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What Draws Humans to the Oceans?
29 Jul 2011
by Lee Rimmer
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 SpaceAround 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.
Lobe-Finned FishOur 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.
Water BabyThe 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.
Homo Erectus"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.."
ok..ive been doing research with my wonderful extended Little family... we are on the ground floor of putting this wonderful Mermaid Tale(tail)