The Ocean of Churn: How the Indian Ocean Shaped Human History

by Sanjeev Sanyal

  There is some dispute about the exact trajectory of the northward movement, but around 55 million years ago India collided with the Eurasian plate. The collision pushed up and created the Himalayas. As a result, the seabed that had existed between India and Asia was thrust into the sky. This explains why fossils of marine animals can be found high up in the mountain range.2 The Indian plate continues to push into Asia and the Himalayas are still rising by about 5 mm every year. This is why the Himalayan range is seismically very active and experiences frequent earthquakes.

  Meanwhile, Australia and Antarctica began to tear apart like a zipper between 85 and 45 million years ago. Once separated, the Australian plate shifted north and became fused with the Indian plate, thus creating the Indo-Australian plate. This is a very simplified version of the sequence of tectonic events that created the Indian Ocean, and the process is still not complete. The Red Sea is the result of a growing rift between the Arabian and African plates, while East Africa is breaking away from the rest of the continent thereby creating the East African Rift Valley—the landscape where our species evolved.

  We may even be witnessing the creation of new rifts. The western coast of Sumatra, Indonesia, runs along the boundary between the Indo-Australian plate and the Sunda plate (which covers much of South East Asia). This is why the area is prone to frequent earthquakes and tsunamis; this is what caused the deadly tsunami of 26 December 2004. Lesser known are a pair of strong undersea earthquakes that took place off the Sumatra coast in April 2012. These two quakes took place away from the main fault line and seismologists see it as a sign that the Indian and Australian plates are separating. The reason for this new rift is that the collision of the Indian plate into Asia has slowed it down whereas Australia is still moving quickly.3 The resulting pressures will now cause the Indo-Australian plate to break into its constituents—a process that will probably cause frequent earthquakes in this area and could produce deadly tsunamis in the future.

  In addition to tectonic movements, the Indian Ocean landscape is constantly being moulded by many other natural and environmental factors. The coastlines, for instance, have moved as the sea level has changed due to the periodic warming/cooling of our planet. Since the peak of the last Ice Age 18–20,000 years ago, the sea level has risen by 120 metres as the ice sheets have melted. This process flooded the coasts and, as we shall see, had a major impact on early human history. The sea level began to stabilize about 7000 years ago (i.e. 5000 BC) and remained broadly unchanged between AD 0 and AD 1800, but it has again begun to gradually rise since the nineteenth century.4

  Numerous other factors also affect the Indian Ocean landscape—the shifting of sand and silt by ocean currents and rivers and, of course, human intervention. The complex interaction between all these factors means that the landscape is alive and constantly changing. Till very recently, histories were written as if the terrain was static but a growing number of researchers have begun to incorporate the impact of an evolving landscape into their writings.

  Of Humans Big and Small

  Modern humans appeared in the East African Rift Valley about 200,000 years ago. Being an exceedingly modest lot, and despite plenty of evidence to the contrary, we would come to name ourselves Homo Sapien, that is, ‘wise man’. Note that there were several other hominids around at that time and it would not have been obvious at this stage that Homo sapiens would one day be the sole surviving human species. The Neanderthals were well established in Europe and the Middle East. The closely related Denisovans roamed across many parts of Asia. We have only discovered the existence of the Denisovans by chance in 2010 due to the genetic sequencing of an ancient finger bone.

  There were also isolated remnants of earlier human groups. On the small island of Flores, Indonesia, one such group went through a process of dwarfing. It is unclear how archaic humans reached this island but it is likely that this happened at a time when sea levels were low and the island was easily accessible from the mainland. When sea levels rose, the group became trapped on an island with limited resources. In response to scarcity, the survivors reduced in size and evolved into a species named Homo floresiensis that reached a maximum height of one metre and a weight of 25 kgs. Nonetheless, they continued to produce stone tools and seemed to have hunted the island’s dwarf elephants. There is evidence to suggest that this dwarf species may have survived till as recently as 12,000 years ago.5

  At some stage, early Homo sapiens began to expand out of their original habitat in the Rift Valley. Thus, the first human eyes to look upon the open sea would have seen the waves of the Indian Ocean crashing into the East African shore. We know that at least one group migrated north, and archaeological remains found at the Skhul and Qafzeh caves in Israel suggest that Homo sapiens reached the Levant around 120,000 years ago. However, this initial foray out of Africa appears to have been unsuccessful and this group either died out or withdrew back into the African continent. Perhaps the climate turned colder and the Neanderthals, better adapted to cold, reoccupied the area.

  So who were these early Homo sapiens? Genetic surveys suggest that the Khoi-San people of south-western Africa are the oldest surviving human population as they have the greatest genetic variation.6 Note that Khoi-San is a composite term derived from the hunter–gatherer San people, also known as Kalahari ‘bushmen’, and the closely related Khoi people who engage in herding. Right at the onset, let me clarify that the Khoi-San are not a relic population of ‘living fossils’. They are modern Homo sapiens who happen to carry the wider genetic mix from which the rest of us derive our ancestry.

  The Long Walk to Australia

  Most of the evidence now suggests that a small number of people, perhaps a single band, crossed over from Africa to the Arabian peninsula near what is now Yemen about 65–70,000 years ago. All non-Africans, despite their superficial differences, are said to be descendants of this tiny tribe.7 We do not know why they left Africa but major droughts may have played a role as studies suggest that the water in Lake Malawi dropped by 95 per cent.8 The landscape these humans were traversing would have looked very different from what we see now. The planet was a lot cooler, sea levels were far lower and shorelines extended 50–100 kms further out from today’s contours. Thus, the hop over from what is now Djibouti to Yemen, across the Bab-el-Mandeb, would probably have been a short journey. Unless they crossed during the brief periods that the strait was dry land, it does suggest that early Homo sapiens already had the capability to build some sort of raft.

  The Yemen–Oman coast encountered by the migrants would have been somewhat wetter than it is now and the Indian Ocean monsoons probably watered this area. Even today, a small area of Oman gets monsoon rains. As our ancestors moved further north, they would have arrived at what is now the Persian Gulf. However, at that time the whole area was above water forming a well-watered plain. As pointed out by researchers like Jeffrey Rose, the Persian Gulf ‘was once a low-lying floodplain beginning at the confluence of the Tigris and Euphrates Rivers in Mesopotamia, the Karun River draining off the Iranian Plateau, and the Wadi Batin River flowing across northern Arabia. Together, these systems joined together into the Ur-Schatt River Valley. Further downstream, the Ur-Schatt was fed by additional surface runoff from both eastern Arabia as well as the Zagros Mountains. The Ur-Schatt catchment zone terminates at a large lake basin (>100,000 km2) positioned in the heart of the Gulf some 140 m below current sea level.’9

  In other words, the ‘Gulf Oasis’ was a veritable Garden of Eden and there was probably a significant expansion in population. Soon, they began to spread out along the Makran coast into India.10 Today, the dry, sparsely populated deserts of Baluchistan look like a barrier between the worlds of the Indian subcontinent and the Middle East, but 60,000 years ago the coast was much wetter and acted as an important grassland/scrubland corridor for early human migrations. The coastline was also much further out and what is now the Saurashtra peninsula of Gujarat was not a peninsula at all but a continuous coast. Thu
s, the stretch from the Persian Gulf to north-west India was a genetic and cultural continuum for most of prehistory.

  There is an interesting twist in the human story at this stage. As already pointed out, there were other human species around when Homo sapiens made their way out of Africa. They would all go extinct over time—the Neanderthals, for instance, steadily withdrew into Western Europe till the last of them died out in Gibraltar about 24,000 years ago.11 We do not know exactly why they died out. Changes in climate may have played a role but it is difficult to avoid the conclusion that the arrival of Homo sapiens was an important factor. Perhaps the Neanderthals lost their best hunting grounds to the new entrants or perhaps our ancestors brought deadly diseases with them from Africa. Nonetheless, scholars have often speculated that there may have been some interbreeding between Homo sapiens and other humans.

  Svante Pääbo and his team at the Max Plank Institute, Liepzig, finally cracked the puzzle when they discovered that around 1–4 per cent of the DNA of all non-Africans is derived from Neanderthals. This interbreeding, moreover, appears to have happened soon after Homo sapiens arrived in the Middle East. Most of the offspring from such mating were probably infertile, like mules derived from the mating of horses and donkeys, but a small number were able to pass on their genes. This means that the Neanderthals did not entirely die out but live on within us. Of course, this finding merely confirms what has long been suspected by anyone who has attempted to drive on the roads of Delhi.

  The journey of how Svante Pääbo made this discovery is itself a story worth reading. Interested readers should pick up a copy of his autobiographical book, Neanderthal Man: In Search of Lost Genomes, published by Basic Books in 2014.

  A research paper published in 2014 further reveals that the Neanderthal DNA that survived relates mostly to hair and skin.12 Although we do not yet know what this implies, it should be noted that Neanderthals lived in a cold climate and were light-skinned and may also have had light hair. In contrast, early Homo sapiens would have all been uniformly dark given their tropical origins. One possibility is that Neanderthals introduced a variation in skin tone that would later get exacerbated by natural selection as modern humans settled in different climate zones due to factors like vitamin D deficiency, melanin protection from sun and so on.

  About 50–55,000 years ago, a small adventurous group seems to have left the Persian Gulf–India continuum and headed east. They probably made their way along the Indian coast on foot and kept going till they reached what is now South East Asia. Almost the whole tribe seems to have kept moving since they have left only the tiniest genetic traces of their passage through the Indian subcontinent. When the group arrived in South East Asia, the sea level was much lower than it is today, and many of the islands of the region would have been connected by land to the Asian mainland. Thus, the group would have been able to spread out quickly on foot. Their descendants are the Melanesians who now live in Papua New Guinea, Fiji, and parts of eastern Indonesia.

  The early Melanesians were initially traversing territories that were already inhabited by other human species. There is evidence that they interbred with at least one such group, the Denisovans. Genetic studies show that Denisovans contributed up to 6 per cent of the DNA of Melanesians. Given all this mixing, forget racial purity, it seems most of us are not even pure Homo sapiens!

  Then, about 45,000 years ago, a branch of this Melanesian group hopped across to Australia. Even allowing for lower sea levels and extended coastlines, this would have required the ability to cross a significant body of water. We know this because the flora and fauna of Asia and Australia have remained separate despite being so close to each other. An imaginary line called the Wallace Line, that runs between the Indonesian islands of Bali and Lombok, separates the two ecosystems. Although the two islands are barely 35 kms apart, the channel between them seems to be deep enough for animals from mainland Asia (such as the tiger) to make it to Bali but not Lombok even when sea levels were at their lowest.

  The ancestors of the Australian aborigines, therefore, must have acquired the ability to build rafts that could cross seas that other human species could not. The arrival of humans in Australia was a major event. So far, Homo sapiens had been traversing lands that had witnessed other hominid species but they were now entering virgin territory. Their entry into Australia had a dramatic impact on the flora and fauna of the continent.

  As an island that had been long separated from other continents, Australia was home to plants and animals that had evolved in isolation for a long time. There was a 200-kg, 2-metre-tall kangaroo, a marsupial lion, giant koalas and flightless birds twice the size of an ostrich. The diprotodon, a giant wombat weighing 2-and-a-half tons roamed the forests.13 Many of these mega-creatures were marsupials who gave birth to small, helpless offspring that they then nursed in an abdominal pouch. Even the smaller creatures were strange, such as the platypus which is an egg-laying mammal with webbed feet and a duck’s bill.

  Human entry into this ecosystem had a devastating effect. Within a few thousand years almost all of the mega-fauna vanished. Of twenty-four species weighing over 50 kgs, twenty-three became extinct. It is thought unlikely that natural cycles like climate change would have caused this mass extinction since these creatures had already survived several cycles. Hunting for food was probably only one of the ways in which humans caused extinction. The ancestors of the Australian aborigines probably upset the overall ecological balance in several other ways. For instance, they may have used fire to clear and manage their landscape in order to benefit some species at the expense of others (contrary to popular perception, many hunter–gatherers actively managed their territories). The eucalyptus, which is rare in fossil records till 45,000 years ago, suddenly became very common at the expense of other plant species. In turn, this would have upset the whole food chain. This fits a pattern that we witness repeatedly through history whenever humans entered a virgin ecosystem like Madagascar or New Zealand.

  We know virtually nothing about the individuals who made up these groups of early human explorers—their names, their world view, their relationships with each other. However, they have left behind paintings and handprints in a cave in Sulawesi, Indonesia. Discovered in the 1950s, they were originally thought to be 10,000 years old but have recently been dated to almost 40,000 years ago, among the oldest in the world.14 The handprints, which include those of both adults and children, are particularly intriguing as if they are reaching out to us through the mists of time. They were created by spitting out a mouthful of mineral ochre over an outstretched hand in order to leave a stencilled outline. The result is very similar to the handprints made on rock surfaces by Australian aborigines well into modern times.

  Populating the Indian Ocean Rim

  As narrated above, a small group of modern humans made it out of Africa about 65,000 years ago and around 45,000 years ago they reached Australia, on the other side of the Indian Ocean. A substantial population remained in the Persian Gulf–north India continuum and one by one other groups migrated out.

  Some 40,000 years ago, another group made its way across India to South East Asia. We cannot be sure but 42,000-year-old stone tools found recently in Purulia, in the Indian state of West Bengal, may be the remains of this migration.15 When these people finally arrived in South East Asia, they would have found a terrain quite different from what we see today. As already mentioned, the sea level was a lot lower and the coastlines much further out. Islands like Sumatra, Java and Borneo were joined to the Asian mainland as part of a land mass called Sundaland. The new group, however, seems to have taken a more northward route than the Melanesians and settled in what is now Laos, Thailand, Vietnam, parts of southern China and probably extended out to adjoining areas that are now under water.

  A recent study by a consortium of geneticists argues that this group of hunter–gatherers, usually associated with Y-chromosome haplogroup O-M175, became the ancestors of most people who today live in East and Sout
h East Asia including the Chinese, Japanese, Vietnamese, Thai, Tibetan, Burmese, Malay, Filipino and most Indonesians.16 The Polynesians scattered across the Pacific are also derived from this group, as are a number of tribes who live in eastern India. At this stage, however, we are still dealing with small bands of closely related people. We will later see how subgroups descended from this migration would colonize the eastern Indian Ocean rim and even make their way to Madagascar.

  Meanwhile, new groups continued to be pumped out by the Persian Gulf–north India area. Some headed into Europe, some decided to brave the freezing Siberian cold and a few even headed back to Africa. One specific group headed out around 30–35,000 years ago and settled in southern India. Not only was the coastline further out but Sri Lanka was then attached to India and there was a large area of dry land off the coast of present-day Tamil Nadu. In fact, as the planet drifted into a new Ice Age, the new migrants would have witnessed a further expansion of land area as sea levels kept falling. This group would evolve into what geneticists call ‘Ancestral South Indians’, which is one of the two main founder populations from which most Indians derive their ancestry.17 Another group would make its way to the Andaman and Nicobar Islands (the ancestors of the Onge).

  One should not be under the impression that the population ranging from the Middle East to north-western India was static except for the occasional outward migration. This population too was undergoing constant mutations and churn. Just as an illustration, take the male lineage known by geneticists as R1. This lineage emerged somewhere in the Persian Gulf–north India continuum, possibly Iran, before the last Ice Age. At some point, around 25,000 years ago, it gave rise to a western branch, R1b, and an eastern branch, R1a.18 The former would eventually find its way to Western Europe where R1b is today the most common lineage. In contrast, R1a (particularly a subgroup, R1a1a) would later become an important component of the genetic cocktail that scientists call the ‘Ancestral North Indians’ who are the second of the two major founder populations from whom most Indians have descended.