Out of Africa or Out of Eden?

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

Did man evolve on the African savannah
or
on an island paradise off the east coast of Africa

It is a common story among ancient peoples that man once used to live in an earthly paradise. In the Old Testament this paradise is known as Eden and, as with many myths, they may hold an element of truth. Darwin himself has shown that it is often within such safe and isolated environments that unusual evolution, such as that of mankind, takes place.

Where might such a paradise have existed? The most common site is Mesopotamia, where the Tigris and the Euphrates are said to mark the boundaries of Eden, but even though it is now generally accepted that this area was the cradle of modern civilisation it does not fit in with the trail of human remains and artefacts that have been found in East Africa, not just thousands of years ago, but millions of years ago. However, south of the Seychelles there is a submerged plateau which seems to fit the circumstantial evidence.

The 'Out of Eden ' hypothesis maintains that a group of primates became isolated on a newly formed archipelago called the Mascarene Plateau, during the separation of India, 65 million years ago. These primates adapted themselves to their marine environment by consciously transforming their simple reed nests into seaworthy craft. During the interglacials, approximately every 100,000 years, sea levels rose, flooded their islands, and swept some of them out into the Indian Ocean. The survivors moved along the coasts of Africa, Eurasia, India, Indonesia, China and finally into Australia and the Americas. Since the vast majority of artefact and fossil evidence can only be found on the land, any idea that 'primitive' people could use boats has been dismissed out of hand by land based archaeologists. Artefact and fossil evidence, especially sea craft, do not survive the destructive forces of the sea and the small band of marine archaeologists not only have to be trained divers but have to overcome very real dangers in their search for material, often in underwater caves.

The 'Out of Africa' hypothesis, the current paradigm of human evolution, postulates that climate changes caused the African rain forest to dry up, creating a savannah that forced our ancestors to come down from the trees. In this way they learnt to walk upright and they gradually evolved into hominids. Between 1,800,000 and 10,000 years ago, several waves of these hominids walked out of Africa into Eurasia, India, Indonesia, China and finally into Australia and the Americas. They migrated by foot and adapted to marine life well after their exodus from Africa, by which time they were indistinguishable from us - Homo sapiens sapiens.

Evidence for the 'Out of Africa' hypothesis began in 1891 when Eugene Dubois, inspired by Darwin's belief that man evolved in the tropics, found the tooth, skull and thighbone of a Homo erectus on the Solo River near the village of Trinil in Java. He named his find Pithecanthropus erectus. Later in 1929, Davidson Black discovered two similar skulls near Peking with three more being found in 1936. Many more have been found since then and it is now generally accepted that Dubois' fossil was indeed an early ancestor of Man called Homo erectus. As similar fossils were found in Africa, Asia and Europe, it became apparent that there had been a migration of these hominids from Africa.

The 'Multi-Regional' hypothesis was the first hypothesis that took account of these fossils. It postulated that one early migration of Homo erectus from Africa was followed by long periods of parallel, regional development that eventually produced the various races of Homo sapiens. Following the study of mitochondria (energy-generating structures that reside just outside the cell's nucleus), it was discovered that its DNA (or mtDNA), probably mutates at a regular rate. This fact has enabled mtDNA to be used as a "molecular clock" to trace human ancestry. This research backed up the idea that there were several waves of migration out of Africa replacing the indigenous inhabitants. This data reinforced the arguments of those who supported the 'Out of Africa' hypothesis.

The chart below shows how Hominids may have spread round the world according to the 'Out of Africa' hypothesis however, there are several serious questions that it does not address . . .


The chart below shows something of the complexity of sequencing primate fossil that have been found and dated, some of which, in Asia and Eurasia, are over twenty million years old . . .


Why did Homo erectus fossils appear suddenly, about 1.8 million years ago?
Homo erectus is a large brained hominid and palaeontologists have tried to find fossils that link them back to earlier forms but either the fossils found are too dissimilar or else they are contemporary with erectus fossils.
The 'Out of Africa' hypothesis does not try to explain this problem.

The 'Out of Eden' hypothesis shows that Home erectus fossils appeared suddenly because the migration coincided precisely with the first large scale interglacial, over 1.8 million years ago.

Why did Homo erectus migrate out of Africa in the first place?

The 'Out of Africa' hypothesis suggests that the search for game, over-population or just a kind of 'wanderlust' might be responsible for the migration of these hominids round the world. No other large mammal has spread so rapidly and so far from its original, natural habitat.

The 'Out of Eden' hypothesis maintains that there was no choice. Being washed off their low lying islands, migration was the only option for these hominids and only the fittest would have survived. Movement by sea was the reason for their speed and size of their world wide dispersion.

Why did Homo erectus migrate out of Africa in several waves?

The 'Out of Africa' hypothesis has no convincing explanation for this, nor why it should have happened several times over such a vast time scale.

The 'Out of Eden' hypothesis maintains that periodic interglacial flooding has happened several times over the past two million years. The more severe of these floods caused the hominids' periodic migrations.

How did Homo erectus and Homo sapiens cross onto islands?
Early hominids entered Australia about 60,000 years ago and onto the island of Flores at least 800,000 years ago.

The 'Out of Africa' hypothesis has no explanation for this since it maintains that Homo erectus is an entirely land based hominid.

The 'Out of Eden' hypothesis is based on the early marine expertise of the migrants enabled them to cross into Australia, Flores and all other parts of Asia and Eurasia where tribal groups over 50 would have been able to populate new territories.

Why is mankind split up into distinct racial types?

The 'Out of Africa' hypothesis suggests that the original inhabitants were entirely replaced by the newcomers. So why are there so many regional variations?

The 'Out of Eden' hypothesis suggests that the new maritime Islanders would have been vulnerable to their cousins' expertise on the land and their possession of the best habitats. Their cousins would have had time to develop their minor racial characteristics over the hundreds of thousands of years between migrations caused by natural selection and gene drift. Co-existence leading to interbreeding would have been normal.

How did big brains evolve in the hostile environment of Africa?
Erectus' heads were so large that offspring could only be born with immature brains to allow them to be pushed through the narrow bi-pedal pelvises of their mothers. Their helplessness during the first years of their lives was something that could only have developed in a benign environment and as Ernst Mayr has pointed out, major changes such as this require complete isolation.

The 'Out of Africa' hypothesis has no comment on this. It simply follows the fossil trail.

The 'Out of Eden' hypothesis maintains that the Mascarene Islands provided just such an isolated and benign environment that, over millions of years, gave the hominids, living there, ample time to develop speech, manual dexterity, hairlessness and so on.

Why is there no paleantological or archeological evidence on the Seychelles?
Surely there would be some evidence of very early habitation on the Seychelles, one of remaining islands of the Mascarene Plateau

We obviously do not know how these early Islanders lived for millions of years, but they would probably have inhabited the littoral zone, feeding off shellfish while using their reed boats for fishing. It is also likely that they buried their dead in the sea and the granite on the Seychelles is too hard and amorphous for lithic tools. Having said this, if someone wanted to find evidence there may be someting they built that has survived.

To answer all these questions it is necessary to go back 200 million years in order to explain the origins of these new hominids and their unusual habitat . . .

 


200 Million Years Ago

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

Continental Drift was first proposed in 1912 by a German meteorologist, Alfred Wegener. Using geological, zoological and palaeontological data, he showed that, around 200 million years ago, the super-continent Pangaea began to split apart into two large continental landmasses - Laurasia in the northern hemisphere and Gondwanaland in the southern hemisphere. These two super-continents continued to break apart into the various smaller continents that exist today. Twenty years after Wegener's death, his theory was finally accepted in the 1950's after an American Naval Officer, Harry Hess, chanced on the mechanism for continental drift while carrying out sonar operations during the second world war. He found that volcanic magma, pouring out from the interior of the Earth, was causing mid-ocean ridges that were slowly pushing the continents apart over the top of the Earth's hot mantle. Further study led to the new theory of Plate-tectonics that not only explains the movements of continents but also the origin of mountain ranges and such things as why British eels spawn as far away as the Sargasso Sea.



The massive Deccan Traps were caused by an eruption in the ocean floor 65 million years ago, pushing the Indian tectonic plate northwards towards Asia. Its impact created the Himalayas. The northern half of what is now the Mascarene Plateau was originally part of India when it was situated off the east coast of Africa and is shown in blue on the diagram above.

The Mascarene Plateau was left as an isolated archipelago in the Indian Ocean extending from the Seychelles to Mauritius. Its complete history is still not fully understood but it seems that the northern part was part of India while the southern parts were created later through volcanic activity. The limestone banks found on the plateau indicate that it once contained coral reefs, probably a huge archipelago stretching over the plateau.

The type of hominid that was cut off from India and left isolated on the Mascarene Plateau, when it separated from India, is unknown. All we can know for certain is that while the plateau was separating from India, 65 million years ago, there was a mass extinction and recent research shows that such extinctions are followed by explosive phyletic evolution. There is increasing evidence that India contained several advanced primates and that after colliding with Asia, these primates spread east into Southeast Asia and west into Eurasia. From Eurasia they entered Africa. Some may have survived on the land but their development was to be quite different from those that were isolated on the Mascarene Plateau.

Over the next sixty million years the isolated hominids on the Mascarene Islands had time to develop some unusual characteristics. Like their australopithecine cousins, they were already bi-pedal, but being forced to live in an aquatic environment, they learnt to swim and dive for shellfish. The requirement for diving may have modified their larynxes through natural selection which enabled the hominids to breathe so that their vocal sounds could be modified. The idea that it was an aquatic environment that gave humans their characteristic differences from other apes was first postulated by Sir Alistair Hardy and later developed by Elaine Morgan and is known as the Aquatic Ape Hypothesis. Like most arboreal primates they had inherited instinctive traits of nest-building and manual dexterity and, over millions of years, they developed these nest building instincts into the conscious creation of simple reed boats.

The construction of boats was a new factor in the survival of each group and it required the development of language to communicate concepts of design between individuals and successive generations. The development of these new skills enabled the Islanders to develop a culture that became more sophisticated than any other that has evolved in the animal kingdom.

Two million years ago, the pleasant and apparently eternal life of these hominids was about to come to an abrupt end as they entered our present Ice Age and sea levels began to fall . . .


Hypothetical view of Mascarene Islands two million years ago,
showing reeds and reed boats

 

 


2 Million Years Ago

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

At the end of Tertiary period, the earth entered the present ice age and temperatures began to fluctuate between 4C and 10C every 40,000 to 100,000 years. Using oxygen isotope data taken from the ice caps it has been possible to ascertain the Earth's climate over the past 2 million years and from this data to interpolate the resulting rise or fall in sea levels. Sea levels fell by over 100 metres, as water from the oceans became locked up in both the Arctic and the Antarctic ice caps as well as in the northern glaciers. These colder periods called glacials are a feature of our present ice age. The oxygen isotope data has enabled the creation of the chart below . . .


During the Post-Astian Fall, the Islanders would have adapted to the lower sea levels by moving down the shoreline, as sea levels fell during the first glacial. Then the first major interglacial began. Water was rapidly released from the icecaps and glaciers causing the Calabrian Rise. Sea levels rose a massive 130 metres. The settled shoreline habitat of the Islanders would have been inundated and as the ocean around the Islands rose, some of the Islanders would have been washed off the lower lying Islands. The cleverest and fittest of these hominids would have been able to reach the coast of Africa, using their reed boats. The first exodus of early man from the Islands had begun.

The migratory paths of the Islanders between 1,800,000 and 500,000 years ago follow the fossils and artefacts that have been found so far. The safest route for the drifting hominids would have been northwards along the African coast until they reached the, then flooded, Djibouti and Afar regions of Ethiopia. These flood plains would have been similar to their Island habitat and may have become the first homeland of the Islanders outside their Eden. The search for new habitats led to a gradual migration along the shores and currents of the Indian Ocean, beginning with Persian Gulf, India and Indonesia. This was followed by a migration round the Mediterranean up to the shores of the Black Sea and into the vast marshlands north of the Caspian Sea.


Natural selection
enabled the survivors of the exodus to adapt to their new terrestrial conditions in the wider world, although they kept at least part of their maritime heritage. Great efforts have been made to find the 'Out of Africa' fossil trail between Africa and India without success. As can be seen from the map above, the trail seems to go dead and even the skull found at Dmansi, in Georgia, may not to be a Homo erectus specimen.

 


500 Thousand Years Ago

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

The remaining hominids on the Island built themselves a new life in their disrupted Eden while their cousins battled for survival in the wider world. By this time their skulls were losing their inherited robustness. Strong jaws anchored to large brow ridges were no longer required for a diet of soft fish and shellfish and so their jaws and brow ridges had became smaller. It is also possible that overcrowding on the islands caused neoteny in which more infantile characteristics were selected to increase survival. With each interglacial, the ocean around the Islands rose and during the larger inundations, some of the Islanders were again washed off their low lying islands on their reed boats.


Over the next 500 thousand years
, waves of migrants travelled around the continents settling along rivers and lakes that were as similar as possible to their old Island habitat. The mingling of their genes with their existing cousins would have had the effect of widening the gene pool and allowing for wider natural selection to take place. There is no doubt that, providing relationships were kept relatively peaceful, that both the newcomers and the existing inhabitants would have had much to learn from each other.


In northern Eurasia
, one group of migrants from the Islands were trapped, 150,000 years ago, by simultaneous arctic and alpine glaciations. Over thousand of years they adapted to life hunting game on the frozen sunless tundra. Through natural selection they developed a frame similar to the present day Inuit with broad hips and more robust bones. Brow ridges re-developed in order to connect stronger muscles for their jaws to process and chew the meat they hunted. Their noses became larger in order to warm the air coming into the skull close to a brain that, through harsh natural selection had by then reached over 1500cc, larger than most of us living today. Anthropologists have named this race Homo sapiens neanderthalis.

 


120 Thousand Years Ago

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

The final inundation came about 120,000 years ago. This time the Islanders left their home for good. From now on, only the harsh law of natural selection would give a reproductive advantage to those individuals whose intelligent foresight and craft abilities aided the survival of the group.


The final migration
, made by the Islanders round the world, followed the same routes as their cousins followed before them. It is possible that by now the Islanders had larger and more advanced sailing craft so that, this time, they could reach as far as Australia, the Americas and finally the isolated islands of Polynesia. All over the world, from the huge seagoing junks and Polynesian canoes to the reed boats of Lake Titicaca, there are still echoes of our seafaring past.


Major climatic changes
took place during this final period of man's history. During the final warm interstadial, the Islanders travelled north on rivers such as the Amur. The final cold stadial, Wurm III, was a particularly severe and when the men and their boats were frozen up, they adapted their lives to hunting mammoth and other large animals, testing the various races of Homo sapiens on the Russian Steppes and Siberia to the limit. It was in these harsh conditions that natural selection adapted these humans to become strong, ruthless and intelligent. When this final glacial was over, the tribes that had survived these severe climatic changes came down from the north to force on the more effete Sea People of the south, the beginnings of what we now call 'civilisation'.

 


10 Thousand Years Ago

Out of Eden or Africa? . 200 Million Years Ago . 2 Million Years Ago
500,000 Years Ago . 120,000 Years Ago . 10,000 Years Ago

The final phase of man's development took place during our present warm interglacial when civilisation as we know it began.


During the Late Paleolithic, the domestication of animals and slaves was made possible by the development of agriculture. For the first time, large numbers of slaves and animals could be fed, allowing the elite time to carry out building projects and to pursue arts and crafts using the more talented of the slaves. Writing and numbers were developed in order to organise the increasing maritime trade.


The Bronze Age began
when the mariners round the Aegean Sea discovered how to smelt bronze using copper mixed with small amounts of tin or arsenic. Copper smelting requires a great deal of fuel and by the end of the Bronze Age, the heavily forested islands of Cyprus and Crete had been cut down, contributing to its decline.

Horses were first tamed in the Steppes of Russia and this made it possible for men to travel by horse as easily as by boat. Some of the tribes inhabiting the northern rivers of Siberia exchanged their riverine life style for a nomadic one on horseback and then came down in several waves from the north to conquer the maritime peoples of the northern Mediterranean. The Great Silk Road, the route that linked China with the Mediterranean, was first made possible with horses and mules.

The Iron Age began with the Hittites, living by the iron rich sands of the Black Sea. The Greeks, having defeated the Hittites, started using slaves to take over their iron furnaces on the Black Sea coast. Early steels were discovered by adding small amounts of carbon to iron as it was hammered over a charcoal fire. Mining developed and slave driven pumps were used to keep the mines from flooding. Unlike the smelting of bronze, this new technology required large numbers of land based slaves and, within a few generations, the maritime trading civilisations of Mycenae, Minoa, Carthage and Phoenicia were defeated first by Greece and then by Rome. Their technology and culture were absorbed into the Classical tradition and finally, as the Roman empire itself fell, in 476 AD, a small band of Benedictine monks were left to carry its cultural heritage into northern Europe, where our present Industrial Age was to have its origins.


All civilisations follow myths
, or as we say today, paradigms, and if we look at history, we can only assume that we are also embedded within our own mythologies. One of the most influential of these is Darwin's Theory - still unquestioned by the majority of scientists - and it is from this that has arisen the popular belief that 'survival of the fittest' is the creative force behind all living things. Two major philosophers of the nineteenth century, Karl Marx and Friedrich Nietzsche, were both strongly influenced by Darwin's Theory. The most infamous implementers of their respective philosophies, Joseph Stalin and Adolph Hitler must have caused more mass suffering than the world has ever known before, by enforcing their own versions of natural selection.

Several microbiologists, such as David Swift, accept natural selection as an evolutionary mechanism, but believe that it is only a partial solution. There is increasing evidence that the major changes to life took place very suddenly and were followed by long periods during which developments were made made by natural selection and mutations. Darwin's theory is quite acceptable for this 'micro-evolution', but it is beginning to become evident that it is too simplistic (and sometimes dangerous) to believe that it is responsible for major evolutionary developments or 'macro-evolution'.

While our solar system orbits round the center of our galaxy at over 200 kilometres per second, it still takes us about 200 million years to complete one orbit - about 22 times since the earth was born. Is it possible that at some point(s) around our orbit we enter areas of radiation that are both destructive and constructive? The circumstantial evidence is there, together with periodic increases in violent volcanic activity. As the evidence becomes clearer, anthropologists and palaeontologists may well have to re-interpret their fossil evidence.

The 'Out of Eden' hypothesis not only fits the circumstantial evidence of man's journey round the Indian Ocean, but it also shows just how adventurous and enterprising our ancestors must have been to survive their expulsions from the Mascarene Islands. It is this strange, isolated, evolutionary path that has separated us from the other animals. We were forced to develop our brains in order to navigate, using the sun and the stars by making use of some kind of early mathematics and before the invention of writing, we would have been forced to develop a prodigious memory using poetry and song. The sea is a hard and terrible task master but its power has enabled the creation of nature's greatest miracle.

 

Finally in memory of William Brouard Winsor, whose ideas are expressed above, his daughter, Diana Winsor, has written a novel concerning a teacher and one of his pupils who becomes involved in his lifetime's adventure of trying to discover man's origins. It is called Mr Brouard’s Odyssey, and was selected by the English Speaking Union for its 'Books Across the Sea Award' as one of the best books on British language and culture published in the last few years.

 

Appendix

The 'Out of Eden' hypothesis is based upon concepts which are explained in more detail and can be explored, using the links below:

Culture . Darwin . Genetic Engineering . Intelligence . Marine Technology . Racial Diversity



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