in south-eastern Spain near the village of Orce and the city of Murcia. For a long time, the question has been: how did these earliest Europeans get to the Iberian Peninsula from North Africa? There are two fairly obvious overland routes one through the Middle East across Suez and the Levant, and one from Tripoli, via Malta, Sicily, the Strait of Messina to Calabria, the toe of Italy. To get to the south of Spain from either of these two passages would have involved taking the long way round, including the crossing of the Pyrenees in a southerly direction. Several of us have been pursuing the option of the short cut the water traverse from Ceuta to Spain. If people and elephants could get across a wider channel to get to Flores just under a million years ago, I believe it is very likely that the smaller water crossing of the Strait of Gibraltar would have been within human capacity just over a million years ago. Again, floating, rafting on flotsam and possibly even swimming seem to have been early acquisitions in human cultural and behavioural evolution. Boats are technologically advanced inventions which probably came much later.
These are details. The principle remains that water must have played a crucial role in the distribution of humanity across the planet.
Semi-aquatic human ancestors?
The third way in which water is thought by some to have affected human evolution is a nearly 40-year-old proposal, the Aquatic Ape Theory (AAT), which holds that mankind evolved some of its distinctive features in an aquatic environment and that ancient human ancestors spent more time in the water than present-day descendants. As Graeme Addison explained in Out There (January 1998), Sir Alister Hardy put forward the idea that man was more aquatic in the past, following Max Westerhofer's 1923 proposal that some modern human anatomical features indicate an aquatic form of adaptation.
The idea was largely ignored by Hardy's contemporaries. There are two ways in which a new idea in science is rejected: one is by direct confrontation and attempts to refute it; the other is by turning a blind eye to it and hoping that it will simply go away.
Among those who opposed the AAT, some pointed out that there were no fossils to support it. One is tempted to ask what sort of fossils did they expect? Those fossils already discovered in South and East Africa, four to three million years old, show signs that they belonged to erect bipedal hominids. One of the things the AAT proposed was that the early hominids developed uprightness to hold the head above water while wading. Claiming that water-adapted fossils had not been found, amounts to a circular argument when the theory of water-adaptedness purported to explain the very erectness of those fossil skeletons that had been found!
When a new idea is rejected, it is frequently because it flies in the face of an accepted prevailing paradigm, in this case the Savannah Hypothesis (SH).
The Savannah Hypothesis
From 1925 to 1995 almost everyone grew up on the "received wisdom" that the Hominidae (the family of mankind) was born on the savannah, believed to have been the ideal crucible in which the strange form of locomotion known as bipedalism came into being. The idea is an old one. Robert Broom, in his 1933 book The Coming of Man: was it Accident or Design? stated: "Before Australopithecus was discovered some of us believed that the ancestor of man would be found in an anthropoid ape which had left the forest and taken to living on the plains and among the rocks; and here (in Australopithecus, the Taung child) we have just such a form."
Raymond Dart's 1925 paper, that announced the features of the little fossil child from Taung, included this passage: "For the production of man a different apprenticeship was needed to sharpen the wits and quicken the higher manifestations of intellect a more open veldt country where com-petition was keener between swiftness and stealth, and where adroitness of thinking and movement played a preponderating role in the preservation of the species... in my opinion, Southern Africa, by providing a vast open country with occasional wooded belts and a relative scarcity of water, together with a fierce and bitter mammalian competition, furnished a laboratory such as was essential to this penultimate phase of human evolution." (Emphasis mine)
From the animal remains found with the Australo-pithecus child, Broom (1933) wrote, "... we can safely infer that the rainfall was then, as now, scanty, and that there were no forests in that region, only grassy and bushy plains from which the hills and krantzes arose."
My generation grew up steeped in what more recently has been called the Savannah Hypothesis. As Elaine Morgan has chronicled in her book, The Aquatic Ape Hypothesis (1997), this view was supported, directly or indirectly, by numerous scholars, including Sherwood Washburn, Kenneth Oakley, Richard Leakey, Peter Wheeler, Alan Walker. It was a paradigm that lasted for about 70 years of this century.
In 1980, the Africanist archaeologist J. Desmond Clark put forward a modified version of SH which favoured a mixed ecology. He said "there is little doubt that proto-hominids (ancestors of hominids) were widely distributed throughout the tropical savannahs. It seems certain that it was within habitats consisting of mosaics of grassland, woodland, and forest that the hominid line first became differentiated from that of the pongids (the apes)." Clark singled out not only the great richness and diversity of plant and animal resources in the savannahs compared with the forest, and the fragmentation of the forest cover during the later Miocene-early Pliocene, which isolated some hominid populations, but also the progressive expansion of grasslands from that time onward, which made available "empty niches" into which hominids could expand. These factors, he believed, "can be expected to have led to a number of adaptations".
In 1985, Elisabeth Vrba suggested that the family of man was probably a "founder member" of the African savannah fauna! That year, I published a chapter called "The conquest of the savannah and the attaining of erect bipedalism" in which I expressed the old idea: "The living apes of Africa are to be found exclusively in the wet forest of the middle reaches of the continent. It is likely that ancestral apes, too, were forest-dwelling creatures...The spread of lighter woodland and savannah and the retreat of the margins of the primaeval forests could well have created conditions in which the tendency to uprightness and bipedalism was favoured. The ability to run across the high grass cover of the savannah, perhaps from one woodland-girt stream to another, might have held advantages for those apes which could 'walk tall'. Uprightness gave its possessors a chance to see over the tall grass and to watch out for predatory enemies like the lions and sabre-toothed big cats. Seemingly it was under just such a set of conditions that the Hominidae made their appearance upon the face of the earth."
That statement may well be the quintessence of the SH - and I believe it was my last statement in support of it. By 1995, when I gave the Daryll Forde Memorial Lecture at University College, London, I stated of the SH, "We were all profoundly and unutterably wrong!"
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 17th 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."
What the demise of the SH means for the AAT
My formal slaying of the SH removed a key objection to the AAT. Supporters of the Hardy-Morgan concept hailed this event as my espousal of the aquatic ape hypothesis. This was not strictly correct for there were other theories on the ³primary causes² of bipedalism, though, to my knowledge, there was none to explain those physiological and biochemical aspects which seemed to ally us to marine mammals. Now, at least, anthropologists should be able to examine this with a more open mind than previously when the thinking of so many was clouded by the SH.
It seems, however, that the name Aquatic Ape Theory has become a handicap. For nearly 40 years since Hardy first put the idea forward, AAT has been a bit of a joke to many scientists, conjuring up visions of a creature that spent all - or almost all - of its time in the water. Yet Hardy's original 1960 article was modestly entitled, "Was man more aquatic in the past?" In scientific writing a name can send very misleading messages and the term "Aquatic Ape" does just that. Replace it with something else, I urged Elaine Morgan. Then, I think the implications of those apparently water-adapted features like humans' loss of hair will receive less cynical attention from those who have hitherto smirked at the mere mention of "The Aquatic Ape"!
At the Dual Congress at Sun City in 1998, Marc Verhaegen and Pierre-Francois Puech of France summed the evidence that hominid evolution did not begin in warm and dry, but in warm and wet conditions. This included new thinking on what one can infer from the micro-wear on the teeth as to the food of early hominids: they found signs of marshland plants, molluscs, aquatic herbs.
Dr Michael Crawford of the Institute of Brain Chemistry and Human Nutrition, London, Dr L Broadhurst of the USA., and other collaborators presented an unexpected and fascinating study. In his book The Driving Force: Food, Evolution and the Future (1989), Crawford explores many issues around "the land-water interface". To develop the large brain characteristic of the hominids, a chemical known as DHA was necessary. The lack of DHA in savannah food may explain the "degenerative evolution" of the brains of savannah species and the reason why Homo sapiens could not have evolved on the savannahs. The marine food chain, on the other hand, has an abundant supply of DHA. Early hominids had to make use of the marine food chain to enable the evolution of brain and brain size to keep pace with body size. Their claim that the human brain depended on the marine food chain suggests independent evidence in support of the importance of water in human evolution.
In the face of all this evidence, old and new, it is time for human evolutionists to open their minds and give fair and objective thought to the role of water in the evolution of mankind. We need a new holistic emphasis on water: first for drinking, secondly as a source of food from aquatic plants and animals and, thirdly, as waterways facilitating - or impeding - the spread of humanity across the globe. Fourthly, we may no longer shy away from the questions posed by those especial features of the human skin, sweat-glands, chemistry of sweat, body temperature control and fluctuations, heat and radiation tolerance and water consumption, which in modern humans appear so different from those of savannah-adapted mammals and so reminiscent, in some cases, of aquatic mammals.
As the Savannah Hypothesis still held sway when the Valkenburg Conference on AAT took place 11 years ago, many arguments raised at that meeting are no longer tenable. Another international forum should be set up to explore the whole question in the light of the demise of the SH - but please, let it be under a different name!