“We are tied to the ocean. And when we go back to the sea, whether it is to sail or to watch – we are going back from whence we came.”
John F. Kennedy
There are 326 million cubic miles of water on our 4.5 billion year old planet Earth, with the oceans holding 97% of it. Where Earth’s water came from is still unknown to scientists, but water-rich comets, asteroids and meteorites, or even chemical reactions within the Earth’s own rocks, are the likeliest sources. Wherever it came from, it was a relatively swift process in Earth’s history because the oceans had achieved their present volumes by about 3.8 billion years ago.
Pacific Ocean from Space
Around 400 million years ago, lobe-finned fish used their limb-like fins to pull themselves out of the shallow water of the Earth’s coastlines and up onto the shores, breathing air through newly evolved lungs. They were the common ancestor of much of the land-dwelling life now in existence – including human beings.
Our attraction to the sea has not necessarily been constant throughout our evolution. When primates evolved 55–58 million years ago, they were tree-dwelling animals. Most species today live in tropical rain forests and will spend most of their lives in trees. Some live outside of the tropics, often at altitude in mountainous terrain. A few species of monkey can swim and are comfortable in swamps and watery areas, but generally most primates are shy of water.
So what makes humans alone among the great apes in exploiting the sea?
The Aquatic Ape Hypothesis proposes that the common ancestors of modern humans, sometime between 6 and 2 million years ago, adapted to a life of wading, swimming and feeding on the shores of lakes, rivers and seas. The hypothesis focussed on our differences with other great apes and our similarities with some aquatic mammals. Proponents of the hypothesis point to our hairlessness compared to other apes, our subcutaneous fat for insulation, our hooded nose designed to keep out water, our ability to control our breathing to allow diving and swimming, our possession of the mammalian diving reflex in cold water, and vestigial webbing between our fingers.
Beluga Whale and Aquatic Ape?
While Modern Humans, the Neanderthals and earlier species of the genus Homo were better suited to aquatic environments than other apes, the Aquatic Ape Hypothesis has been rejected by most scientists in the face of more likely explanations within conventional theories of human evolution. In fact, most aquatic mammals have thick fur and swim very well; hairless skin is only an advantage for fully-aquatic mammals such as whales and dolphins that dive, swim quickly or migrate long distances. It is more likely that we lost our body hair to lower parasite load and that our breathing control developed through our use of speech. The mammalian diving reflex is exhibited by terrestrial mammals as well as aquatic ones, while our subcutaneous fat distribution is nearly identical to that of other primates and allows for improved regulation of body temperature. The shape of the human nose is believed to be related to climatic adaptations rather than to prevent water entry while swimming.
Basically, although we like to think we are, we are not very good swimmers. Our bodies are not well suited to quickly propelling ourselves through water. Swimming is essentially a learned skill. Newborn babies do have an affinity with water, having spent months in the womb suspended in fluid. They will instinctively move their arms and legs under water and the mammalian diving reflex will make them hold their breath as a survival instinct. But, ultimately, they can’t lift and hold their head above water to breathe until they are at least 6 months old.
The First Mariners
Coastal areas were probably of little use to primates and the earliest species of Homo. They didn’t know how to use the sea as a food source, so for millions of years they only ate land plants and animals. Then, something changed. Seafood began to play an important role in human development.
A study published in the Proceedings of the National Academy of Science revealed that, almost 2 million years ago, hominids in Kenya began eating food such as crocodiles, turtles and fish. This may have been the catalyst for the evolution of smaller-brained hominid species into larger-brained Homo species – in particular, Homo Erectus, the first hominid to explore the world outside of Africa.
As well as exploiting the sea for food, Homo Erectus may well have used coastlines to move long distances. Furthermore, Homo Erectus actually took to the sea, perhaps as long ago as 1 million years. This is a proposed date for the first occupation of Atapuerca, in northern Spain, where human remains and stone tools were found and the likely result of a 12 mile journey sea journey by ancient hominids across the Straits of Gibraltar from Morocco. Whether this voyage was ‘deliberate’ or not is up for debate – skeptics suggest that it was made accidentally, perhaps the result of being blown out to sea by storms on a raft built for hugging the coastline. It is more likely that the motivation was new territory, new seafood resources or just curiosity, because it didn’t happen just the once. Homo Erectus also undertook the 15-mile voyage from the Indonesian island of Bali to nearby Flores, where excavations have revealed 700,000 to 800,000-year-old stone tools.
Homo Heidelbergensis, probably the direct ancestor species of both Neanderthals and modern humans, effectively colonised the island of Crete over 130,000 years ago in a number of expeditions by sea. The National Geographic reported how archaeologists found more than 30 hand axes and several hundred stone tools, resembling those used by hominids in Africa and mainland Europe until about 175,000 years ago, in nine different locations over the southwestern coast of Crete.
Crete has been surrounded by sea for around 5 million years. The world was in its last ice age at this point, resulting in much lower sea levels. Even when the Mediterranean was at its lowest known point, 440 feet below current sea level, a journey from Turkey or Greece would have involved 3 separate water crossings ranging from 12 to 24 miles each to reach Crete. A sea journey from Africa would have been over 125 miles of open water. The finding of several hundred stone tools in nine different locations suggests a number of people large enough to sustain a population and that they didn’t just accidently drift over the once – they had mastered sea travel.
Homo Heidelbergensis Settlements on Crete
image source – Archaeology.org
Survival on the Coast
Any archaeological evidence of modern humans in Africa earlier than 100,000 years ago is very rare. It is thought that the total population of modern humans never peaked at more than 10,000 at best and shrank as low as 1,000 at worst, so most evidence of very small populations concentrated in coastal areas would have long since disappeared beneath the sea. In 2007, however, it was reported that anthropologist Curtis Marean had found evidence of early modern humans living on the coast of South Africa 164,000 years ago, harvesting food from the sea. They probably had to expand their diet to include seafood for survival in the face of harsh environmental conditions – with most of the planet’s fresh water locked into massive ice sheets, swathes of the African homeland had turned into desert making food difficult to find. We weren’t the only species to seek refuge on the coast in this way. Although we did teeter on the edge of extinction on a number of occasions it was the Neanderthals who did finally succumb. The archaeological evidence suggests the very last of their number lived around a cave system on the remote south-facing coast of Gibraltar, then surrounded by a coastal plain, between 24 and 28,000 years ago.
(top) Gibraltar today with caves at its base; (bottom) reconstruction of late Neanderthal times with lower sea levels © Gibraltar Museum
Ancient Seafaring by Modern Humans
When modern humans did finally follow their ancestor species and migrate from Africa to populate the rest of the world from around 60,000 years ago, genetics has shown how they unlocked new territory by crossing seas and oceans.
Initially, the first small group living in East Africa migrated north east and crossed the Red Sea into the Arabian peninsula. Today the Red Sea is about 12 miles wide at it’s narrowest point but at that time it was much narrower and the early explorers would have island-hopped on simple rafts. To get to Australia from the Asian mainland around 50,000 years ago, they had to cross a 600-mile-long band of islands and at least 10 ocean straits – the largest spanning 44 miles of open water – probably using simple bamboo rafts. The Aborigines of Australia are the descendants of a subset of the first wave of migration out of Africa.
Other settlers continued eastwards to China and eventually reached Japan by about 35,000 years ago, leaving a trail of coastal settlements which has left its mark in the subclades of Y-chromosome haplogroup C prevalent throughout Southeast Asia. The colonisation of the frozen climes of Europe began around 45,000 years ago by settlers travelling northwest overland from the Middle East. As modern humans mainly with Y-chromosome haplogroup I, they co-existed with the Neanderthals already settled there – perhaps for as long as 15,000 years – before the Neanderthals final displacement and extinction.
The dates and routes travelled in populating the American Continent have long been hotly debated. The traditional theory is that the earliest settlers from Central Asia moved between eastern Siberia and Alaska across the Beringia land bridge around 40,000 – 17,000 years ago, along ice-free corridors when sea levels were lower. Another route may have taken them down the Pacific Northwest coast to South America as far as Chile, either on foot or hugging the coastline in primitive boats.
The most intriguing proposal, the Solutrean Hypothesis, suggests that a small number of settlers migrated from Ice Age Europe to North America across the Atlantic Ocean. Anthropologist Dennis Stanford says that he can directly link the migration through similarities between European stone tool technology associated with the Solutrean culture, dominant in France and Spain 17 – 21,000 years ago, and later Clovis technology found throughout North America. How could such an early Atlantic crossing be possible? The hypothesis was investigated by the BBC’s science show Horizon – Stone Age Columbus – and showed how Europeans could have crossed the North Atlantic along the edge of the pack ice that extended from the Atlantic coast of France to North America during the last glacial maximum. Using Inuit-style survival skills, these people could have crossed in small watercraft using ice floes as stepping stones. The ice could have provided an overnight base, a source of fresh water, a source of food from seals and fish, and a source of heating fuel from seal blubber. Solutrean bone needles are very similar to those traditionally used by the modern Inuit and could have enabled the manufacture of waterproof clothing and even the construction of kayaks from animal skins.
Ice Age Atlantic Crossing?
Opponents of the Solutrean Hypothesis say that oceanographic and environmental data show that the conditions North Atlantic during the last glacial maximum could not have supported such a crossing, that there is no evidence of seafaring during the Solutrean, or that the geographical separation of the Solutrean and Clovis cultures, as well as their chronological differences, make a direct connection unlikely. Remnants of seashells and fish have been found some distance from the sea in known Solutrean settlements in Europe, but there is no evidence that they could exploit deep sea resources. A carved piece of bone depicting a mammoth found near Florida has been dated to 13,000 to 20,000 years ago and shows similarities to Solutrean art and engravings of mammoths, but has been explained as independent artistic development.
The archeology is inconclusive as most of the evidence, which would be found in Solutrean coastal settlements, is now submerged under the Atlantic. Does DNA testing provide any evidence of an Atlantic crossing?
An adaptation of Gregory L. Little’s book Mound Builders shows how the mtDNA testing of modern Native American tribes places them in 4 distinct haplogroups – A, B, C, and D. Haplogroups A, C, and D originate mainly in Siberia and confirm the route into America across the Beringia land bridge from 40,000 years ago. Haplogroup B is only found in the aboriginal groups of China, Japan, Melanesia, and Polynesia and probably came to America across the South Pacific or from Japan around 13,000 years ago. In 1997 a fifth, unexpected, mtDNA haplogroup of ancient origin – termed ‘X’ – was also identified in 3% of modern Native Americans. Haplogroup X was not of Asian origin, but found in small percentages in Europe and the Middle East – primarily in Spain, Bulgaria, Finland, Italy, and Israel. However, in 2001 the American Journal of Human Genetics reported that the ‘X’ type had been found in a tribe in extreme southern Siberia, though the ‘X’ type has since also been found in the ancient remains of the Basque people of modern Spain. Haplogroup X appeared to have first entered America in limited numbers perhaps from around 36,000 years ago, then appeared in much greater numbers from 14-12,000 years ago.
image source American Indian Artwork
A 2008 article in the American Journal of Human Genetics by researchers in Brazil maintained that haplogroup X, along with A, B, C and D, was part of the gene pool of a single Native American founding population and did not support the Solutrean hypothesis. There is enough ambiguity to make DNA evidence inconclusive and the debate will continue, but part of me hopes that such an epic undertaking – a prehistoric crossing of the Atlantic Ocean – actually happened.
The oldest physical evidence of human watercraft ever found is around 10,500 years old: a dugout canoe found in a bog in the Netherlands and an oar found at Star Carr, near Scarborough in North Yorkshire. This was not long after the end of the last ice age when Britain was still connected to mainland Europe via the landmass of Doggerland. The human inhabitants of Doggerland acquired 60% of the protein in their diets from seafood – so abundant were these marine resources, the Doggerland communities settled down into sedentary sites around its river and coastal areas. As the ice sheets melted, the Doggerland people will have seen ever increasing amounts of their land being swallowed up by the North Sea; but the end of Doggerland was probably swift and violent. The Storegga Slide around 8,200 years ago saw a substantial piece of the Norwegian continental shelf slide into the Norwegian Sea. The resulting 66 ft high tsunami wave that swept through the North Sea would have had a devastating effect on Doggerland’s coastal communities. Following the Storegga Slide, the remainder of Doggerland sank beneath the waves and Britain finally became separated from the continent. All that remains of Doggerland today is Dogger Bank, a large sandbank in a shallow area of the North Sea; it is a productive fishing area, as well as a rich source of artefacts.
Doggerland 10,000 years ago Dogger Bank today
It has been suggested that the submergence of Doggerland was retained in folk memory and embellished to become the fabled Atlantis; so have many locations around the coastal areas of Europe, such is the occasionally destructive power of the sea. Water will have always played an important part in mythology from the earliest societies. As folktale expert Steve Gregory notes, to them, the oceans and seas were a vast source of both life and terror, stretching to infinity for all they knew. On land, man’s natural enemies could be seen, hunted, killed, skinned and eaten. But out at sea lurked strange creatures of unfathomable size and deadly intent. Huge rogue waves could come seemingly from nowhere to capsize small vessels, as could whirlpools which would suck both them and their crews to the bottom. Unsurprisingly, each society created a panoply of gods lurking in the oceans’ depths, to explain their creation and to appease their force.
There is something about the sea which has attracted, even mesmerised, the human brain for at least a million years. That brain power, which drove us to overcome our fear of it and construct floating craft to take to its open waters, is what differentiates us from other primates – whether in search of new resources, to flee a threat, or to seek out that mythical great civilization which must have always been somewhere across the ocean. Out of nearly 7 billion human beings on the planet today, around 60% live along the world’s estuaries and coasts – sometimes at great risk. We are not designed to live in the sea and we can probably never hope to control it, but we have learned to exploit it for our survival – and to enjoy it. That’s why we still pay over the odds to live next to it and wax lyrical about holidaying on it.